Philips MG5.1E Schematic

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Colour Television

Chassis

MG5.1E


	Contents		Page



1		MG99 Light path	2
2		Introduction	8
3		Overall blockdiagram	9
4		Power supply	11
5		Scan circuits	24
6		Small signal panel	29
7		CRT drive circuit	69
8		Interface panel	72
9		SIDE JACK panel	74
10		Audio signal part	75
11		Digital convergence circuit	80

©Copyright reserved 1999 Philips Consumer Electronics B.V. Eindhoven, The Netherlands. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, or otherwise without the prior permission of Philips.

Published by LM 9972 Service PaCE	Printed in the Netherlands	Subject to modification	3122 785 10053

1. MG99 Light path

MG5.1E

1.MG99 Light path

MIRROR

R+G+B

RED

GREEN

BLUE

FRESNAL	LENTICULAR
LENS	SCREEN
	CL 96532100_078.eps
	121199

Figure 1-1

The MG99 Projection TV uses three single color tubes, Red, Green, and Blue. (Figure 1-1) The output of each tube is projected onto a mirror where it is then reflected onto a viewing screen. The Tubes are converged so the light from each tube strikes the same spot on the Fresnel Lens. The Fresnel Lens equalizes and concentrates the light to provide equal light uniformity across the screen. The Mirror is a first surface mirror type which has the reflective coating on the outside of the mirror. To prevent scratching of this surface, always use a soft cotton cloth to clean it.

Personal notes

MG5.1E	1. MG99 Light path	3

BLACK STRIPING

OUTPUT

LIGHT	CL 96532100_079.eps
	111199

Figure 1-2

The Lenticular Lens Screen calumniates the light from the Fresnel Lens. (Figure 1-2) The Lenticular Lens increases contrast by reducing the ambient light by the use of Black Striping. The Prismatic formation of the screen allows for nearly 3X light output as compared to a flat screen. Caution should be used when working with the screen. Damage can easily occur in the form of scratching, or by using certain chemical screen cleaners which can strip the black striping from the screen. To clean the screen, use one drop of dish washing detergent in a small bowl of water. (approximately 2 liters) Wipe the screen with a soft cotton cloth in the direction of the stripes.

Personal notes

4	1. MG99 Light path	MG5.1E

C ELEMENT LENS

CRT

		CL 96532100_080.eps



OUTPUT LENS	LIQUID COOLANT	111199

Figure 1-3

The Three CRT's are driven by 30KV of high voltage and 15KV of focus voltage. (Figure 1-3) The Tube produces a highly concentrated light output of color. A liquid coolant of Glycol is used to transfer heat from the face of the tube to the surrounding mechanical assembly. The

C-element lens seals the Coupling fluid within the coupler. The C-element lens and Coupling fluid are part of the light path and contribute to the properties of the optical system.

Personal notes

MG5.1E	1. MG99 Light path	5
	1.1 MG99 LIGHT PATH PROBLEMS

1.1MG99 LIGHT PATH PROBLEMS

CL 96532100_107.eps

021299

Figure 1-4

Look at the edges of the screen. They may be bowed inward.

PROBLEM - BOTTOM CORNERS DARK

PROBLEM - BOTTOM CORNERS COLORED

There is no problem with the set. The viewing angle is too high.

Personal notes

1. MG99 Light path

MG5.1E

1.1 MG99 LIGHT PATH PROBLEMS

CL 96532100_109.eps

151199

Figure 1-5

Fresnel may be reversed. Carefully remove the fresnel and point the grooves toward the viewer.

PROBLEM - BRIGTH AND DARK LINES ON A WHITE FIELD

Personal notes

MG5.1E

1. MG99 Light path

1.1 MG99 LIGHT PATH PROBLEMS

CL 96532100_110.eps

151199

Figure 1-6

The Fresnel offset is pointing down. The center of the Fresnel should be toward the top of the screen.

PROBLEMUPPER CORNERS OF THE SCREEN DARK

Personal notes

2. Introduction

MG5.1E

The2. 1999Introduction MG99 PTV chassis is designed for the European market. It is available in a 46 inch (117 cm) and a 55 inch (140 cm) 16 by 9 aspect ratio screen sizes. Selected Video can be displayed in either a 4 by 3, 14 by 9, or 16 by 9 aspect ratios. The set has a viewing angle of 160 degrees.

