Datasheet CTC 177 Datasheet

Page 1

CTC177

Circuit Chassis Part Problem SolutionModel

Audio

CTC177 R1904 Set had low audio output which would vary with

the volume. Found pins 2 and 4 of u1901 at .65 volts dc, due to r1904, and r1906 increasing in value. Found resistors to both be approx. 2kohm, should be 150 ohm.

CTC177CD L2304 Low volume and distorted sound. Measuring

CTC177 CF1201 Audio noisy. When connecting an audio source to thFound 0 volts at U1001 pin 58. Found pins 2 and

CTC177BH2 U1001 Intermittent crackling in the left channel . U1901

F31671

voltages we found u1001 pin 2 (if vcc) was 5.2 volts.

F276325E

had been replaced .Found that pin 60 of u1001 was at .6 dc supposed to be around 3.81vdc. Resistance measurement from ground the l channel was 60 ohms. Lifting the pin didn't increase the resistance.

Replaced r1904 and r1906, which restored full volume.

Replaced l2304 (u1001-2) which measured 360 ohms.

Disconnecting the foil on the pad of pin 60 to r1901 and hardwiring between pin 60 and r1901 resolved the problem.

Audio

CTC177BB CF1201 Noisy sound, connecting a sound source to the

F27150SE

audio input jack the sound was ok. Found 0 volts at u1001-58.

Clipped leads of cf1201, pins 2 & 3 were touching and grounding u1001-58.

Page 2

Circuit Chassis Part Problem SolutionModel

Audio

CTC177AC CF1201 Noise in audio on cable channels with graphics,

CTC177 CF1201 Audio noisy on cable channels with graphics. Video Found CF1201 pin 3 had a bad solder connection.

CTC177BB ground Slight buzz in audio when graphics or osd is being

CTC177 C1953 Audio missing Found C1953 was open. Replacing C1953 repaired

F25190SE

video had audio beat on the same channels. He had repaired grounds for a vertical problem. Checked the tuner, it checked normal. After a lot of clarification of the symptoms I told him to replace cf1201 the

F27150SE

displayed. The buzz was also present in the mute condition.

Removing cf1201 & reinstalling properly cleared up sound & pic.

Resoldering the recommended ground connections cured the problem.

the

Audio

CTC177 OPEN TRA Audio missing U1701 had no signal input at pin 5. Voltage at pin

CTC177 U1901, R1 Audio missing The audio output, U1901, was blown. The

replacemen

Page 3

Circuit Chassis Part Problem SolutionModel

Audio

CTC177 TRACE Audio int and Audio noisy on the left channel only Found a broken printed trace going to JW413.

The t

CTC177 U1001 Audio crackle in the left channel only. Replacing Pin 60 of U1001 measured 0.6VDC, it should be

arou

CTC177AF2 Trace No audio, u1701 had no signal input at pin 5.

Voltage at the pin was at 0 volts. Lifted the pin and voltage returned to the pin. Traced signal from u1001 pin 3 to c1703. Had signal to one side but not the other. Measured resistance on the trace to ground

CTC177 C1201 Audio distorted intermittently. U1001 pin 57 was at 4.7V instead of 5.9V. C1201

Jumped trace from c1703 to pin 5 of u170125GT520

Audio

CTC177 JW107 Problem with interface between MCR029 and

external

CTC177 JW431 Set had intermitten audio. The audio mute transist Cleaned up the board between the two jumbers fix tCHASSIS:

Remove jw107 from board restored operation of mcr

Page 4

Circuit Chassis Part Problem SolutionModel

Audio

ctc177 c1201 Intermittent distorted audio. U1001 pin57 was at

4.7v instead of 5.9v. Found c1201 off of pin 57 installed backwards. Installing new part with correct polari ty restored operation.

CTC177 C1909, R19 The unit would not go into Audio mute when

selecte

CTC177 trace Intermittent and noisy sound on left channel only. Repaired broken printed trace to jw413. Trace was

ctc177 u1901 Audio output, u1901, blown. Replacement gets

27GT617

real hot. After a minute or so the dc voltage on pin 9 of u1901 starts to pulsate down to 3 volts from 26 volts. Pin 10 also pulsated, but pin 8 stayed at zero. Found that one end of r1903 was touching the hea

Install new part with correct polarity.G27683hp

There was virtually no DC logic change at U3101 pi

broken on r1901 side of jumper wire.

Repositioned r1903.

Audio

B+ Regulator

CTC177 R1903, R19 Audio low Pins 2 and 4 of U1901 were at 0.65VDC. R1904

and R

CTC177 CR4109 Poor Regulation. Picture width would decrease

when

Regulated B+ would vary from 140VDC to as low as 1

Page 5

Circuit Chassis Part Problem SolutionModel

B+ Regulator

CTC177 C4124 Tic tic. The set makes a ticking noise after the p Pin 3 of IHVT was cycling between 100V and

125V. W

CTC177 R4105 The set makes a Buzzing sound in the off mode. The regulated B+ was high. The set operated

normal

CTC177 R4136, C41 Arcing C4107 vents and the regulated B+ was 400VDC.

C4107

CTC177 C4007 Standby voltages high. The 140 volt measured 180 volts. The raw B+ had

Cabinet

Chroma

CTC177 IR WINDO Remote operates only at very close ranges. Removing the IR window allowed the remote to

opera

CTC177 R2806 No chroma. The waveform on pin 48 of ic1001

was close to 1 v peak to peak for the luminance signal but on pin 49 there was not any waveform for the chroma. There was chroma on both sides of c2805 but it was only on one side of r2806 on the foil. Resolderi

Resolder r2806

Page 6

Circuit Chassis Part Problem SolutionModel

Chroma

ctc177 c2806 No color. Applying 4 volts to pin 47 of u1001 to

defeat the color killer brings back good color. Had replaced u1001 and y2801. The dc voltage on pin 47 was slightly low, 3.3 volts. Found that lifting c2806 (off of pin47) allowed the dc to rise to

3.75 vo

CTC177 N\A No color on channel 3 only. Reverse instructions on sps 4313 packed with

CTC177AF3 R2801 Set had no color and in troubleshooting found pin

CTC177 C2801 Intermittent color. pin 47, u1001 measured 2.2v.

G27683HP

47 of u1001 to be 3.3 volts due to one side of r2801 not soldered.

it should have measured 3.6v. found a leaky capacitor (c2801) off of pin 47, u1001.

Replaced leaky c2806.25GT522

211962. Change r2805 to a 750 ohm (215200) at coordinates 16b & c2801 to 1uf (189991) at 12ee. Replace r2806 at 16b with a chip jumper (205408).

Soldered r2801

Replacement of c2801.

Chroma

CTC177BE U1001 No color, no station audio (noise only). Would

direct access channels, but tuning was slow. Autoprogram wouldn't capture anything due to slow tuning. Checking around y2801, we found that u1001-15 measured 9 ohms to ground. Replacement of u1001 restored no

CTC177 R2806 Chroma missing. The waveform on pin 48 of IC1001 was close to

Replace u1001.F27631SF

1Vp-

Page 7

Circuit Chassis Part Problem SolutionModel

Chroma

CTC177 R2801 Color missing. Pin 47 of U1001 measured 3.3V. There was a bad

sol

CTC177 C2806 Color missing Applying 4 volts to pin 47 of U1001 to defeat

the

CTC177 C2805 Color missing. Video was normal but was in black a There was video out at pin 51 of IC1001, but no

CTC177 C2805 No color video okay in black and white. Had

video out 51 but no color back in pin 49 of ic1001. Ic1001 and the 3.58 crystal had both been replaced before the servicer call tech. line. Found color on one side of c2805 but none on other side.

Resolder cap. and color was restored. C2805 is the path for color to pin 49.

High Voltage

CTC177 R5014/16 Red picture. Low drive from q5002 and q5003.

Servi

CTC177 C7410 High Voltage @ 10KV; 26V, 12V, -12V Run

sources OK

Replacement of resistors R5014/16 restored picture

Replaced c4710.

Page 8

Circuit Chassis Part Problem SolutionModel

High Voltage

Horizontal

CTC177 R4904 Dead set There was 2.5V on pin 26 of U1001. U1001 had

been

CTC177 R4119 Vertical int The 7.6V run source was varying at pin 32 of

U1001

CTC177 TRACE 14 Video missing/OSD missing. Audio was normal. Normal video was present at U1001-44. checked

U100

CTC177 T4301 Dead. hot had shorted and f4001 had opened

.found connections at primary of the horizontal driver transformer t4301 bad.

Resolder connections at the horizontal driver transformer t4301.

Horizontal

CTC177 C4403 Insufficient horizontal sweep.horizontal near

collapse. Tracing waveforms at the yoke return capacitor the signal dropped off dramatically on one side of the capacitor.

CTC177 CR4402 Pincushion error evident. Servicer found shorted

q4851 pin out put transistor. Upon replacement the new part promptly went up in a puff of smoke. Pulling the collector loose on the pin output, the dc level on the foil was at 39vdc with horizontal ac also

Replaced open c4403.

This applied reg b+ to the pin circuit thereby toast ng q4851. Replacement of the above components restored normal operation

Page 9

Circuit Chassis Part Problem SolutionModel

Horizontal

ctc177 short Dead data and clock line from u3101 were not

present, which is correct and they would start up when the power button is hit. There is no dc voltage on pin 24 of u1001 the trace from r4311 to jc404 was reading 0 ohms to grnd.. Found trace under r4308 was

CTC177 R2709 Bright screen no video pin 31 of u1001 was 7.4

ctc177 r4904 Dead. Found 2.5v on pin 26 of u1001. U1001

CTC177 C4403 Dead set with c4105 failure. replacement of

25GT506

volts instead of 6.36.

had been replaced. Found r4904 open. Pin 26 pulled up from inside u1001.

c4105, chassis will run for a very short time with c4105 failing again. replacement of c4403 (yoke return cap) resolved the problem.

Removed short.

Found resistor r2709 (27k) was open. Resistor is off pin 4 of flyback.

Replaced r4904 and set worked.f25651

Replacement of c4403.

Horizontal

CTC177 CR4303 Found the horizontal pulse at q4301 to be 5.7vpp

and -2.3vdc at the base, and .4vpp and 145vdc at the collector. Cr 4303 checked open.

CTC177AA3 TRACE Dead set. Pin 24 of u1001 was at 1.5 volts in

standby it should of been 6 volts. There was leakage in the trace at the two jumpers jc404 and jw317 off pin 24 of u1001.

Replaced cr4303, restored operation.

The two jumpers were removed and a wire jumper was placed between resistors r4311 and r4310.

Page 10

Circuit Chassis Part Problem SolutionModel

Horizontal

CTC177AG leakage Turning tv on, it came up than down. Grounding

ctc177 trace Dead. U3101 pins 15 and 16 ok. U1001 pin 26

CTC177 CR4403 Pincushion problem.repeat failure of q4851 in the

CTC177 T4301 Dead set. T4301 had an open primary winding.

F25651

pin 26 of u1001 tv stayed on with correct high voltage. Checking voltage on q4901-b found 7.5 volts. Also, found 700 ohms across xrp test points.

25gt506

(xray shut protect) at 2.6v.

F27631SF

pincushion circuit.the voltage at the collector of q4851 was down to about 12 volts .it should be about 17 volts.cr4403 was checked out of circuit(it checked good).the diode was breaking down under load.

Set w

Tech removed printed wire between r4902 & xrp1 and replaced with a jumper. Leakage in circuit board.

Found and repaired an open trace between pin 26 and r4904. Set then worked normal.

Replacement of cr4403 as well as the damaged q4851.

Replacement of T4301 repaired the setCHASSIS:

Horizontal

CTC177 connection Picture pulled in 1 to 1.5 inches on both sides.

Found pin 2 of l4853 not soldered. This connection was on the coil not the board.

ctc177 c4407 Picture is too tall and bowed out at the top. The

sides are bowed in.. The collector voltage on q4851 is at 19vdc.. The vertical height can be controlled by the service menu...

Resoldered l4853.G27683

Replaced def c4407.. Cap checked good out of ckt

Page 11

Circuit Chassis Part Problem SolutionModel

Horizontal

CTC177 C4303 Narrow pix. Horizontal waveform at collector

showe

ctc177 t4401 Dead. Set was intermitant initially. 140v was at

148. Checking voltages we found a poor solder connection on pin 1 of the fly.

CTC177 trace No video or osd- audio normal had changed

u1001. Found normal video at u1001-44. Checked u1001-25 for 8vpp horiz. Pulse and found no pulse with 6vdc (should be 2.1vdc). Found a normal 25vpp pulse at t4401-8, but not at r4303. The trace between t4401-8 an

CTC177 CR4402 Hot failure.found cr4402 leaky. have seen a few

of these diodes failing.

Remove solder splash c4303 (emitter q4302).

Repair of solder connection fixed set.f27631sf

Repair trace27GT613

Replaced q4401. cr4402.

Horizontal

CTC177AM2 Originally the set had a blown horizontal output

transistor. After replacement the sides pulled in and pincushion correction was not correct. The servicer had replaced c4402, c4406 and the yoke return caps without any improvement. This set has a 27 inch t

ctc177aa3 Q4301 Turn set on would have drive out of u1001-24 to

base of q4301 no collector wave form and had 17v on collector. Tech may have caused this,set came in for ground problem and the set would not turn on after he soldered the set.

When the servicer reinstalled the chassis back into the original set the width and pincushion problem disappeared.

Replace q4301x25103sg

Page 12

Circuit Chassis Part Problem SolutionModel

Horizontal

CTC177 C4403.HO Intermittent failure of the hot. found an open

(under load) r4403 and a intermittent c4403. the set had worked briefly with the first hot replacement.

CTC177 T4301 Dead set. Tracing the horizontal drive signal revealed there

CTC177 C4407 Picture would bloom with channel changes or a

change of screen voltage. Width was also affected.

CTC177AR2 R2709 Intermittent vertical black bar in center of

picture. Found r2709 overheated.

Replacement of q4401, r4403, c4403.

Replacement of c4407 which is located across the pincushion damper resolved the problem.

Replaced overheated r2709 (ihvt pin 4).F25215W

Horizontal

CTC177BE C4313 No video or osd, replaced u1001, 3201 and 3101.

