RCA CTC 177 Diagram

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.

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

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

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

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

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-

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.

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

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.

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

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

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.

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.

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.

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

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

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

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

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

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

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

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

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

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

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.

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

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

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

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

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.

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