The MG99 PTV is capable of receiving signal from PAL B/G, PAL B/G 6OHz, PAL B/H, PAL D/K, PAL 1, PAL M, PAL N, PAL plus, SECAM B/G, SECAM D/K, SECAM L, AND SECAM Li TV systems. There are four composite video inputs which include three SCART connectors, and a Side Jack panel. The systems that can be applied to these inputs are NTSC 3.58, NTSC 4.43, NTSC Play Back, PAL 4.43, PAL, B/G Play Back, SECAM, and SECAM Play Back.

The set is equipped with a Frame and Line doubler to produce a horizontal resolution greater than 800 lines. The picture display is driven by three seven inch Red, Green, and Blue tubes.

The Sound system is driven by a 2 times 20 watt power amplifier. A switch in the rear of the set allows the sets internal speakers to be driven by an external amplifier.

The following sets will be sold in Europe: 46PP9501/05U.K. and Ireland 55PP9501/05U.K. and Ireland 46PP9501/12Western Europe 55PP9501/12Western Europe 46PP9501/58Eastern Europe 55PP9501/58Eastern Europe

These units will be distributed from Philips Bundling Center in Bruges, Belgium.

Personal notes

3. Overall blockdiagram

MG5.1E

3.Overall blockdiagram

SWITCH

PANEL

	Y_CVBS
SIDE JACK	C
PANEL	L	DELAY		SVM
	L			MODULE


	R
				BLUE
				CRT
MG99 SMALL
SIGNAL PANEL	Y
	Y
	R	CRT	R
		CRT		GREEN
	G	DRIVE	G	GREEN	RED
	G	DRIVE	G	CRT	RED
		CIRCUIT		CRT	CRT
	B	CIRCUIT	B		CRT
	B		B
	LEFT AUDIO
				AUDIO	SPEAKER
	RIGHT AUDIO			AMPLIFIER	SWITCH
	RIGHT AUDIO
					CONV R, G, B, FB
		INTENSITY
		CONTROL
CONV R, G, B, FB
LINE SYNC					CONVERGENCE
FRAME SYNC					PANEL
FRAME SYNC				LINE		CONV
				LINE		CONV
				DRIVE		YOKES
		INTERFACE PANEL
					LINE SYNC
					FRAME SYNC
	+5V STBY
	+15V STBY
	+130V
POWER	+38V			FRAME
SUPPLY	-38V			FRAME
	-38V			DRIVE
	+33V
	+15V
	-15V					FOCUS
	-7V7
	+8V6			HV
				HV
	+5V2			CIRCUIT	FOCUS/G2
					FOCUS/G2
					BLOCK	G2

HV/SCAN

PANEL

CL 96532100_081.eps 191199

Figure 3-1

3. Overall blockdiagram

MG5.1E

There are eleven PC boards in the MG99 chassis. (Figure 3-1) They are the Small Signal panel, Side Jack panel, Power Supply panel, Interface panel, SVM module, Blue CRT panel, Green CRT panel, Red CRT panel, High Voltage Scan panel, and Convergence panel.

Whenever AC power is applied to the set and the Mains switch is turned On, the Power Supply panel produces a 5 and a 15 volt standby supplies. When the set is turned On by the channel up button on the Front Keyboard or the Remote Control, the 130 volt, 38 volt, -38 volt, 33 volt, 15 volt, -15 volt, -7.7 volt, 8.6 volt, and 5.2 volt supplies are switched On.

Frame and Line drive from the Small Signal panel is routed through the Interface Panel to the Frame Drive and Line Drive circuits on the High voltage Scan panel. The High Voltage scan panel produces the High Voltage and Sync to the Convergence panel. Focus voltage from the High Voltage circuit is fed to a Focus/G2 block which provides Focus and G2 voltage to the three CRT'S. During the Convergence adjustment mode, Red, Green, Blue, and Fast Blanking from the Convergence Panel is fed to the Small Signal panel to generate the adjustment grid. The Small Signal panel selects video from the Antenna input, one of the three Scart connectors, or the Side Jack panel. The Small Signal panel outputs Red, Green, and Blue drive to the CRT drive circuit located on the Interface Panel. The CRT drive circuit then provides drive for the three CRT panels.

Left and Right channel audio from the Small Signal panel is routed through the Interface Panel to the Audio Amplifier panel. The Audio Amplifier panel has its own separate Switch Mode power supply. The output of the Audio Amplifier is then fed to the Speaker Switch panel which selects between the Audio Amplifier or External Audio from a separate amplifier.