Pin 25 of u1001 had 4.3 volts with a waveform of only 2.1 volts peak to peak.The servicer noticed c4313 in parallel. Lifting the cap returned video and osd. Checking the service lit and c4313 is not shown. T

CTC177AA R4201 Intermittent xrp shutdown . By grounding pin 26

25GT506

of u1001 the set would operate. The base voltage on q4901 would vary lower causing the xrp to trip. The base of q4901 read 13k to ground. Removing r4201 off from it's pad and cutting along the foils with a k

Replace c4313.F27630

Removing r4201, cleaning the traces underneath this resistor and reinstalling this component took care of the problem.

Page 13

Circuit Chassis Part Problem SolutionModel

Horizontal

ctc177bg q4851 Picture is too wide. Horizontal freq. Was set ok.

Read a short across cr4403 in circuit.

ctc177 c4402 Cycles when turned on. Found by substitution

c4402 bad.

CTC177 PCB Dead set.chassis tries to power up.found the 140

volt supply missing at the collectors of both the horiz. Driver and output.found an open trace at pin 2 of the ihvt.

CTC177 T4301 No high voltage had drive to horz driver transistor Horz driver transformer t4301 had a broken wire

27GT613

Found q4851 shorted c-eg27341wk

C4402.x25101

Repaired open trace.

at terminal # 3 was able to repair.

Horizontal

CTC177 C4706 Dead set servicer had replaced cr4704 and r4702

the run voltage came up to 4 vdc. Tried another diode but the voltage remained low. Re- moved one end of c4706 and restored the 12vdc.

ctc177 trace Dead set. Clock and data on u3201 pins 5 and 6

are ok. Found drive for horizontal coming out of u1001 pin 24. Found open trace between l4401 and pin 6 of t4301.

Replaced c470625GT542

Jumped trace with wire fixed set.

Page 14

Circuit Chassis Part Problem SolutionModel

Horizontal

CTC177AF2 C4307 Set had zig zag lines in the top 4" of the picture.

Checking waveforms on the set showed what was described as a ringing in video and horiz drives. Subbing in a horiz drive at pin 24 of u1001 cleared up the picture. Checked voltage at pin 23 and it at .5

CTC177BH2 T4301 Dead. Tracing horizontal drive signal we found

CTC177AK R4302 No video or osd no sandcastle at u1001-27, at pin

CTC177BF CR4302 Set would get a black bar on right side of pix from

27GT613

only 18v p-p on the collector of q4301.

25 the fb pulse was 7vpp but was clipped. Dc was

2.7vdc. Checking r4302 for resistance, it checked open (should be 22k). Substitution of a 22k resistor across r4302 restored video and osd.

top to bottom. Over a period of 3-5 min more bars would appear and they would get thicker. Slowly the pix would be blacked out from the right side to the left. Sandcastle pulse at pin 27 of u1001 was wr

Replace c4307.F26251ET

Replaced t4301 which checked 17 ohms across the primary (should be 37.8 ohms).

Replacement of r430225GC710

Replace leaky cr4302 clamp diode27GT617

Horizontal

ctc177 c4403 No horizontal sweep. High voltage present.

Servicer found and replaced defective c4403 and cr4401.

ctc177 adjustment Flagging at top on tuner and vcr. Readjusting the

horizontal oscillator corrected the problem. Servcier said the adjustment was a couple of numbers off.

Replaced c4403 and cr4401.j25330bl

Reset horizontal oscillator.

Page 15

Circuit Chassis Part Problem SolutionModel

Horizontal

CTC177 C4307 Flagging at the top of pix with tv video and aux

video. All voltages off pins 20,23 and 25 of u1001 checked ok.

CTC177 CR4403 Pincushion problem. Repeat failure of Q4851 in the pincushion circuit.

CTC177 TRACE Dead set Clock and data on U3201 pins 5 and 6 were

CTC177 R2709 Pix narrow Voltage checks around U1001 indicated a problem

Replacing c4307 (off pin 23 of u1001) cured the problem.

normal.

Horizontal

CTC177 C4402 Cycles on/off when turned on. C4402 was bad. Replacing C4402 repaired the set.

CTC177 T4301 Hi voltage missing. The set had drive to the horiz The horizontal driver transformer (T4301) had a

Page 16

Circuit Chassis Part Problem SolutionModel

Horizontal

CTC177 C4706 Dead set The run voltage came up to 4VDC. Removing one

end

CTC177 CR4115 Dead set All standby voltages were normal. The

microprocess

CTC177 R2709 Bright screen/Video missing Pin 31 of U1001 was at 7.4 volts instead of 6.36 v

CTC177 CR4402,C4 Dead set CR4402 was shorted. C4701 and C4505 on the 26

volt

Horizontal

CTC177 C4502 Dead set HOT leads were severed on the PCB. After

replaceme

CTC177 HEAT SYN With the antenna connected, the set would Pulse onThe heat sync that the horizontal output was

mouun

Page 17

Circuit Chassis Part Problem SolutionModel

Horizontal

CTC177 CR4402,U4 Dead set. When plugging the set in, a chirping sou A short was detected across the horizontal output

CTC177 T4401 Dead set. Initially, the set operated only intermi The 140V supply measured 148V. Checking

voltages r

CTC177 C4311 Dead set U3101 voltages were normal. Had no drive from

U100

CTC177 CBA Dead set U3101 pins 15 and 16 were normal. U1001 pin

26 (Xr

Horizontal

CTC177 CIRCUIT T No Pincushion correction. Pix narrow with sides boChecking waveforms and voltages in the

pincushion

CTC177 L4853 Pix compressed. The picture was pulled in 1 to 1.5 Pin 2 of L4853 was not soldered. This connection

Page 18

Circuit Chassis Part Problem SolutionModel

Horizontal

CTC177 CBA Dead set U3101 had normal voltages. Pin 15 had data when

CTC177 Q4302 Shutdown int after resoldering ground connections Q4302 base connection did not have any solder

on i

CTC177 Q4851 Pix narrow The collector voltage was low on Q4851. Q4851

was

CTC177 T4401 No Vertical/Audio missing. The voltage at diode CR4704 cathode was 0VDC.

Chec

Horizontal

CTC177 T4401 Dead set. The power supply made a singing noise. The collector of the horizontal output transistor

CTC177 CR4402 Dead set int Intermittently Q4851 would overheat and open.

The

Page 19

Circuit Chassis Part Problem SolutionModel

Horizontal

CTC177 CR4402, Q Pincushion error. The Q4851 pin output transistor was shorted.

Upon

CTC177 Q4401 No startup/Dead set. If the chassis was positioned Resoldering the tabs at the system control shield

CTC177 Q4401 Dead set The heat sink where the horizontal output was

moun

CTC177 CR4402 Dead set When the set was plugged in, parts on the 26V line

Horizontal

ctc177bh2 r4854 Pix on left side bowed. Cannot adjust out. U4851

4.5v on pin 2 and 3. R4854 is a 27k resistor instead of 41.2k

CTC177 C4405 Dead set. The set had a repeat failure of CR4401. Isolating

Replaced with 41.2k resistor.f27632se

Page 20

Circuit Chassis Part Problem SolutionModel

Horizontal

CTC177 R4854 Pix bowed in on left side. Could not be adjusted. Checking U4851 4.5V on pin 2 and 3 showed

R4854 re

CTC177 R2709 There was an intermittent vertical black Bar in pi R2709 (IHVT pin 4) had overheated. Replacing

R2709

CTC177 TRACE Dead set The foil at pin 2 of the flyback transformer was o

CTC177 E4403 Dead set. Pin 24 measured zero volts, it had 990 ohms to

gro

Horizontal

CTC177 CR4403 Pincushion distortion with repeat failure of Q4851 The pin damper diode CR4403 had physically

deterio

CTC177 CR4303 Dead set. The horizontal pulse at Q4301 was 5.7Vp-p and -

2.3

Page 21

Circuit Chassis Part Problem SolutionModel

Horizontal

CTC177 C4307 Flagging at the top of the picture with TV video a All voltages off pins 20, 23 and 25 of U1001 were

Ctc177 C4311 Dead set, u3101 voltages normal, no drive from

u1001 pin24 voltage on base of q4302 near 0.0. R4301 had 7.6 volts on one side, 0.0 on the other. Lifted c4311 and voltage and drive returned.

CTC177 E802 Video missing. There was no pulse at pin 25 of U1001. Pin 25 of

CTC177 c4401 TV would not turn on instantly. Followed

horizonta

Replace c4311

Replacement of c4401 and set turned on and off oka

Horizontal

CTC177 C4307 Lines in pix. The set had zig zag lines in the top Checking waveforms showed a ringing in video

and h

CTC177 R4201 Shutdown intermittently. The unit would enter

into

The base voltage on Q4901 would vary lower causing

Page 22

Circuit Chassis Part Problem SolutionModel

Horizontal

CTC177 C4313 Video missing/OSD missing. U1001, U3201 and

U3101

CTC177 Q7404 VHF channels were Snowy. Found Q7404 was shorted with 11 volts on the

CTC177 CR4302 Intermittent Jailbars. CR4302 checked good but was defective.

CTC177 CR4302 Video missing/OSD missing/Screen black. U1001 pin 25 was at 4.3VDC and pin 27 was at

Pin 25 of U1001 had 4.3V with a waveform of only 2

colle

Replacing C

2.8VD

Horizontal

CTC177 R4854 Pix bowed in on left side. U4851 measured 4.5V on pins 2 and 3. Found

resisto

CTC177 JUMPER Turning the TV on, the set comes on and then

Shutd

Grounding pin 26 of U1001 caused the TV to stay on

Page 23

Circuit Chassis Part Problem SolutionModel

Horizontal

CTC177 C4403 Horiz sweep was insufficient. The horizontal was n Tracing waveforms at the yoke return capacitor

rev

CTC177 CR4302 Black bars would appear on the right side of the p Sandcastle pulse at pin 27 of U1001 was incorrect.

CTC177 C4403, CR Horizontal sweep missing. High voltage was

present

CTC177 Q4851 Pix wide Horizontal frequency checked normal. Detected a

Found C4403 and CR4401 were defective. Replacing C

Horizontal

CTC177 TRACE Dead set There is no DC voltage on pin 24 of U1001. The

tra

CTC177 PCB Dead set. Chassis tries to power up. Found the 140 volt supply missing at the collector

Page 24

Circuit Chassis Part Problem SolutionModel

Horizontal

CTC177 T4301 Dead set HOT had shorted and F4001 had opened. Found

connec

CTC177 C4407 Pix tall and Pix bowed at the top and sides are bo The collector voltage on Q4851 was at 19VDC.

The v

CTC177 R4302 Video missing/OSD missing Had no sandcastle at U1001 pin 27. At pin 25 the

CTC177 R4301 Dead set Found voltage and output missing on pin 24 of

U100

Horizontal

CTC177 R4854 No Pincushion correction. Varying parameters P03 and P04 had no effect on

CTC177 CR4402 Dead set Found cr4402,cr4403 and q4851 shorted.G27343HP

Page 25

Circuit Chassis Part Problem SolutionModel

Horizontal

CTC177 T4401 No vertical or sound. Checking voltage at diode

cr4704 cathode we found 0vdc. Checking between pins 5 and 9 on t4401 we found an open

CTC177 T4401 Dead unit. Power supply making a singing noise.

Checking the collector of the horz output transistor to ground read shorted. Isolating the various other components off t4401 pins 1, 2, and 3 we still had a short. Flyback (t4401) shorted pin 3 to core

ctc177bh2 r4301 Dead. No volts or output on pin 24 of u1001.

Found r4301 present but not soldered in.

CTC177BH2 CR4302 Intermittent jailbars. Cr4302 checked ok but when

it was replaced it took care of the problem.

Replace t4401F31631SE

Replace t4401G25341WK

Soldered r4301.27gt613

Replaced cr430227GT613

Horizontal

CTC177 R4303 No picture with strong signal and tearing with

ctc177 CR4402 Intermittently q4851 would overheat and open.

F25651

weak signal. Less than 1v p-p at u1001-25.

G27665wk

Found the cathode lead of cr4402 was long enough so that when the chassis was slid into the tray it caught on the tray and broke the circuit trace. The break would intermittently connect and the unit would wo

Replaced open r4303 which supplies flyback pulse to u1001-25.

Repaired connection on cr4402 and the board around q4851.

Page 26

Circuit Chassis Part Problem SolutionModel

Horizontal

CTC177 Q4851 Slightly narrow pix. Collector voltage low on

q4851

ctc177 cr4402 Dead set. Replaced shorted u4101 and it blew

again immediately. Svcr found cr4402, damper diode, shorted. After replacement of cr4402, and u4101 again, it worked.

CTC177 Q4401 No-start. If the chassis was positioned vertically

CTC177 Q4401 No pix no high voltage. Traced horz signal out of

G27681CK

as for servicing the bottom side, the set would start and play normally. Resoldering the tabs at the system control shield did not help. When the horizontal output transistor leads were resoldered, the c

the collector of the horz driver transistor.

Found q4851 leaky base to emitter.27GT617

Replaced cr4402 and u4101 again.F27150se

Extending the lead through the chassis and soldering restored normal operation.

Found base lead of q4401 (horz output) broken.G27687WA

Horizontal

CTC177 CR4402 When set plugged in parts on 26v line blow up.

CTC177 Cr4402 Dead set. Upon pluging the set in a chirping

G27343HP

C4701, c4705, c4506, c4505, q4851, c4853 all vented or shorted as soon as set was plugged into wall. Other parts on the 26v line may also be damaged. The cause was a shorted damper diode cr4402 putting 140v

sound was heard. Found a short across the horizontal output which turned out to be cr4402. Replacing cr4402 brought the set back to life but it had no vertical deflection. U4501 cured the vertical problem but

Replace cr4402 and all failed components on the 26v line.

Cr4402 shorted damaging u4501 and q4851.G27665

Page 27

Circuit Chassis Part Problem SolutionModel

Horizontal

CTC177 CR4402 Dead set cr4402 was shorted also found c4701

and c4505 on the 26 volt supply were shorted.

CTC177 R2709 Picture is narrow. voltage checks around u1001

indicated a problem at pin 16.the voltage was higher. traced problem to an open r2709 in the beam sense line that connects to pin 4 of t4401.

ctc177 trace Dead u3101 had voltages ok. Pin 15 had data

when power pressed. Pin 24 of u1001 had a waveform. Traced to an open trace between pin 6 of t4301 and l4401.

ctc177 cr4402 Unit came in with almost everything on the 26v

run line blown. The servicer replaced c4701, cr4701, r1908, c1909, and u1901 (audio). When he plugged the set in it blew all of these out again. We found a shorted damper diode, cr4402, allowing reg b+ into

Replaced cr4402 c4505 and c4701F27150SE

Replaced r2709.

Repair of trace repaired set.g27665wk

Replaced shorted cr4402.27gt614

CTC177 trace Overloaded pix. Agc too high. Co channel

CTC177 U1001 Slight distortion in tuner audio, aux audio is clean.

F25251WN

interference and some times snowy pix. Flexing the chassis the problems clear up. Found trace from pin 1 of the saw filter ( sf2301 ) to c7605 in the tuner area cracked.

All voltages are normal. Waveform at pin 3 of u1001 has a slight distortion in it. Replacement of u1001 fixed problem

The foil was cracked just as it enters the shielded area. C7605 is off q7601 collector.

Replace u1001F27631SF

Page 28

Circuit Chassis Part Problem SolutionModel

CTC177AF trace Snowy picture on all channels. Corrected broken trace between u1001-6 and

CTC177 GROUND G Tuning weak in all bands. Hi VHF was worse. All voltages at varactor and switching diodes chec

CTC177 U1001 Tuner Audio distorted. Aux audio is normal. All voltages checked normal. The waveform at

CTC177 Q7601 When changing channels, the picture would lock

25GT520

r2316.

pin 3

Replace shorted if amp, q7601. in the drift to snow. Monitoring the tuning voltages at the varactor diodes showed no change when the channel would drift off. Had a if signal inputted off pin 1 of u7301 and got the same results. Traced faul

CTC177 CBA Video distorted The AGC was too high. There was co channel

interfe

CTC177 C2307 SOL Tuner inop. All channels are snow. The AGC voltage at pin 12 of U1001 remains at

0V o

Page 29

Circuit Chassis Part Problem SolutionModel

ctc177 alignment Rf agc stuck at 8v all the time. Picture is going

into agc overload. Controlling the agc from an external source we got a good signal through. Servicer had changed u1001 and u3201. Adjusting the 4.5mhz trap in the eeprom corrected the agc problem.

CTC177 C1201 Audio buzz only on some channels. A VCR was connected to the aux-1 inputs. One of

CTC177ac Ground Weak tuning all bands all voltages at varactor and

ctc177 c1201 Audio buzz only on some channels. Servicer tried

F25190

switching diodes checked good. Checking if amp q7601 found 12vdc on coll. and 0vdc on base and emitter. Resistance from base to ground measured less than 1 ohm. Found that tech had bridged the base circui

changing c4129 to a 100uf but the symptom was the same. He then connected a vcr to the aux-1 inputs, tuned one of the bad stations on the vcr, and switched between tv and vcr listening to the same station

Eeprom adjustment.

Removal of solder bridge at grid 20f restored tuner

operation.

Changing this defective c1201 fixed the set.G26685wk

CTC177 SF2301 Video int. When video was input to the external ja All the voltages in the tuner checked normal. Subs

CTC177 TRACE Pix snowy on all channels. Found a broken trace between U1001 pin 6 and

R2316

Page 30

Circuit Chassis Part Problem SolutionModel

CTC177 C2307 Tuner signal missing. DC voltage on U1001 pin 12 measured zero volts

and

CTC177 L2302 Very snowy or no pix sound ok. Servicer found

that moving coil l2302 would make pix come and go. Replacing coil cured prob. Servicer said he has seen two of these.

CTC177 EEPROM AGC overload. The AGC was stuck at 8V all of the time. Controlli

CTC177 C2307 All channels are just snow. Agc voltage at pin 12

F25190SE

of u1001 remains at 0v on all channels. Checking pins 13 & 14 of u1001, we found less than 1v on both. Resistance from pin 14 to ground measured 800 ohms.

Replaced l2302G31641CK

Found and removed a solder splash from c2307 in

the circuit off u1001 pin 14.

CTC177 SF2301 Intermittent video input of video to the external

video jack worked okay. All the voltages in the tuner checked okay. Subbing IF signal no video. The saw filter was intermittent.

CTC177 C2313 No video from the tuner. Unit had a slick raster

not snow but had static for audio. Found 2vdc on pin13 of u1001. Disconnect pin 12 and video came back.

Replace saw filterF27351

C2313 checked good out of ckt. Replace c2313

and the unit worked fine.

Page 31

Circuit Chassis Part Problem SolutionModel

CTC177BH2 C2307 No tuner signal. Dc voltage on u1001-12

measured 0 volts and about 2 volts on pins 13 & 14 of u1001.

CTC177 C2313 Video missing from the tuner. There was 2VDC on pin 13 of U1001.

CTC177 L2302 The set had a very Snowy pix or Pix missing.

Audio

CTC177 Q2301 Unit had no voltage at pin 12 of u1001. On

checkin

Replaced leaky c2307 (near u1001-14).27GT613

Disconnecting p

Moving the coil (L2302) would make the picture

com

Q2301 shorted.

Keyboard

CTC177 17J STRIP Keyboard func inop Lifting the shunt capacitors, the keyboard would f

CTC177 JW427, JW Front panel cntrls. No menus were present when

the

There was a solder bridge from JW427 to JW428.

Rem

Page 32

Circuit Chassis Part Problem SolutionModel

Keyboard

CTC177 SW3410 Dead set. The standby supplies were normal. There was no data at U3101-15/16. Checking

U3101 p

CTC177 S3411 Power button inop. The TV would not turn on

with t

CTC177 PCB Functions inop. The set turns on when the volume uThere was leakage between pins 5 and 6 of

CTC177 C3106 The set Turns on/off intermittently. The voltage on pin 5 of U3101 was fluctuating up

Removing a solder splash near the power switch

(S3

U3101. R

Keyboard

ctc177 board Set turns on when vol up button is pressed. When

on channel up and down work but no other controls will operate. Found leakage between pins 5 and 6 of u3101. Removing components off of pins 5 and 6 and cleaning board removed leakage. Components were put b

CTC177 SW3431 Front panel inop. Measured a short from pin 2 to pin 5 on the front

Cleaned pcb.

Page 33

Circuit Chassis Part Problem SolutionModel

Keyboard

N/A

CTC177 C3103 Volume control inop. The volume down control

on th

CTC177 C4501, C45 Vertical will pull up from the bottom intermittent Pressing down on C4501 and C4503 will cause the

CTC177 Y7401 Tuner inop. The band switching was normal. The tuning

CTC177 C5002 CRT shorts. G1 voltage remained high when disconnected from

The microprocessor had been changed. Pin 7 of

U310

voltage

N/A

CTC177 C7404 Tuner inop The tuning voltage on the collector of Q7401 was

CTC177 C4506, U4 The neck of the CRT was burned off. Had apparent high current through yoke windings.

Page 34

Circuit Chassis Part Problem SolutionModel

N/A

CTC177 R7117 Tuner inop/Snow on screen Tuning voltage on Q7401 collector varied with

chan

CTC177 R7412 VHF low band was missing. High band was normal. The collector of Q4702 was at zero volts in low

CTC177 C4129 Audio buzz Changing C4129 from 10UF to 100UF (part

number 194

CTC177 GROUND Audio buzz when graphics or OSD were being

display

Resoldering the recommended ground connections

eli

N\A

ctc177bf c7304 Only snow. Q7401 volts changed to proper

voltage for channels we selected. However the voltages on u7301 were all wrong. Pin 8 had 3v and the chip was loading it down. Pin 7 had 3v (the only correct voltage) most of the pins had 0v. Checked resistance to

CTC177 R7117 No tuner signal and snow on screen. Tuning

voltage on q7401 collector varied with channel change. Found zero volts on q7102-g1.

Cleaned c7304 off of pin 5 of u7301 to repair the

set.

Replaced open r7117.F25651BL

Page 35

Circuit Chassis Part Problem SolutionModel

OSD

ctc177 c2708 Intermittent red components of osd. Off of

CTC177BE Q2701 No green in menus q2701 (g-osd driver) had

CTC177 R3311 No osd. found fsw signal missing at pin 39,

CTC177BG U1001 Channel number and vol. indicator were red,

g27687wkl

u1001 pin 40 c2708 was in backwards.

correct waveform at base and emitter, but the emitter waveform was not reaching the negative side of c2707, which should have been a direct connection. The trace between q2701-e and c2707 checked good up to the f

u1001.there was signal at pin 22, u3101.found an open r3311 (connected to pin 39 u1001).

menus were red blocks with no information displayed. U1001-40 (red osd input) had a normal waveform, but the dc level was 2v too high at

7.4v tech replaced u1001, and normal voltage and osd returned.

Replacing c2708 and putting in correctly solved

problem.

Soldering q2701-e repaired set.F27631SF

Replacement of r3311.

Replace u1001.G27341WK

Picture Tube

CTC177 CRT Pix green. The set had a faint green box in the pi Traced back from U1001 to the kine drive PCB.

When

ctc177 yoke Set would squeal when turned on. Horizontal

output, q4401, was shorted when the set came in. No scan derived voltages. The voltage would return and the squealing would stop with the horiz yoke unplugged. Set also drew 2 amps of current with the yoke plug

Replaced picture tube, bad yoke.25gt522

Page 36

Circuit Chassis Part Problem SolutionModel

Picture Tube

Pix/Pix

CTC177 CRT, Q440 When the set is powered on, it will Squeal followe Components off of the collector and the base circu

CTC177AF C5002 The raster is bright with retrace. The g1 voltage

was 180 vdc. We removed the socket. The voltage was still at 180 vdc. We removed r5007. We still had 180 vdc. At this point we removed c5002. It measured 14k ohms. The 180 vdc dropped to about 16 vdc.

CTC177 CRT When the set is powered on,the set will squeal

followed by a failure of the hot. checking the various items off of the collector and the base circuit checked normal.disconnecting the crt allowed the set to turn on and stay on.the servicer had a couple se

CTC177 CR2901 Pix flickers slightly in the background. Found a bad solder connection on the cathode of

Replaced shorted c5002F25251WN

Replacing the crt.F26251SE

Pix/Pix

ctc177ac R3116 No video. Found pin 22 of u2901 at 0v traced

back to u3101 pin 12 and found r3116 missing. Tech induced

CTC177 R7306 Cable channels 2 through 48 tune poorly. Tuner. Checking tuning voltages found junction of

Installed r3116

CR7302

Page 37

Circuit Chassis Part Problem SolutionModel

Pix/Pix

CTC177 R2908 No pip or box for the small picture. Main picture

was ok. Measuring voltages we found the voltage low on u2901-20.

CTC177 C2918 PIP inop. The set had been hit by lightning and U2 Pins 1, 26, 25, 13, 18, 7 and 9 of U2901 were at z

CTC177AE R2909 No video. Traced video signal to u2901, but had

no output. Checking pins 20-22, we found data information on 20 and 21 but pin 22 was at .3 volts. U3101 pin 12 was at 4.8 volts. Following the line up to u2901 we found one side of r2909 unsoldered. Resolde

CTC177 R2908 PIP missing, the box for the small picture was mis Found the voltage on U2901 pin 20 was low.

Replaced open r2908.F25190FE

Resolder r2909G26681CK

R2908 w

Pix/Pix

CTC177 SOLDER R Pix flickering The flickering resembled a video picture of a TV p

CTC177 TRACE Video missing Video was lost at PIP IC. Pins 11 and 12 of

U2901

Page 38

Circuit Chassis Part Problem SolutionModel

Pix/Pix

CTC177 R902 Normal color on big picture, has color sync

CTC177AE C2918 Set hit by lighting, u2901 and u2902 had been

CTC177 SOLDER Good main pix video, pip video looks like a double

CTC177 R2902 The set produces normal color on the big picture, R2902 (connecting to pin 24, U2901) was

F27671

problem on pip. While examining circuitry at u2901, found r2902 (connecting to pin 24,u2901) was mounted incorrectly on the board (90 degrees off) not completing the circuit.

replaced. Found pins 1, 26, 25, 13, 18, 7, and 9 to be 0 volts, which was due to c2918 being shorted off the 14.318mhz crystal.

image. In checking pip micro, u2901 tech noticed a solder bridge from pin 41 (ground) to pin 42 (a4 line from sram u2902). Removing the solder bridge fixed the set.

Removing the mispositioned r2902 and installing

a new one fixed the set.

Replaced c2918

Remove solder bridge from pins 41 and 42 of

u2901, pip micro.

mounted in

Pix/Pix

CTC177 R2932 Pix missing. Had video into U2901 at pins 4 and 8, Pin 6 of U2901 measured 4.3V. The DC on pin 4

was

CTC177 U2903 Video missing. The set had video to the D-PIP IC bThe VDD to IC2901 (the D-PIP pins 11 and pin

43) s

Page 39

Circuit Chassis Part Problem SolutionModel

Pix/Pix

ctc177 trace No video. Video lost at pip ic. Pins 11+12 of

u2901 had 5.4v. Pin 43 had 2.5v. Found open trace between fb2901 and 5.4v source.

CTC177AE R2925 No small picture in the pip mode. The osd would

indicate that pip had been selected, but there was no small picture or frame for the picture. At u2901, we found there was no sync signal or dc voltage at pin 19. Checking through the sync amps, q2904 and q2

CTC177 R2925 Small pix missing in PIP mode. The OSD would

indic

CTC177 CR2902 Pix flickers slightly in background. Servicer said

he found the cathode of cr2902 (off u2903 5v regulator ic pin 2 to ground) not soldered.

Repaired open trace.f31671se

R2925 in the base circuit of q2904 had been

bridged to ground while previous soldering of

shield tabs was performed. (loc 4-j). Removing the

short restored the small pip picture.

There was no sync signal or DC voltage at pin 19

Resolder cr2902F27671

Pix/Pix

CTC177 R2909 Video missing Traced the video signal to U2901, but had no

outpu

CTC177 R2932 No pix. Had video into u2901 at pins 4 & 8 but

not out at pin 6 u1001,u2901,u3201 had been replaced. Dc on. Pins 4, 6 were at 4.3v. 5 volts is fed to a voltage divider ( r2931 and r2932 ) to the anode of cr2904 off pin 4-u2901. We found 5v on the anode,

Replace open r2932 10kG27687

Page 40

Circuit Chassis Part Problem SolutionModel

Power Supply

CTC177AF2 Q4105 The set intermittently won't turn on. If you have

it on and turn it off it may not come on. If you remove the ac and count to ten reconnect the ac, the set won't turn on. The voltage at u3101-20 was changing from 4.8 to 6.6 vdc. Found that q4105 was leaky

CTC177BG C7109 Coil l4101 off the secondary of the flyback had

CTC177AM2 C4135 U4101 would short out. After replacement the set

CTC177 CR4104 This set had weak, transparent osd like has been

G27341wk

become very hot. Taking a resistance measurement to ground there was a dead short on the 12v e run source. Lifting jw 420 removed the short which is used to supply 12v to the tuner. Upon closer inspection a

ran for about 5 minutes but on bright scenes the picture would pull in. This caused the regulator chip u4101 to blow out again. After replacing u4101 we found that the regulated b+ was being sucked down and

reported before, with the add. symptom of no video muting at channel change. It was possible to see the hor. freq. Change and lock back in as channels were changed. Cr4104 was zenering at 5vdc and the 5v st

Replaced q4105F26251E

Removing the solder splash across c7109 resolved

the problem.