Luminance or Y from the Small Signal panel is fed to a Delay circuit on the Interface panel before being applied to the SVM panel. The Scan Velocity Module speeds up the beam during light to dark transitions in the picture to provide a sharper image.

Personal notes

4. Power supply

MG5.1E

4.Power supply

		POWER		STBY	+5V STBY
AC	AC	POWER		STBY
AC	AC	FACTOR		POWER
INPUT	SWITCH	FACTOR		POWER
INPUT	SWITCH	CORRECTION		SUPPLY
CIRCUIT	PANEL	CORRECTION		SUPPLY
CIRCUIT	PANEL	CIRCUIT
		CIRCUIT
					+15V STBY
					+130V
				MAIN	+33V
				SMPS	+33V
				POWER	+35V
				SUPPLY	+35V
				SUPPLY
					-35V
	ON/OFF				+15V
					-15V
			+15V	5V2	+5V2
			+15V	REG
				REG

+15V	8V6	+8V6
+15V	REG
	REG


-15V	-7V7	-7V7
-15V	REG
	REG
		CL 96532100_082.eps
		121199

Figure 4-1

AC power is applied to the set on the Power Supply panel. (Figure 4-1) It is then fed to the Mains switch on the AC switch panel located on the front of the set. It is then fed back to the Power Supply panel and to the Power Factor Correction circuit. If the AC mains is 240 volts, the output of the Power Factor correction circuit is approximately 329 volts DC in standby and 350 volts DC when the set is turned On. The Power Factor correction circuit is turned Off during standby. This is a "HOT" chassis. When troubleshooting this or any power supply, always use an isolation transformer.

The Standby Power supply produces a 5 and a 15 volt supplies. It also provides operating voltage for the Power Factor Correction and the Audio Amplifier power supply. The Power Factor correction circuit is turned Off when the set is in the Standby mode.

The Main Switch Mode Power supply produces a 130 volt, a 33 volt, a 35 volt, a -35 volt, a 15 volt, and a

-15 volt supply. The Main SMPS and the Power Factor Correction Circuit is switched On by a Low from the Small Signal panel.

Personal notes

MG5.1E

4. Power supply

		TO AC SW BD
		1221
1000		1	4
5A		1	4
5A		5001
	2000	3011
	680n	3011
	680n
		3004		+5VSTBY
		3004
		3.3M		3007
				3007
			3005	6.8K
			3005	7000
			3.3M	7000
			3.3M	50_60HZ
				3008
			3006	10K
			470K	CL 96532100_083.eps
				CL 96532100_083.eps
				121199
		Figure 4-2

The applied AC voltage is fed to a 5 amp fuse and then to the Mains switch on the AC switch panel. (Figure 4-2) The AC voltage is fed to transistor 7000 and then to the Small Signal panel for clock synchronization.

The Standby Supply produces the 5 volt and 15 volt standby supplies. (Figure 4-3) The output of the Power Factor correction circuit PFCOUT is applied to Pin 5 of 7211 through Pins 2 and 4 of the switching transformer 5202. When the supply voltage is first applied, voltage through the internal startup resistor Rs is applied to capacitor 2283 via Pin 4. When the capacitor charges to 5.7 volts, the internal oscillator switches On driving the internal FET switch. When the voltage across capacitor 2283 drops below 4.7 volts, the IC turns Off. This cycle repeats until the 5 volt standby supply turns Shunt Regulator 6205 On. The supply voltage for the IC is then supplied to Pin 4 through 7213. Operating voltage to Pin 5 of 7213, the Audio Amplifier power supply, and the Power Factor correction circuit is supplied by Pin 5 of 5202. During normal operation, the 5 volt standby source is monitored by the Shunt Regulator 6205. If the 5 volt supply should increase, the Shut Regulator will cause more current to flow through the LED inside the opto-isolator 7213. This will reduce the resistance of the transistor inside 7213. As a result, more current will flow through the Sensing resistor inside 7211, which will reduce the On time of the FET inside the IC. This will reduce the output voltage to the correct level. This supply operates at approximately 100 KHz.