Replacement of c4135 resolved the problemG27304DT

Replace cr4104F25190se

Power Supply

CTC177 CR4104 No on screen display the 5 volt standby was

reading 4.7 volts which is low but everything else was working on the set.

ctc177af3 cr4109 Reg b+ would change from 140vdc to 120vdc. The

pix would change from a full size picture to a postage stamp picture. It would change sizes slowly.

Cr4104 which is 5.6 volt diode was reg. At 5 volts.F27150SE

Found cr4109 defective.

Page 41

Circuit Chassis Part Problem SolutionModel

Power Supply

CTC177 R4105 The set makes a buzzing sound in the off mode.

Reg b+ is high the set worked ok but when you turn it off the regulated b+ measured 215 vdc at t4401-3. The servicer had replaced c4103. The voltage at u4101-2 & 6 was about right. On pin 6 side of c4102 the

CTC177AF C4108 Piecrusting- sometimes in bands, sometimes over

whole picture. Checking power supplies, tech found c4108 at 100uf, should be 1000uf.

CTC177 C4108 Piecrusting. Sometimes in bands, sometimes over thChecking power supplies, found C4108 at 100uf -

CTC177aa3 JC403/411 Dead set. Had no supply to u1001 pin 22. Found a

open between jc403 and jc411, which is supplying the 12volts stby 2a to pin 22 of u1001.

Resoldered r4105.F26631SE

Replacement of c4108 cured problem.F26251ET

Replaced defective jc411.

Power Supply

CTC177 CR4115 Dead set. All standby voltages were key. Micro

was working okay. Pin 22 of u1001 was at .4 vdc.

CTC177AD C4127 Regulated 140.5v goes to 300 volts and vents

c4107. Tech found c4127 value checked ok but, esr was high.

Found diode cr4115 off pin 22 was shorted.31GT657

Replaced c4127 (near u4101-1).G27341WK

Page 42

Circuit Chassis Part Problem SolutionModel

Power Supply

ctc177h2 cr4701 No vertical. No b+ to u4501. No 26v. Cr4701 checked good but replacement fixed set.j20530bl

CTC177 Q4105 Remote would not function most of the time.

CTC177 FIX Dead set due to the 5 volt supply down to 2.9volts Removed R4108 and cleaned the area under the

CTC177BG L4102 Intermittently tv was dead. Corrected bad solder connection on l4102 (on the

F25215WT

Ir3401

CHASSIS:

G27343HP

Replacement of Q4105 restored remote operation

compo

140v line).

Power Supply

CTC177 trace Intermittent dead, changing chans, bringing up

CTC177 CR4701 Vertical missing. There was no B+ to U4501 and

F27671

menus etc.

Found the foil that connects to jw447 and jw448

cracked. (jw448 is off the emitter of q4103 the 5v

stby2 source)

CR4701 checked good, but was defective.

Replacing

Page 43

Circuit Chassis Part Problem SolutionModel

Power Supply

CTC177 COIL WIR Streaks in pix. Digital noise in picture. The degaussing coil wires were laying too close to

CTC177 C4105 Vertical was pulled down approximately one inch frThe 140V line was noisy. C4105 was defective.

Repl

CTC177 C4103 Dead set.the secondary of the power supply (the

143volt especial ly) was over 250 volts. checking the circuit at the chopper regulator ic, found an open capacitor at pin 6, u4101.

CTC177 C4103 Dead set c4107 vented. Reg 140 line high (over

200) while checking the feed back circuit of the regulator he noticed that c4103 off pin 6 of u4101 was missing. Replacement brought 140 v line down to normal.

Replacement of c4103 fixed the set.F26631SE

Replace missing c4103F27671SE

Power Supply

CTC177 C4135 Dead set. U4101 would short. After replacing

U4101

CTC177 Q4105 Intermittently, the set Won't turn on. The voltage at U3101 pin 20 was changing from

The regulated B+ was being pulled low by a leaky C

4.8V

Page 44

Circuit Chassis Part Problem SolutionModel

Power Supply

CTC177 C7109 Dead set. Coil L4101 off the secondary of the flyback had

CTC177 CR4703 Dead set. The 12V supply was down to 9VDC. The 5V

standby wa

CTC177 CR4109 Picture changes size. The picture would change fro Regulated B+ was changing from 140VDC to

120VDC. C

CTC177 TRACE No vertical deflection, Line toward the bottom of Repaired open trace between r4106 & c of q4101.

Power Supply

ctc177aa2 cr4106 U4101 shorts from pin 11 to 9 immediately after

CTC177 CR4106, U Dead set U4101 shorts from pin 11 to pin 9 immediately

25gt506

plugged in. Found that the 140 volt line on the secondary was shorted to ground. Cr4106 was shorted.

Replaced cr4106. I have had this diode bad before,

but this is the first one that was causing the

regulator ic to short.

afte

Page 45

Circuit Chassis Part Problem SolutionModel

Power Supply

CTC177 C4124 Dead set. Set ticks when turned on. The 140V is normal until set is turned on. Then it

CTC177 CR4104 OSD looks transparent. Found B+ on U3201 was at 3.8V and CR4104

zenering

ctc177cc c4124 Set tics when turned on. The 140v is ok until

CTC177 C4119 Tuner would not tune channels 14, 15, 16, 17, or 3 Tuner voltage would only get as high as 9.8V. The

31gt657

turned on. Then it pulses between 100v and 140v. Looking at the waveform at pin 3 of t4101 we saw it to be normal in stand by and it would make an attempt to shift towards the run waveform but quit half way t

Found c4124 off of u4101 pin 7 to be poorly

soldered at one end. Soldering the cap repaired the

unit.

Power Supply

CTC177BE T4101 Buzzing sound heard from the set in the standby

CTC177BE Q4105 Dead. The vdd on u3101-20 measured 2.5v and

25GT506

mode. At 110vac, standby b+ measured 189v at cr4106 cathode. Scoping the anode of cr4106, the technician described the waveform as a pulse followed by a ringing. With pin 12 of t4101 unsoldered, the buzzing

the reset pin 1 was 5.4 volts. Voltage on q4105-b measured 5.4v, but the emitter was 2.5v.

Substituting t4101 from another chassis restored

normal operation.

Replaced q4105 five volt regulator.F27631SF

Page 46

Circuit Chassis Part Problem SolutionModel

Power Supply

CTC177 L2704 No vertical, servicer had replaced u4501 (vert

output) and rn 4501. On rn4501 (7) the 7.6v source was missing. Measuring the q4101 (e) 7.6v reg., There was 7.6v present but it was not there on one side of l2704. Using an ohm meter l2704 checked open.

CTC177 CR3111 Dead tech had found open connection at tuner

CTC177AF3 R4135 C4105 vents. The reg b+ is 300 volts. Found R4135 open. Replacement restored

ctc177aa CR4101 Osd looks transparent. Found b+ on u3201 at

25GH350

shield near e116 and repaired all shield grounds. The tv was still dead. The 12v stby line was at 0v. The resistance to ground on the line was less than 1 ohm. Following the 12v stby line and unloading various

F27252GYFE1

3.8v and cr4104 zenering at 4.6v. Heating cr4104 caused the osd to dissappear.

Replace l2704

This diode is not on our ctc177 prop, only on the

commercial chassis. Clearing the solder bridge

returned operation to normal.

operation.

Replaced cr4104.

Power Supply

CTC177 FB4110 Intermittent tuner, no picture or sound with

snow. Voltage on collector of q7401 dropped to zero when the tuner signal disappeared. Tracing we found we were losing the 33v to the tuner.

CTC177 C4127 High reg B+ Regulated 140.5V goes to 300V and vents C4107.

Corrected bad solder connection on fb4110 at 19i.F25190

Fou

Page 47

Circuit Chassis Part Problem SolutionModel

Power Supply

CTC177 CBA TRAC Dead set. When attempting to turn the set on,

U310

CTC177 CR4104 No osd, no remote response, picture and sound ok.

But, horizontal sync takes a while to lock up after channel change. Voltage at cathode of cr4104 for 5v standby measured 4.8 volts.

CTC177 CR4704 Set had no vertical and no audio. Cr4704 off pin 9

of the ihvt was shorted and r4702 and r4517 were open or stressed.

CTC177 Digital noise or streaks in pix Degaussing coil wires too close to tuner. Redress

The DC input to U4102 was 15V and had 40Vp-p

when

Replaced cr4104.F26633

Replaced cr4704, r4702, r451727GT613

wires.

Power Supply

ctc177af c4119 No channels 14, 15, 16, 17 or 32+. Tune volts

would only get as high as 9.8v. 33v line was 10.8v by process of elimination found c4119 to be leaky.

CTC177 CR4704,R4 The set would Shutdown. It appeared to be an

over-

Replaced c4119 and repaired set.25gt522

Traced the fault to a shorted CR4704 (12V run

sour

Page 48

Circuit Chassis Part Problem SolutionModel

Power Supply

CTC177 R4104 Dead set All voltages on U4101 were at zero except pins

CTC177 R4104 Dead. All voltages on u4101 were near zero

except pins 11 & 12 which were 168 volts.

CTC177 C4103 Dead set C4107 had vented. The regulated 140 line was

CTC177 C4103 The set had a high pitched Squeal when the TV

was

Replaced open r4104 (u4101-4).F25190SE

high

When the set is in standby, the 143 volts at the s

Power Supply

CTC177 Q4105 No osd. B+ to pin 20 of u3101 was low (3.8) and

checking back at the 5v standby supply we found q4105 had a b-e short.

ctc177 q4105 2 seconds after turn on the set shuts down.

25gt542

Repeats when power pressed again. Only pulses one time and quits. Found reset line at 4.8v. 5v line was at 3.3v. Q4105 had 3.3v at b and c.

Replace q4105F25190SE

Replaced q4105 with e to b short and repaired the

unit.

Page 49

Circuit Chassis Part Problem SolutionModel

Power Supply

CTC177 CBA Dead set int. When changing channels, bringing up The foil that connects to JW447 and JW448 was

crac

CTC177 CR4704 Set shuts down at turn. found it to be over current

shutdown. Traced the fault to a shorted cr4704 (12v run source). have found r4702 and r4517 opened as well. the set worked fine after these parts were replaced.

CTC177 U2903 Video missing. OSD normal. The video was traced from U1001 to the PIP chip

CTC177 R4104 Dead set following a brief power disruption. The p R4104 (at pin 4,U4101) was open. Replacing

Replaced cr4704, r4702, r4517.27GT613

R4104 r

Power Supply

CTC177 Q4105 OSD missing The B+ to pin 20 of U3101 was low (3.8V) and

check

CTC177 C4108 Dead set The 12V standby voltage was low on U4102 pin 3

Page 50

Circuit Chassis Part Problem SolutionModel

Power Supply

CTC177 R4517 Vertical problems and/or Snowy pix. The picture would become snowy and display

various

CTC177 C4706 Repeat failure of cr4704. Replacement diode only

lasts a few seconds. Found open c4706.

CTC177 CR4106 Dead set dead set, no 140 regulated b+. Found

cr4106 the 140vdc rectif ier shorted

CTC177 CR4704 The set had no Vertical and the Audio missing. CR4707 off of pin 9 of the IHVT was shorted and

Replaced c4706.

Replaced cr4106F27631SF

Power Supply

CTC177 R4104 Dead. All voltages on u4101 were zero except

pins 11 and 12 had 167 volts. Found r4104 open, not supplying the start up voltage to pin 4 of u4101.

CTC177 CR4104 Very weak osd the picture was very good, you

could just see the osd. The brightness control would control the picture but the osd didn't change. The voltage at the cathode of cr4104 was

4.9 vdc it should have been 5.6 vdc

Replaced r4104F25190

Replaced cr4104F27150SE

Page 51

Circuit Chassis Part Problem SolutionModel

Power Supply

CTC177 Q4105 Two seconds after turn on the set Shutdown. The faThe reset line was at 4.8V. The 5V line was at 3.3

CTC177 CBA OSD missing The base of Q2701 had a 0.5Vp-p signal with no

gai

CTC177 CR4104 No osd u3201-8 voltage was down to 4.2 vdc the

source of the voltag e is clamped cr4104 in the base of q4103. The 5.6 volt zenier diode was 5 vdc

CTC177 CR4106 Dead set There was no 140 regulated B+. CR4106 (the

Replaced cr4104

140VDC

Power Supply

CTC177 C4103 Buzz from the set when in the standby mode. The waveforms were not as they should be (very

dis

ctc177af c4105 Vertical down 1" from top. Foun 140v line noisy. Replaced c4105 to repair set.25gt522

Page 52

Circuit Chassis Part Problem SolutionModel

Power Supply

CTC177 R4129 Dead set The voltage at pin 4 of U4101 was at 16VDC and

ctc177 e116 Dead. Q4105 + 3 had 2.5v e. U4102 had 10v pin

1 and 7v pin 3. Subbed in our own 12v on pin 3 of u4102 with set unplugged. Found 7v on q4105 e and 7.5v b. Cr4104 had 7.5v cathode and 2v anode. All grounds on the tuner had been reworked but the pad at e116

CTC177 E116 Dead set Q4105 had 2.5V on the emitter. U4102 had 10V

ctc177 R4129 Dead set voltage at pin 4 of u4101 was at 16vdc

and pin5 of u4101 was also at 16vdc.

A jumper from e116 to tuner shield fixed the set.f25190se

on pi

Replaced open r4129 100k resistor

Power Supply

ctc177 c4103 Set squeals when turned off. Found c4103 with

one end not soldered. C4103 is located off of pin 6 of u4101.

CTC177 CR4703 Dead. 12v supply down to 9vdc. 5v standby down

to 3vdc

Soldering c4103 repaired set.f27671se

Found cr4703 leaky. (off pin 10 t4401)

Page 53

Circuit Chassis Part Problem SolutionModel

Power Supply

CTC177AF C4124 Tv makes ticking noise after pressing power

button and cannot be turned off. Found 140v to pin 3 of ihvt cycling between 100 and 125 volts. Leaving tv turned off the regulated b+ was 135v which normally measures 146 volts.

CTC177 CR4104 The set had very weak OSD. The picture was very goThe voltage at the cathode of CR4104 was

ctc177 trace No video no audio. Screen was black. R4517 had

12v on one side, 5v on the other, was hot and smelled funny. U4501 had 1.5v on pin 5. Rn4501 had 5v on pin 5 and 0v on pin 7. We floated pin 5 of u4501 and voltages came up except the 7.5v. The problem was t

CTC177 C4127 When plugging the set in after it had been

unplugged overnight the power supply would cycle 3 times until it would finally run in standby. C4127 which is located off from pin 1 of u4101 was the cause.

Replaced open c4124 (u4101-7).25GT522

4.9VDC. I

Repair of trace returned set to normal.g26685wk

Replacement of c4127 resolved the problem.

Power Supply

CTC177 c4108 Dead set. Found 12v standby voltage low on

u4102 pin 3 in the power supply circuit. Input voltage on u4102 pin 1 should be between 18 and 20vdc. Input level was down to 11.3 with ac level of about 2v p-p.

CTC177 COPPER T Video missing/Audio missing. The screen was black. R4517 had 12V on one side and 5V on the other.

Replaced open c4108

R45

Page 54

Circuit Chassis Part Problem SolutionModel

Power Supply

CTC177 R4136/C41 C4107 vents and reg b+ at 400vdc c4107 open

and the regulated b+ about 400 vdc. R4136 which is only found in the later schematics. This is a smd located at 19n on cba. (10 ohms) was open.

ctc177 trace No osd base of q2701 had .5v p-p signal with no

gain to the emitter all the dc voltage levels on q2701 where ok.. 7.6v supply to r2712 was at

9.6v. Found open trace between r4119 and cr4101.

CTC177 CR4104 OSD inop The 5 volt standby was 4.7 volts. Everything else

CTC177 CR3111 Dead set The set had an open connection at the tuner shield

Replaced r4136

Restored trace between r4119 and cr4101

Power Supply

CTC177 R4104 Dead set following brief power disruption.the

power supply was completely dead.found an open r4104(at pin 4,u4101). The servicer has seen at least 8 to 9 units with the same fault.

CTC177 C4107 Horizontal jitter and the pic pulls when the

brightness goes up unit had horizontal jitter and the picture would pull in on the side as the brightness goes up. Found that c4107 on the regulate d b+ had and open lead. (same as an open capacitor.)

Replacement of r4104 in each case repaired the

set.

Replaced c4107G27685HP

Page 55

Circuit Chassis Part Problem SolutionModel

Power Supply

CTC177 R4119 Vertical would intermittently drop down. found

7.6 run source varying at pin 32, u1001.

CTC177 CR4104 OSD missing/no Remote response. The picture

and so

CTC177 C4109 Squeals at plug in, servicer had replaced u4101 for

a dead set. If unit was left plugged in u4101 would fail. Resistance checks didn't show a fault. With the regulator bypassed and ac set to 25 volts c4109 started at arc and smoke as the ac was increased.

CTC177 C4007 Standby voltages high, 140 volt was at 180 volts.

Servicer said the raw b+ had a lot of trash on the line. Jumping out c4007 cleaned up the line and lowered the b+ to 140 volts

Resolder r4119 (off the base of q4101,7.6 volt

regulator).

The voltage at the cathode of CR4104 (for 5V

stand

Replace c4109 in regulator circuit.

Replace c4007

Power Supply

CTC177 CR4104 OSD missing U3201 pin 8 voltage was down to 4.2VDC. The

source

CTC177 C4107 Horiz jitter and the Pix pulling in when the brigh C4107 on the regulated B+ had an open lead.

(Same

Page 56

Circuit Chassis Part Problem SolutionModel

Power Supply

CTC177 R4135 Plugging in ac c4105 and c4107 overheat. Replaced open r4135 (t4101-7).G26638

CTC177 T4101 Buzz in standby mode. At 110VAC, standby B+ measured 189V at

CR4106 cath

CTC177BF CR4109 Poor regulation. Picture width would decrease with

high video content in picture reg. B+ would vary from 140vdc to as low as 123vdc. U4101 had been changed. Checking components in regulator circuit, cr4109 checked leaky in the forward direction. Tech repl

ctc177 c4103 Buzz from set in stand-by mode. Wave forms

were not as they should be. Very distorted. Voltage on pin 2 of u4101 was slightly low. Very little waveform.

Replacement of cr4109.F27671SE

Inspection showed very poor solder connections

on c4103. Resoldered. No buzz

Regulator

Remote Con

CTC177 T4101 Low regulated b+ T4101 pin 1 to pin 3 a high resistance.

CTC177 IR RECEIV After the set powers on, the Channels scan upward. There were signals out of pin 1 of U3101. The

volt

Page 57

Circuit Chassis Part Problem SolutionModel

Remote Control

RGB

CTC177 IR3401 Set would turn on and go into autoprograming and tJumped 4.6 volts to pin 1 of u3101 and the set worCHASSIS:

CTC177AF2 IR After the set powers on, the set started to scan up

channels. Found signals out of ir receiver at pin 1,u3101 and the voltage at pin 1 was 0v. pin 1 should be 4.6v. isolated problem to the ir receiver.

CTC177 Q5004 No video. Original problem was dead set, with

defective ihvt. Servicer had replaced u3201 and u3101 but couldn't get any on screen display to set up the alignments. Servicer had flat black screen with audio and no osd. Checking crt setup we found that th

CTC177 Q5001 Color appears to be breathing,with the tint

changing. Scoping signals from the t chip did not reveal any problems. Found that the signals at the collector of q5001 were varying as the condition symptom developed.

Replacement of the ir receiver.

Found b-e open on q5004 on kine socket cba

Resoldering q5001 on the kine drive cba.

RGB

CTC177 YOKE The set would Squeal when turned on. The horizontal output, Q4401, was shorted when

the

CTC177 Q5001 Color changes and the tint changes. Scoping signals from the T chip did not reveal any

Page 58

Circuit Chassis Part Problem SolutionModel

RGB

Special Effects

CTC177AA3 R5012 No red. Resistor r5012 in the emitter of red drive

q5001 had increased from 130 ohms to over 2000 ohms. Red drive transistor was turn off.

CTC177 Q5004 Bright screen with retrace. Crt had been replaced

the cathodes measured between 40 to 50 vdc. We went to q5003 the collector was 41, base 2.1 and emitter 1.5. Then we checked q5004 the emitter base and collector were all 0 vdc. (shorted)

ctc177 c5004 Pix too bright. Could not get pix brightness down

using the screen control. Found c5004 off of base of q5004 shorted.

CTC177 Q2701 Green missing in menus. Q2701 (G-OSD driver) had correct waveform at

Replaced resistor r5012.

Replaced q5004F25651BL

Replace q5004.

base

Special Effects

Sync

CTC177 Q3303 Closed caption missing. OSD was normal. Found no video at U3101 pin 13. Tracing from

U1001

CTC177 C2308 Pix snowy/Horiz sync missing. Pin 6 on U1001 was down to 2VDC. Found C2308

was c

Page 59

Circuit Chassis Part Problem SolutionModel

Sync

System Control

CTC177 C2308 No horizontal sync and snowy pix. Pin 6 on

u1001 down to 2vdc. Found c2308 cracked.

CTC177 U3201 Red distorted/Green smears U3201 was defective. Replacing U3201 repaired

CTC177 R2711, C27 No Autoprogramming in the cable mode. In the

off-a

CTC177BD C3103 Chassis will not power on. all standby voltages

checked normal. Found the voltage on pin 7, u3101 1.9 volts. it should be 4.7 volts. Traced fault to a leaky c3103.

Replace c2308 . This cap is mounted on the

chassis where the rails contact the chassis. Sliding

the chassis in and out can cause the cap to become

cracked.

the

Checking Q3301 off pin 39 of U3101, there was

only

Replacement of c3103.

System Control

CTC177 R3132, R31 Dead set. Reset voltage was missing at U3101 pin 1R3132 and R3133 were open. Replacing R3132

and R31

CTC177 connection The video and audio will intermittently go out,

and change channels by itself. this condition does not last. the set may clear up and work for extended periods. The shield that borders the micro had a tab that was not soldered

To the board at location j3.

Page 60

Circuit Chassis Part Problem SolutionModel

System Control

ctc177be c3102 Dead. U3101 pin 5= 4.5v, pin 15 +16 = 2.5v.

U3201 pin 5 = 2.5v, pin 6 = 0v. Pin 6 of u3201 measured 300 ohms to ground. Found shorted c3102. Removed and set worked.

CTC177AM2 C3113 Intermittently the degauss relay would chatter. Found c3113 (off pin 1 of u3101) the ground end

CTC177 TRACE Video missing/OSD missing The horizontal pulse to U3101 pin 26 was

CTC177 U3201 Video int U2901 would lose all voltages on all pins except 2

G25361BK

Replace c3102.f27351wn

not soldered.

missing.

System Control

CTC177 C3310 OSD rolling vertically. The waveforms at pins 24 and 25 of U3101 were

norm

CTC177 Q3101, Q3 Dead set. All voltages on U3101 were normal. No data

appeare

Page 61

Circuit Chassis Part Problem SolutionModel

System Control

CTC177 JW408, JW Dead set. U3101 and U3201 had been replaced. Pins 5 and 6 of U3201 measured 2.5VDC. There

was a

ctc177 u3201 No vertical. Line across screen was dim. Pin 16

of u1001 was at 7v. No output on pin 17. Voltages on u4501 looked ok.

CTC177 U2901, U3 External Video missing. Normal tuner video was

pre

CTC177 U3201 The OSD was stretched and shifted to the left. Pin 6 of U3201 (data line) was compressed to

Replacement of u3201 repaired the set.25gt536

U2901 was defective. Replacing U2901 still did

not

3.5Vp

System Control

CTC177 U3101 Dead set. U3201 and U3101 would intialize

properly

CTC177 C3307 OSD missing U1001 had waveforms at pins 40, 41 and 42 when

All the voltages around U1001, U3201 and

U3101 wer

the

Page 62

Circuit Chassis Part Problem SolutionModel

System Control

CTC177 U1001 OSD red. The channel number and volume

indicator w

CTC177BE Solder No osd, u1001 had waveforms at pins 40, 41 and

42 when menu was button was pushed. Checked pin 39 of u1001 and found no change at all. Had servicer go to pin 22 of u3101 and he noticed a solder bridge across c3307. Removing the short returned normal osd.

CTC177 Q3301 Autoprogram inop. U3101 pin 39 had no sync pulse. Q3301 had a

CTC177 U3101 Dead set The B+ and clock signal was normal. The clock

U1001 pin 40 (red OSD input) waveform was

normal,

Remove solder bridge from c3307.N\A

broken

and

System Control

CTC177 U3201 Spanish mode could not be turned off. U3201 was defective. Replacing U3201 repaired

the

CTC177 U3101 Pix red on some channels. Other channels were

fine

U3101 was defective. Replacing U3101 repaired

the

Page 63

Circuit Chassis Part Problem SolutionModel

System Control

CTC177 SOLDER S Dead set/Won't power on. Standby supply was

normal

ctc177 u3101 Dead b+ and clock ok. Clock and data lines

constantly active when we checked but servicer said he checked the data later and it was missing.

CTC177 T4401 The TV would Power off/on intermittently. Repairing bad solder connections on T4401

CTC177 TRACE Controls inop/Video missing/Audio missing.

U3201,

Followed the problem to the enable line. Pin 14 of

Replacement of u3101 repaired set.f25190se

(IHVT) p

U1001 pins 53 and 54 were at 4.7V, but pin 52

was

System Control

CTC177 CR3302 OSD rolling. There was no sync at pin 25 of U3101. Replacing

ctc177 r3316 No closed caption. Osd ok. Found video on pin

13 of u3101 ok. Pin 25 of u3101 had 1.5v instead of .25 with 21v p-p instead of 5vp-p. Found and replaced an open r3316.

Replacement of r3316 off of pin 25 repaired set.f25651bl

Page 64

Circuit Chassis Part Problem SolutionModel

System Control

ctc177 q3101 Dead set. Reset line on u3101 0v. Replaced leaky q3101 reset transistor.27gt613

CTC177 trace Intermittent shutdown. Intermittent snow at

CTC177 trace Keyboard not working. If you lift the shunt

CTC177 JW436, R7 Tuning missing in cable mode. OSD missing. Set

F25190SE

times,channels changing.

capacitors the keyboard would function inspection of the cba revealed the trace at 17j where r3332, c3303 & r3314 solder in was lifted up and twisted and shorted to the listed components. Redress and repair of

had

Repair broken foil pattern at location e116 to

tuner shield ground foil.have seen many of these

chassis with same faults.

Repaired cba trace at 17j27gt613

Found Q7403 and Q7404 were leaky. Replacing

them r

System Control

CTC177 U3201 Audio missing. The Speaker Mute was activated. U3101-29 was high at 5VDC activating the

speaker m

CTC177 Q3101 Dead set Pin 16 of IC U3101 was at 0VDC. Pin 15 was at

4.8V

Page 65

Circuit Chassis Part Problem SolutionModel

System Control

CTC177 R3104 Dead set unless power button is pressed immediatel Found R3104 was open. Replacing R3104 restored

nor

CTC177 C3103 Dead set The microprocessor and EEPROM had been

replaced fo

CTC177 U3201 No sound. With service adjustments tech was able

to correct horizontal frequency, vertical size and vertical dc. No sound was caused by 5v on u310129 spkr mute.

CTC177 connection No autoprograming in cable mode. In air mode the

F25251WN

unit programmed fine. Checking q3301 off pin 39 of u3101 found only 1.2 vdc on the collector. Checking the base of q3301 for signal we had none. Following the circuit back to r2711 and c2718 found a solder

Replaced u3201.25GT506

Removal of the solder bridge on r2711 and c2718

repaired the set. During resoldering of the ground

tabs the servicer could cause this problem.

System Control

CTC177 Q3305 OSD missing There was no signal at U3101-18 and only 1 volt

CTC177 BROKEN F Int shutdown. Intermittent snow at times.

Channels

Repairing a broken foil pattern at location E116 t

Page 66

Circuit Chassis Part Problem SolutionModel

System Control

CTC177 U3201 Vertical foldover at top. Bottom was pulled up 3 i Pin 15 of IC4501 was at 18V and pin 16 of

U1001 wa

CTC177 U3201 Vertical missing. Both U1000 and U4501 had both been replaced.

U3201

CTC177 U3201 Very slow Channel change in the cable mode. Off-aiThe AGC at pin 12 of U1001 would wander high

and l

CTC177 SW3410 Dead set-- standby supplies normal, no data at

u3101-15/16. U3101 had been replaced, and grounds repaired. Checking u3101 pins 5-8: 5, 7, 8 were normal at 0,5,5 vdc but 6 was .6vdc when it should have been 5vdc. Lifting pin 1 of sw3410 allowed pin 6 to g

Replaced leaky sw3410F25651bl

System Control

CTC177 C3312 Remote inop Pin 3 of U3101 was at 2.5VDC. C3312 (off of pin

CTC177 U3201 The set Powers on when AC is applied. Pressing

the

Replacing the EEPROM, U3201, repaired the set.

Page 67

Circuit Chassis Part Problem SolutionModel

System Control

CTC177 R3316 No closed caption. The OSD operated normally. The video on pin 13 of U3101 was normal. Pin

25 of

CTC177 U3201 Bar in pix on UHF channel 50 only. Found U3201 was defective. Replacing U3201

repaire

CTC177 U3201 The set picks up only two channels, there are no

CTC177 C3126 Dead set Micro was not running. The reset line was low.

F27671

menu functions , there is no color. checking the vcc at u3201 checked normal. Typical clock and data activity present as compared to other sets.

Replacement of u3201.the tech had confirmed

two repairs of the same chassis with the same

problem.

The

System Control

CTC177 R3120 Dead set Found no reset voltage on pin 1 of U3101. Traced

CTC177 U3201 Tuning inop. The set picks up only two channels. TThe VCC at U3201 checked normal. Typical

clock and

Page 68

Circuit Chassis Part Problem SolutionModel

System Control

ctc177 c3104 Pushing the menu button gives you part of the set-

up menu. Pushing it again makes the menu go away, instead of running thru the various functions. Found that shorting pin 8 of u3101 directly to ground would give us the proper menu. Lifted the smd capacit

CTC177 C3201 Dead set Pin 5 of U3101 was at 4.5 volts. U3101 and

CTC177 CR3302 Osd rolling. No sync at pin 25 of u3101. Replaced shorted cr3302 off pin 25 of micro.

CTC177 C3113 Degauss relay chatters intermittently. Found C3113 (off pin 1 of U3101) had a bad

Replaced leaky c3104.x25101gs

U3201 h

This is a three legged smd at location i-13.

solder

System Control

CTC177 C3103 Won't power on. All standby voltages checked

norma

CTC177 U3101 OSD compressed. Replacing the EEPROM did not

corre

Found the voltage on pin 7 of U3101 was at 1.9V,

Found U3101 was defective. Replacing U3101

repaire

Page 69

Circuit Chassis Part Problem SolutionModel

System Control

CTC177 C3102 Dead set U3101 pin 5 was at 4.5V, pins 15 and 16 were

both

CTC177 U3101 OSD malfunction. The channel 4 (OSD) flashes

on an

CTC177 CBA OSD inop Horizontal and vertical sync was present into

CTC177 ALIGNME Vertical foldover at top and stretched out on the Pin 5 of U4501 was at 19 volts. Entered the servic

Replacing U3101 repaired the set.

U310

System Control

CTC177 C3104 Menus missing. Pushing the menu button produced paShorting pin 8 of U3101 directly to ground would

CTC177 C2708 Intermittent Red components of OSD. C2708, off of U1001 pin 40, was defective.

Replaci

Page 70

Circuit Chassis Part Problem SolutionModel

System Control

CTC177 U3201 No Vertical. The picture displayed only a line acr Pin 16 of U1001 was at 7V. There was no output

CTC177 C3115 Dead set. The set will not turn on. The oscillator at U3101 was not operating

properly

CTC177 U3201 The set had no Vertical deflection. The T Chip

had

CTC177 U3201 Vertical foldover at top and the bottom was pulled Pin 5 of IC4501 measured 18V and pin 16 of

Lifted JW322 and applied an external drive to

RN45

U1001 w

System Control

CTC177 C3109 Dead set. Replaced the eeprom twice and the

CTC177 U3201 On screen display is stretched and shifted to left.

25GC710

microprocessor once. Checking the clock and data lines at pins 15 & 16 of u3101 saw no activity. The oscillator was running on pins 41 & 42. Measured dc voltage at pins 5 & 6 of the micro, found pin 6 down to

Pin 6 of u3201 (data line) was compressed to

3.5vpp pulses lifting pin 6 restored to 5.1vpp.

Removing c3109 in the circuit off pin 6 of u3101

brought the voltage up to 4.7v and allowed the set

to turn on. Replace c3109.

Replacement of u3201 restored proper operation.27GT614

Page 71

Circuit Chassis Part Problem SolutionModel

System Control

CTC177 EEPROM PIP pix was missing. The EEPROM (U3201) had

been r

CTC177 VERT ADJ Intermittent Vertical foldover at the bottom one t Changing the Vertical Adjustments in the SVC

CTC177 connection Intermittently tv would go off than back on, but

CTC177 Q3101 Dead set The reset line on U3101 was 0V. Replacing a

25GT506

all customer controls (color, brightness, contrast & etc.) Are on the left end.

Checking the service mode parameters for PIP

(20,

Corrected bad solder connections on t4401 (ihvt)

pins 1 & 2.

leaky

System Control

CTC177 Q4105 Dead set U3101 pin 20 measured 2.5V and the reset pin 1

was

CTC177 U3201 Dead set. High voltage came up as soon as AC was aChecking voltage at the front panel inputs to

U310

Page 72

Circuit Chassis Part Problem SolutionModel

System Control

CTC177 U3101 PIN Dead set Pin 5 of U3101 measured 2.5 volts, should have

bee

CTC177 C3103 Volume down from front panel would make the

volume go up. With the remote the volume would work okay. The micro had been change by the servicer before he called. Pin 7 u3101 was at 2.2 vdc instead of 4.5 vdc. C3103 was pulling the pin low.

ctc177 U3201 Tv was stuck in the Spanish mode. There is not a

Spanish option in the menu.

CTC177AA U3201 Had no vert. U1001 had been replaced. Lifted

jw322 and drive rn4501 with a b&k analyzer to get sweep. Once he had sweep he could get the service menu. When he went to vert centering in the menu it was at 238 instead of a value between 00 and 15.

Replace c3103G2766SWK

Replaced u3201 and menus went back to English.G27613

Aligned Vertical centering25GT506

System Control

CTC177 U3201 Set powers on with ac applied. Pressing the power

CTC177AD C3310 Two narrow menus appear beside each other when

F25651BL

button caused the display to go off. The picture remains. Pressing the power button again caused the picture to go away, the degauss relay would energize. 3-4 seconds later, the picture would return.

called up. Tech noticed distorted signals at u3101 pins 17, 18 & 19. Under close inspection, c3310 off u3101-27 (vco) was found cracked.

Replacing the eeprom, u3201, restored normal

operation to the set.

Replacement of c3310 restored normal menus.

Page 73

Circuit Chassis Part Problem SolutionModel

System Control

CTC177 connection Tv wont turn on with power button on set, but

ctc177 u3201 Very slow channel change in cable mode, air ok.

CTC177 C3310 Menu is doubled. U3101 pins 17, 18 and 19 had distorted signals. C3

CTC177 Solder No autoprograming. U3101 pin 39 had no sync

G27343

will with remote. Otherwise tv worked.

The tv would take 3 seconds to find a channel when in cable mode. Agc at pin 12 of u1001 would wander high and low a couple of times before tv would lock on channel.

pulse. Found q3301 was not soldered at the collector. Resoldering q3301 returned autoprograming.

Removed solder splash near power switch s3411

on front panel assembly.

Changing u3201 repaired set.f27671se

Resoldered q3301.

System Control

CTC177 C3115 Dead set. will not turn on.the oscillator at u3101

was not operating normal.the signal at pin 41 was weak. found c3115 had changed value from 56pf down to 8pf.

ctc177ae U3101 Compressed osd characters. Replacing the eeprom

did not help.

Replacement of c3115.

Replaced defective u3101.25gc752

Page 74

Circuit Chassis Part Problem SolutionModel

System Control

ctc177bh2 trace No video or osd. The horizontal pulse to u3101

pin 26 ( chassis family 2 ) was missing. Found open trace from pin 8 of the ihvt to r3343 to the emitter of q3305.

CTC177 C3106 Unit would turn on if you hit the volume up button Change c3106.

CTC177 TRACE No control with remote. Remote would operate

other

CTC177 U2901 Tv had normal video, when you try to switch to

external video, you would still get tv video from the tuner. the tech first changed u3201, no improvement.then u2901 was replaced, no help. Finally he replaced u3201 again and the set was fixed.it appears tha

Repaired open trace.

Placed a jumper between r3301 & jw453 and

remote o

Replacement of u3201, u2901.

System Control

ctc177 u3201 Intermittent video. U2901 would loose all

voltages on all pins except 20,21,22 an b+ pins. The ic was changed. Video could be brought back by jumping out the chip. There was never any pip functions. Symptom could come and go at any time.

CTC177 Alignment Vertical is folded over at the top and stretched out

on the bottom. Servicer had already replaced u4501 and u1001. Pin 5 of u4501 was at 19 volts. Entered the service menu and found p05 at v00 (vertical dc). Ran the value up to v06 and vertical returned t

Replacing u3201 repaired the set.f25190se

Realign vertical settings in service menu. (have

fixed several TVs with this)

Page 75

Circuit Chassis Part Problem SolutionModel

System Control

CTC177 C3310 Osd rolling vertically. there were three sets of the

same osd display. they were displayed horizontally. checked waveforms at pins 24, 25 of u3101 and they were fine. found noise on pin 27, u3101, which is the vco pin.traced fault to an open c3310.

CTC177 alignment During chan change the consumer complained of a

very intermittent vertical foldover at the bottom 1/3 of the screen. You would probably not think anything about it because it happened so quick and blame it on no sync to the vertical just shortly after ch

ctc177bd r3203 Dead. Servicer found that he could turn set on if

he lifted jw 407 or jw408. With both jumpers in the unit the data lines were at 3v dc and constant data. Servicer noticed a brown dot on r3203 (off of pin 5 of u3201). We put a jumper across this resistor

ctc177aa3 paint Dead. Found that the dc level on pin 52 of u1001

was at 1.7v on pin 14 of u3101 it was 4.7v. Lifting components found that the trace between pin 52 of u1001 and the jumper jw443 was loading the line down. Starting at jw443 we started removing the black pa

Replacement of c3310.

Align vertical

Replaced r3203 repaired set.g27681ck

remove paint25gt506

System Control

CTC177BF JW408 Dead , servicer had replaced u3101 and u3201. On

u3201- 5, 6 there was 2.5vdc on each pin. Servicer was instructed to lift jw408 and jw470. When these were located servicer found a solder splash across these jumpers.

CTC177 Q3303 No closed caption. osd was normal found no video

at u3101-13 following from u1001-44 lost at q3304. Checking voltages we found q3304 turned off emitter was at 5v. Found q3303 at 11.8v at all three leads. Checking showed it to be shorted

Removed solder splash and set worked correctly

Replace q3303.F27631

Page 76

Circuit Chassis Part Problem SolutionModel

System Control

ctc177 c3126 No operation. Micro not running. Reset line low.

Base q3101 .6 v. Anode of cr3102 4.8 v cathode

4.1 volts. Found c3126 shorted.

CTC177FE R3132 Dead set no reset at u3101-1 . R3132 82k and

r3133 100k were open.

CTC177 U3101 White square comes up right of center, looks like

a computer cursor.

CTC177bh2 C3114 Set would not turn on u3101 had no clock found

c3114 was 2k to gnd

Replace c3126

Replaced r3132 and r3133F25671FE

Replace u3101F27252

Replaced c3114F27251wn

System Control

CTC177 U3201 Had vert fold over at top and the bottom was

pulled up 3 inches ic4501 had been replaced. Pin 5 of u4501 was at 18vdc and pin 16 u1001 was at

7.5vdc. Replaced u3201 and vertical worked properly.

CTC177 JC430 Brightness goes low. Speakers turned off.jc430 not

soldered

Replace u3201

Resoldered jc430 off u3201-8F27671SE

Page 77

Circuit Chassis Part Problem SolutionModel

System Control

ctc177 q3101 Dead set. Voltage at pin16 of ic 3101 is 0vdc. At

CTC177 SW3430 Dead unit. Checking the micro u3101 found pin 8

CTC177 U3101 No OSD. This is a new chassis where the OSD goes sReplace U3101.F25254

ctc177af3 q3101+310 Dead set. Found all voltages on u3101 to be ok.

25gt506

pin15 of ic 3101 4.8 vdc.. There is no data on pins 15 and 16 of u3101. Pin 1 of ic3101 is 0vdc...

at .3vdc. Unsoldering the menu switch sw3430 cleared the pin.

f25251wn

No data appeared when trying to turn on set. Osc running. Only clue was pin 2 of micro (reset) was at 5.2v instead of 5.4v. Wer momentarily ground pin 2 and then set would turn on and work The set went back

Found q3101 shorted c-e. Replaced transistor and

set worked normally.

Replace sw3430

Replaced the reset transistors q3101 and q3102

and set was repaired.

System Control

CTC177 U3201 Speaker mute is activated u3101-29 is high a

5vdc activating the speaker mute. This is caused by u3201.

CTC177bg U1001 Set was dead, with 5 volts on pin 5 of u3101.

27GC901

Found by lifting pin 51, 52, 53 of the u1001 tchip, pin 5 of u3101 would return to 0volts. Found that pin 53 measured 327ohms to vcc pin

22.

Replace u320125GT506

Replaced u1001, and normal operation was

restored.

Page 78

Circuit Chassis Part Problem SolutionModel

System Control

ctc177 u3201 Shaded bar in pix on channel 50 uhf only. Not all

have the bar on the same station. One was fixed by changing u7301. U7301 did not fix this set. When checking tuner parameters we found that we could run them up to 247.

CTC177 U3101 OSD piecrust. The set operated normally except

the

ctc177am r3104 Dead set unless power button is pressed

immediately after plug in. If power button is pressed in time, the vol up and down, and the channel up down will display menu... There is no control over the menu once it is up.. The unit can not be powered down eit

CTC177 C3103 Dead set. U3101 3201 had been replaced for

N\A

other reasons, after which the set was dead. No data or clock activity on u3101 pins 15 & 16 in the standby mode nor when trying to turn the set on. Oscillator was running correctly. Voltages were normal at pins

Changing u3201 cleared the symptom.f25650bc

U3101 pin 21 was internally shorted to pin 26.

Rep

Replaced def r3104g25361bk

We located a technician induced short across

c3103 off pin 7. Removing it restored normal

operation. The cap is right beside a system

control shield ground tab.

System Control

CTC177 U3201 Red colors look fuzzy, distorted and the greens

were smeary.

CTC177BD U3201 High voltage came up as soon as ac was applied.

G27687WK

The power button had no effect and no picture, sound or osd appeared. Checking voltage at the front panel inputs to u3101, found pin 5 always high with pins 6, 7 & 8 also high. No change of data activity w

Replacement of u3201.

Replacement of the eeprom, u3201, restored

normal operation to the set.

Page 79

Circuit Chassis Part Problem SolutionModel

System Control

ctc177bh u3101 Some channels would have excessive red in pix.

Other channels were fine.

CTC177BG IR Remote will operate at a short distance of a few

feet. Removing the ir window allowed the remote to operate at great distances.

CTC177BB SOLDER Set was dead with pin 5 of u3101 measuring 2.5

volts. Should of been zero. Found pin 21 of u3101 with a bad solder connection.

CTC177 R3120 Dead set. Found no reset voltage on pin 1 of

u3101. Traced problem to open resistor, r3120 off pin 1.

Problem was solved by replacing u3101.27gt613

Replacement of the ir window.G27341

Soldering pin 21 of u3101 restored pin 5 to zero

and set turned on.

Replace r3120

System Control

CTC177AD C3201 Dead set. Pin 5 of u3101 was at 4.5 volts. U3101

and u3201 had both been replaced. Voltages on pin 5 & 6 of u3201 were at 3 volts but pin 8 was close to zero.

ctc177am2 r3135 Intermittently set would turn on. Press again the

audio would turn off. When pressed again the video would disappear. Intermittently the set would go nuts when channel changed. U1001(52) there was 4.9v and sometimes 3.7v.u3101 (14) always had 4.9v. R3135

Found cap. C3201 was shorted. This cap. Was off

pin 8.

Replaced r3135 to repair set.g25342a

Page 80

Circuit Chassis Part Problem SolutionModel

System Control

CTC177 U7401 Dead set intermittently. Pix flashes intermittentl U3101 pins 5 and 6 measured 2.5V. U7401 pins 4

and

CTC177 R3203 Dead set. The set would turn on if JW407 or

JW408

CTC177 C3114, JC4 Dead set. U3101 pin 36 measured zero volts, pin 37 was at

ctc177 c3312 No remote. Pin 3 of u3101 at 2.5v dc. Replacement of leaky c3312 off of pin 3 of

25gt522

R3203 (off of pin 5 of U3201) was defective.

Repla

u3101 repaired set.

System Control

CTC177 R3135 Func cntrls inop. When buttons were pressed,

other

ctc177 N\A Menus were shown in triplicate kind of like 3

ghosts. Servicer found bad solder connection on c3310. C3310 is at u3101 pin 27.

Pin 52 of U1001 measured 4.9V to 3.7V at times.

Resoldered c331025gc722

Page 81

Circuit Chassis Part Problem SolutionModel

System Control

CTC177 R3322 OSD missing. The FSW signal was present on pin 18 of U1001,

but

CTC177 EEPROM No small picture in the pip mode. The eeprom,

u3201, had been replaced for no pip functions. After replacement of the eeprom, the small box appeared but with no picture in it. Checking parameters 20, 21, 22 & 23 they were all at 00.

CTC177AA3 Trace Dead and 0 volts on u3101-2 reset pin. Measuring

CTC177 U7401 Dead set intermittently or Pix flashes intermitten When the set was dead, there was approximately

25GT506

voltages we found q3102 was biased on because the base voltage was too low. We found 0 volts to r3132.

Adjusting the parameter values, especially

brightness and contrast, returned the pip picture

to normal.

Repaired open trace between jc403 & r3132.

Tech said there is a small spot of green corrosion

on the trace.

2.5

System Control

CTC177 Trace No on screen display- had h&v sync into u3101,

ctc177 U3101 Dead set. U3201 and u3101 would initialize

F25671

and osd signals were being generated at u310117,18,19. Checked fast switch line at u3101-22 and found a change from 0vdc with no display to .85vdc when a display key was pushed. Checked u1001-39 fast switch

properly. Clock and data looked good when the power button was pushed. U3201 and u1001 had been replaced. All the voltages around u1001, u3201, and u3101 looked good.

Found open trace between jw436 & r2733 in the

fast switch line between u3101-22 and u1001-39.

Repaired trace and osd was restored.

Replaced u3101 and the set worked.

Page 82

Circuit Chassis Part Problem SolutionModel

System Control

CTC177 Q3305 No osd. No signal at u3101-18 and only 1 volt p-

p at pin 22. The osd sync signals at u3101 pins 24 & 25 were ok. However, the dc voltage at pin 24 measured 3.8 volts.

ctc177 u3101 Channel 4 (osd) flashes on and off. Screen is dark.

Turning up screen will reveal something like a pix flashing on and off in the background.

CTC177 TRACE Dead set The DC level on pin 52 of U1001 was at 1.7V.

CTC177AM2 JW427 No menus when pressing the front panel button.

G27302AT

Both the vol up and vol down buttons on the fpa would increase volume.

Replaced q3305 with emitter to collector short.F25190

Replaced u3101 and set was repaired.25gt522

Removing a solder bridge from jw427 & jw428

resolved the problem. These jumpers go to vol up,

vol down & menu switches in the fpa circuit.

System Control

Tuning System

CTC177 r3134 Dead set, no power on.standby supply

normal.checking voltages at the cpu, found enable line to be the problem.voltage at pin 14, u3101 was 4 volts and the voltage at pin 52, u1001 was 0 volt. Found a solder splash at one of r3134 (connected to pin 14, u31

CTC177 R7403 Tuner inop There was no change in the DC bias to Q7401-C

Remove solder splash.

even

Page 83

Circuit Chassis Part Problem SolutionModel

Tuning System

CTC177 C7102 Channels above 50 snowy. The tuning,

bandswitching, & agc voltages were correct. On cr7101 the voltage was 0vdc, making a resistance measurement to ground there was a dead short. Lifting c7102 off the pads allowed the voltage to increase.

CTC177 COPPER T Cable tuning inop. There was no tuning of high or Resoldering a bad copper trace from the tuner IF o

CTC177ae CR7109 Would tune ch2 - ch6, rest ch7 - ch50 poor or

missing. Q7402 would switch form 12v to -.3volts due to cr7109 being shorted.

CTC177AC C7132 Snowy picture on channels above chan. 6.

F25190SE

Voltages at u7501 pins 7, 8 & 14 were normal. Checking the cathode voltage at cr7108, found it remained at .4vdc. Measuring resistance to ground at r7519 (rf primary circuit) to ground, we read 32k ohms on the side

Replacement of c7102 resolved the problem

Replaced cr7109, located in the tuner.

Found a shorted c7132 toward the uhf circuit.

Replacement of the cap restored normal picture.

Tuning System

CTC177 CR4303 Tuner inop. No low VHF tuning. There was zero volts on both ends of CR7303.

Repla

CTC177 C7134 Low VHF tuning missing. High VHF tuning was

normal

Checking the collector of Q7401 in the low band

Page 84

Circuit Chassis Part Problem SolutionModel

Tuning System

CTC177 R7413 Won't tune vhf channels. Uhf tunes normally.

The collector voltage at q7404 would not change between uhv & vhf.

CTC177 R7401 Snowy pix on channels 7 and up. Checking voltages at U7501 showed on pin 3 was

CTC177 C7410 Dead set U3201 had been replaced. Pin 5 of U3201 was at

CTC177 R7413 Set will not tune VHF channels. UHF channels are nThe collector voltage at Q7404 would not change

R7413 was open off the base q7404.

bel

zer

Tuning System

CTC177BB R7514 Poor tuning ch's 30- 50. All others good. At

u7501-14 we had 15v but at cr7108 we had .34v. R7514 at pin 14 checked good in circuit, but the 15v drop was across it. Bridging another 100k across r7514 restored normal voltage at cr7108 and normal tuning on

CTC177 C7132 Pix snowy in channels above channel 6. Voltages at U7501 pins 7, 8 and 14 were normal.

Replacement of r7514.G27687WK

Page 85

Circuit Chassis Part Problem SolutionModel

Tuning System

CTC177AK R7415 Weak tuning channels 7-13/ 18+...q7402-c stays

at -16v. U7401- 8 switches between +12v and 0v. R7415 between u7401-8 & q7402-b checked 10m ohms. Replaced open r7415 & restored normal tuning.

CTC177 R7401 Pix snowy when tuned to the upper channels in

each

CTC177 R7127 Tuner will not tune high VHF or UHF channels. Q7402 collector was switching between VHF low

CTC177 Q7401 Tuning inop. Set will only receive channel 2 until Putting cool spray on IC7401 caused unit to fail.

Replaced open r7415.25GC710

With channel 6 selected, the voltage was down to

and

Tuning System

CTC177 U7301 Channels missing. Cable channels 51 and above

were

CTC177 TRACE Pix snowy on some channels. Traced voltage to both sides of R7145 and found

U7301 was defective. Replacing U7301 repaired

the

Page 86

Circuit Chassis Part Problem SolutionModel

Tuning System

CTC177 R7408 UHF snow/VHF missing U7501 had between 30 and 33 volts on pins 8, 14,

CTC177 U7401 Will not tune low band vhf, channel 8, channel

14 will tune in when you select channel 19. isolated fault to u7401.

CTC177 U7301 Cable channels 51 and above not working. Replacement of u7301.

CTC177 C7408 Tuning inop U7401 pin 10 was at zero volts. Q4106 emitter

Replacement of u7401.

was

Tuning System

CTC177 C7110 Poor tuning, especially on channels 2- 6, 14- 17.

Q7402-c had 12v on 7- 13, 18-50, but 0v on 26,etc. Found that cr7112 had 0v on the anode at all times. Found c7110 shorted at the anode of cr7112. Replacing c7110 restored normal tuning.

CTC177 C7104 UHF poor. The VHF was normal. C7104 capacitor that goes to Q7101 was soldered

Replace shorted c7110.

Page 87

Circuit Chassis Part Problem SolutionModel

Tuning System

CTC177 Y7401 Tuner inop The tuning voltage was low. Checking the 4MHz

osci

ctc177af3 N\A Weak on all vhf stations. Found no voltages off

except agc high. Found through signal injection that the signal was lost between cathode of cr7112 and cathode of cr7105. Traced to break under c7137.

ctc177cc c7319 No cable below ch 51. Band switch ok. Found

u7301 pin 9 at 1.5v and pin 11 at .4v. R7305 had 12v and 0v on it. C7319 was shorted to ground. Removed the cap and the voltages and the tv returned to normal operation.

CTC177AC J3 No tuning. Voltages in pll circuit were normal, but

F25190SE

u7501 pins 7, 8 & 14 were at 30vdc on all channels. U7501 pin 3 was at 12vdc, and didn't change. Changed u7501 with the same result. Resistance to ground from pins 8 & 14 we found 68k. Should have been 2

Jumped broken trace to repair set.f25250bc

Replace c7319.31gt657

These resistors ground at j3 on the micro shield.

This tab connection was open. Repairing open

ground at j3 restored nor- voltages and tuning.

Tuning System

CTC177 Q7402 Tuner inop. The set had no high band VHF. The

low

CTC177 U7401 Tv would intermittently tune lower channels in

the same band while the ch. osd still showed the orig.channel number. It would also stay tuned to the same channel while trying to change channels (ch. osd would indicate that channels were changing). This w

Q7402 collector remained a negative voltage

while

Replacement of u7401 repaired tvG26683CK

Page 88

Circuit Chassis Part Problem SolutionModel

Tuning System

CTC177ae C7313 Uhf good, vhf snow. U7301 pin 2 was down to

.6vdc. Lifting c7313 the voltage came back.

CTC177CD Q7404 Vhf ch. Were snowy. Found q7404 shorted. Replace q7404

CTC177 R7514 Tuning inop channels 30 through 50 only. Measured 15V at U7501 pin 14, but 0.34V at

ctc177 cr7110 No vhf 7 to 13 or 22 up. Other channels ok.

Suspected band switching so we checked voltages on the switching diodes. Anode of cr7110 measured 12 volts. It should have measured .8 if diode was conducting. Diode checked open.

Replaced c7313.

CR7108.

Replaced diode. Restored operation.

Tuning System

CTC177 U7401 Pix flashes intermittently. Checking all the solder points around the tuner sh

ctc177BD q7401 Will only receive channel 2 when the unit is

cold...after the unit is warm all channels work fine. Putting cool spray on ic7401 will cause the unit to fail. Found q7401 bad base would open when cold.

Replace q7401G27681

Page 89

Circuit Chassis Part Problem SolutionModel

Tuning System

CTC177 C7319 Tuning inop below channel 51. Band switch checked normal. Measured pin 9 of

U730

CTC177 J3 Tuning inop Voltages in PLL circuit were normal. U7501 pin

CTC177 L2302 Tuning drifts. Channels 9 and 13 are slightly mist Replacing L2302 (off pin 62 of T-chip) repaired

CTC177 R7146 Vhf stations were snowy. Found zero volts on

q7102-g2 vhf rf amp.

Replaced open r7146.G25341

Tuning System

CTC177 R7304 Tuner inop. The set will not tune VHF channels. ThThere was no FLO signal at U7401 pin 11 with a

VHF

CTC177 Q7404 Very weak Snowy pix on channel 51 and up in the caQ7404 had 11.9V on the emitter, 10.6V on the

base

Page 90

Circuit Chassis Part Problem SolutionModel

Tuning System

CTC177 L2302 Chans 9 and 13 slightly mistuned and a slight buzz

CTC177 U7401 With tv on channels 2 thru 6, 98 & 99 received a

ctc177aa q7404 Very weak snowy pix on ch 51 and up in cable.

CTC177 WIRE Dead set int The white wire from E116 (near the tuner) to

F27671SE

in the audio in the background.

detuned channel 18. All other channels were snow. Tuning voltage (u7501-8) stayed at 27 volts.

Looked at q7404 and found 11.9v e, 10.6v b, and 5v c when tuned to ch 53. Jumped q7404 e to c and pix returned to normal.

Replacing l2302 cured the problem.(off pin 62 of

t chip)

Replaced u7401.GT506

Replace q7404.25gt506

E16 (

Tuning System

CTC177 C7506 Pix snowy on Hi-VHF and UHF channels. Low-

band VHF

CTC177 J3 The set intermittently Changes channels and

Tuner

U7301 and U7401 had been replaced. Checking

the vo

Repairing a bad solder connection at J3 (tuner shi

Page 91

Circuit Chassis Part Problem SolutionModel

Tuning System

CTC177 Y7401 Vhf lo channels appear in uhf band. The tuning

CTC177 C7404 No tuning tuning voltage on the collector of

CTC177 CR7303 Won't Tune channels 7 through 13. The collector of Q7402 switches from -14 volts

CTC177AE trace Snowy picture on vhf. Checking voltages found no

25GT506

voltage on the collector of q7401 was at +30 volts and would not change. Band switching logic at u7401 pins 9 and 8 was working (indicating ic was not dead). Checked oscillator on y7401 and found it to be ve

q7401 fixed at +30 volts. No oscillator voltage present on y7401. The glue used to fasten c7404 (off u7401 pin 2) had spread out and prevented one side of the capacitor from being soldered.

voltage to cr7111 & cr7113 (varactor diodes) cathodes.

Replaced y7401 and restored the oscillator

(typically around 1 vpp with a x10 probe) and

normal tuner operation.

Removed the excess glue and resoldered the c7404.25gt506

Repaired broken trace between r7511 and r7518.G26685WK

Tuning System

CTC177AA R7129 All channels above 6 are snowy. Bandswitch

ctc177 cr7303 Would not tune channels 7-13. The collector of

25GT506

voltages, good. Voltages at u7501 pin 8 and the cathode of cr7106, found u7501 had the correct voltage but cr7106 had 0v on the cathode all the time. Checking the circuit between u7501 and cr7106, found one end

q7402 switches from -14 volts in low band, to +12 volts in high band. The voltage at the anode of cr7303 also changed with the band switch, but the cathode always had zero volts on it.

Resoldering r7129 restored normal tuning on all

channels.

Replaced open cr7303.F25190se

Page 92

Circuit Chassis Part Problem SolutionModel

Tuning System

CTC177 CR7303 No low vhf. Zero volts on both ends of cr7303. Replaced shorted cr7303.

ctc177 r7408 Tuner tunes wrong channel. Ch2-6 gets ch18, 7-

13 gets 22. Found q7402 to be bad. It had 12ve and 0vb+c in all bands. Repaced no change. Q7401 c had the correct voltage On pin 3 of u7501 was wrong On ch 2 had 1.8v on q7401 while had 6v on pin 3 of u7

CTC177AE U7301 Some vhf channels were snowy.pin 1 on u7301

was low

ctc177aj2 c7144 No stations 7 and above. 2- 6 ok. Found the

collector of q7402 at 0v on ch 6 and 12v on ch 7. Found c7144 shorted. Lifting cap returned operation to normal.

Resoldering fixed the problem.g27341wk

Replaced u7301G26683

Replaced c7144.j25330bl

Tuning System

CTC177 R7305 No vhf, uhf ok-vhf pll voltage was 30v on all

channels. Checking u7301-11 we found less than 1v.in the b+ line to pin 11 we found that 12v was dropped across r7305 (620ohms). While soldering r7305, the tech noticed that the resistor was cracked. Subbing a

ctc177 r7306 Nothing but snow. Q7402 had 12vc on ch 7 and

.7vc on ch 6. Q7401 had 9vc ch 6 and 0vc ch7. Felt that q7401 probably wanted to go to 30v on ch 6 so we followed the line going to cr7302 and found that the voltage was dropping across each resistor till we go

Replacement of r7305.

Cleaned under r7306 to repair set.

Page 93

Circuit Chassis Part Problem SolutionModel

Tuning System

ctc177ac trace No tuner. Found pin 8 of u7401 stayed low in all

CTC177BG CR7305 Would not tune hi-vhf channels. Tthe collector of

CTC177 R7151 Snowy picture on vhf channels. Checking voltages

CTC177CC C7131 Poor cable tuning on channels 4 and above.

f25190se

bands. Q7402 has no 12v.

G27665WK

q7401 in hi-vhf, had 33v (tuning voltage).The vhf oscillator circuit at u7301 pins 9 & 11, there was no evidence of the oscillator running. Checking the varactors, cr7302 & cr7305 found insufficient solde

we found no voltage to cr7108 (varactor) cathode.

Channels 2- 6 useable, snowy picture on others. Found a leaky c7131.

Found open trace from fb4111 to 12v run c

source. Repair of trace fixed set.

Resoldering cr7305 restored normal hi-vhf tuning

operation.

Replaced open r7151.25GT506

Replaced c7131.31GT657

Tuning System

ctc177 c7102 Tunes only low vhf. Channels 7 and above are

snowy. Found that the dc voltage at the cathode of cr7107 was low, 1.6vdc. Back at u7501-8 voltage was 3.6 volts. Lifting r7101 allowed the high vhf channels to come in good. Resoldering r7101 and lifting c710

CTC177 U7501 Snowy picture. the voltages at u7501 were high

and not close to what they should be for various channels

Replaced leaky c7102.G27687wk

Replacement of u7501.

Page 94

Circuit Chassis Part Problem SolutionModel

Tuning System

CTC177 R7521 Audio weak. The set had only one weak channel. Q7501 (emitter) measured 21 volts instead of

1.06

CTC177 C7310 No tuning on any band, q7401-c at 0 volts.

Checking osc circuit, vhf tuning returned by lifting r7301. Checking cr7304-c, we found 9 volts, with r7301 lifted should be 0 volts. Lifting c7310 still gave 9 volts on cr7304-c. Removed glue from under c7310 an

CTC177 C7116 Snowy picture there was a lost of g2 voltage on

CTC177 R7116 Uhf was ok but vhf was snowy on low and high

F25190SE

q7102 transistor.

bands. The voltage on vhf rf. Amp. Q7102 was g1 10 volts, g2 was 7 volts and source was at 7 volts. The drain was ok at 11.5 volts.

Remove glue from under c7310 in tuner.

Had solder bridge under cap c7116. C7116 goes to

ground from g2 of q7102.

Found resistor r7116 a 68k off g1 of q7102 was

open.

Tuning System

CTC177 R7146 Vhf was snowy uhf was ok. Had 1.3 v on q7102

g2. The agc voltage from u1001-12 had 7v all the way to r7146. Had 1.3 on the other side of r7146. Resistor checked good 47 ohm and no shorts to ground. Replacing resistor cured prob. Perhaps we had leakage un

CTC177 R7313 Low band (2-6) was fine but 7-13 was not there.

We found that cr7303 was not getting any voltage in vfh high mode. Following back he saw that r7313 had been cracked when someone removed the tuner shield from bottom.

Replace r7146.F27351WN

Replace open r7313

Page 95

Circuit Chassis Part Problem SolutionModel

Tuning System

CTC177 C7116 Pix snowy There was a lot of G2 voltage on Q7102

transistor.

CTC177 FB4110 The set had intermittent short Vertical/Streaks in The feed through bead FB4110, which supplies the

CTC177BF R7401 Upper channels in each band are snowy. The

CTC177BE R7127 Wouldn't tune hi-vhf or uhf channels. Q7402

27GT617

lower channels in any band appear fairly normal. With channel 6 selected, at u7501 pin 3 the voltage was down to 1.1vdc. The collector voltage at q7401 was 5.5v.

F27351WN

collector was switching between vhf-low & high. On chan 13, checking the voltages at cr7109 and cr7110, cr7109 was normal with .8v on the anode and 0v on the cathode. Cr7110 anode near 10v and the cathode 9v.

Found r7401, 191k 1%, had increase to 2.3meg

ohms. Temporarily installing a 220k resistor in its

place produced a normal picture.

R7127 read open and a replacement restore solved

the problem.

Tuning System

CTC177CC R7304 Vhf both high and low were snowy uhf was okay

and u7301 had been replaced. Had proper band switching and uhf and vhf switching was ok. Voltages on u7301 measured ok except pin 11 which was less than 1vdc.

CTC177CD R7306 Cable channels 2-48 tuned poorly, 48+ tuned ok

F31671SE

checking tuning voltages at varactor diodes, found junction of cr7302 & cr7305 at .09vdc- checking r7307 and r7306, tech noticed that the end of r7306 connected to l7306 had never been soldered.

R7304 a 1k smd was not solder on one end.31GT657

Soldering loose end of r7306 restored normal

tuner operation.

Page 96

Circuit Chassis Part Problem SolutionModel

Tuning System

CTC177 R7315 No tuning. We had 16v at q7401-c on channel 2.

Removing the collector we still had 16c on the foil. Tracing out the foil we found a solder splash from one side of r7315 to the ground stake at g12. Set was a stock unit so splash must have been from factory

ctc177 glue Q7404+3 over heat and fail. Removed q7404+ 3, r7413, 14, and r7410,

CTC177 CR7305 No vhf high band channels. The tuning voltages

on u7501 checked ok. The band switching voltages were correct. The problem was isolated down to the cathode of cr7305. When the probe touched the cathode the vhf high band returned. Resoldering the diode took

CTC177 R7123 Tuner inop. The set had no VHF low or high band. R7123 (a 10 ohm SMD which goes to the (D) of

Remove solder splash.G26661CK

cleaned board of glue and replaced components.

Resoldered cr7305

Q7102

Tuning System

CTC177BF R7114 Poor tuning on most channels; ch 2 was good,

higher ch's were progressively worse-agc voltage was high on all channels. On ch 13, cr7106 in the single tuned circuit had 5.7v on the cathode, but cr7107 in the same circuit had 0v on the cathode. R7114 check

CTC177 C7102 Tuner inop. The tuner only tunes low VHF

channels.

Replace r7114.F27671SE

The DC voltage at the cathode of CR7107 was

low at

Page 97

Circuit Chassis Part Problem SolutionModel

Tuning System

CTC177 CBA Tuner inop Pin 8 of U7401 stayed low in all bands. Q7402

had

CTC177 R7121 Set had snowy vhf. Q7102 had 11 volts on the

source all the time. Found r7121 with a loose connection.

CTC177 R7146 Tuner inop. The VHF stations were snowy. There was zero volts on Q7102-G2 (VHF RF

CTC177 FB4110 Set had intermittent short vert. And streaking in

F25190SE

picture and intermittent snowy tuner.

Resolder r7121.

AMP). Rep

The feed thru bead fb4110 supplies the 33 volts to

the tuner. Had bad solder connection on one end.

Tuning System

CTC177 U7301 Set had intermittent tuning bending the board

CTC177AK Y7401 Poor tuning. Unit was are serviced for bad

F25190SE

picture would come in. When the picture went snowy the 12 volts disappeared from pin 8 of u7301.

25GC710

grounds around and under the tuner shield. Found the leads on the xtal were never clipped and they over extend the frame and touch the bottom cover. Shorting out the xtal.

Found bad connection from 12 volt run to smd

r7312.

Clip the leads on the y7401 and reinstall the

cover.

Page 98

Circuit Chassis Part Problem SolutionModel

Tuning System

CTC177AG R7401 Channels 7 and up tune but are snowy. Checking

voltages at u7501, we found on channel 7 that pin 3 was below 3vdc and should have been approx. 4v. At the collector of q7401 we read approx.

3.5v as called for.

CTC177 Q3301 Autoprogramming would not operate. Traced the sync signal to the base of the sync amp

CTC177 R7119 No vhf but uhf was ok. Q7102 the vhf rf amp had

zero volts on the g2. Found r7119 open.

CTC177 L7306 UHF/VHF inop Resoldering L7306 (off pin 11 of U7401) repaired

Found r7401, 191k 1% resistor open.25GT536

Replace R7119

Tuning System

CTC177 U7501 VHF/UHF inop The 33 volt supply to Q7401 and U7501-4

measured 5

CTC177 Q7102 Snowy vhf on lower and upper bands.uhf working

normal.

Replaced leaky rf amp q7102.

Page 99

Circuit Chassis Part Problem SolutionModel

Tuning System

CTC177 Q3301 No auto programming .Trace sync to base of

q3301 had no signal on collector.

CTC177 R7123 Had no vhf low or high band R7123 a 10 ohm smd which goes to the (d) of

CTC177AD L7306 No tuning vhf or uhf Resoldering l7306 (off pin 11 u7401) cured

ctc177 trace No tuner. Found no voltage at pin 10 of u7401.

G25341WK

f27351wn

Q4106 had 12v c, -9v b, and 0v e. Broke the trace between the base of q4106 and r4131. The negative voltage was on the resistors trace. Lifted the resistor and the voltage went to a -11.5v. Put the resistor

Q3301 was open. Had 3 sets with this problem.

q7102 the vhf rf amp. Was open.

problem.

Ran a jumper from the floating end to the base of

q4106 and the set worked normal.

Tuning System

CTC177 C7411 Tuning incorrect. The set would not tune cable cha C7411 on the clock line of U7401-5 was

defective.

CTC177 C7118 Very weak tuner all channels. C7118 off of drain of q7102 shorted putting 12v

Page 100

Circuit Chassis Part Problem SolutionModel

Tuning System

CTC177 C7144 Tuning inop above channel 6. The collector of Q7402 was at zero volts on

channe

CTC177 U7301 No uhf, vhf normal. u3201 had been changed

already. checking around pin 16, u7301 the pin measured 1.3 volts instead of the 2.8 volts as required.

CTC177 R7305 VHF missing. UHF was normal. VHF PLL voltage

was 3

CTC177 R7116 VHF snowy on low and high bands. UHF was

normal.

Replacement of u7301 restored uhf operation.

There was less than 1V on U7301 pin 11. R7305

was

The voltage on the VHF RF amplifier (Q7102)

was 10

Tuning System

ctc177 q7402 Channel 2-5 ok, 6 weak, rest missing. On q7401

CTC177 L7305 Set had no ch. 17. All other ch would come in.

25gt506

the tune volts were 1-2 volts higher than normal on channels 2-6. Other channels had 31 volts. Q7402 had 0 volts on its collector on all channels. Found 0 ohms to ground on q7402 collector. R7142 had one end

F27351

Could see ch.17 but there was lines like it was missed tune.

Repaired by removal of short and replacement of

open q7402

The servicer found spreading the winding of l7305

when the set was on 17 and the ch. came in good.

He then went back and check all the other ch. and

they were good.

Datasheet CTC 177 Datasheet

Specifications and Main Features

Frequently Asked Questions

User Manual