Personal notes

						+5VSTBY						5214
												5214
						3215							CONTROL
						3215					7204	5211
						1K	1			3241	7204	5211	5233
							1		5	6K8			PFC
													PFC


										3213		2209
										3213		100uF
							7206			10K		GND_C
							7206
				+5VSTBY			2		4
				3212	7205				GND_C
	3289	7214		10K
	10K	7214
	10K			3214
	ON_OFF			3214
	3288	2284		100K
	3288	2284
	10K	10n
						3216
				PFCOUT		10
				PFCOUT				5202			3230
										6235	3230
Figure						2228				6235	1K5
						2228		1	7		1K5
						100		1	7
						100
										2269	2211	6201
							GND_C	5		100	.1	8.2V			7208
4							GND_C	5		100					7208
3-				2206		6207		2	10		+15VSTBY		7209
				2206			6200			6204	+15VSTBY		RESET
				220uF			6200		9	6204	2270	3222		2210		RESET
					GND_C		6236				100uF	1K5		2210
					GND_C		6236	4	8		100uF	1K5	3240	22uF	3245
								4	8				3240	22uF	3245
		7211										6231	39K		1K	5234
					RS							6231				5234
					RS	5										+5VSTBY
						5										SOURCE
	4											2213				SOURCE
	4
					INTERNAL											2282
					INTERNAL				+5VSTBY			1000uF				2282
					SUPPLY				+5VSTBY							1uF
												2208				1uF
		5.7V	-								2226	2208
	5.7V	5.7V								3223		100
	5.7V	4.7V								3223		100
										47	22n
										47
									1		3244		3246		3247
				PWM			5		7213		3244	3239	3246		3247
		RS					5				33K	3239	2K4		180
											33K	2K4	2K4		180
												2K4
							4
	CL			1,2,3,7,8					2
	96532100			1,2,3,7,8			3287		2
				GND_C			470
				GND_C
										6205
011299	eps.084	2283								SHUT
		47uF								REGULATOR
				GND_C

1E.MG5

supply Power .4

4. Power supply

MG5.1E

To troubleshoot the Standby Supply, first check the supply voltage on Pin 5 of 7211. If there is no secondary voltage and 7211 is working correctly, startup pulses should be seen at Pin 5 of the IC. If the IC is pulsing and there is no secondary voltage, there is a problem with the outputs of 5202 or with the feedback circuit. If 7211 is not pulsing, either the IC or capacitor 2283 is defective.

When the set is turned On, transistor 7214 will turn Off turning 7205 On. This will turn the Optoisolator 7206 On turning transistor 7204 On, switching the operating voltage to the Power Factor Correction circuit. It also switches the operating voltage to the power supply on the Audio Amplifier panel on the line labeled "CONTROL".

Personal notes

MG5.1E			4. Power supply	15
			4.1 European power factor correction circuit

4.1	European	power factor correction circuit

AC IN

BRIDGE

CAP LOAD

AC CURRENT

CAPACITOR

CHARGE

VOLTAGE

A B	CL 96532100_085.eps
	121199

Figure 4-4

The input to most switching power supplies consists of a bridge rectifier and a large electrolytic capacitor. (Figure 4-4) When AC power is applied, the Capacitor will charge to approximately 1.4 times the RMS value of the applied AC voltage. This type of supply does not draw current from the AC power source through out the entire AC cycle. When the capacitor charge falls to point "A", the instantaneous value of the AC voltage exceeds the charge of the capacitor. The bridge diodes are then forward biased, causing current to flow from the AC source. Current will continue to flow from the AC line until the AC sinusoidal voltage reaches its peak at Point "B". At this point, the charge on the capacitor will exceed the AC line voltage reversing the bridge diodes. This results in an AC current waveform that is narrow and distorted compared to the AC voltage waveform. Non sinusoidal waveforms have a high harmonic content, with excessive peaks which results in a low power factor of 0.5 to 0.6. Power Factor is a ratio of real power divided by apparent power. Excessive harmonics and peak currents reduce the efficiency of the power distribution system.

The MG5.1 Projection TV without Power Factor correction has a high harmonic content of 85 percent, creating a Power Factor of 0.5. Current spikes of 7 amps will also be created in the AC supply. With the Power Factor correction circuit, the peak current is limited to 1.58 amps, with the harmonic content being reduced to 4.5 percent. The Power Factor is increased to 0.99. The ideal Power Factor is one, which occurs when the current is sinusoidal and in phase with the voltage. The European standard IEC1000 limits the current harmonic content of equipment supplied by the AC Mains.

Personal notes

4. Power supply

MG5.1E

4.1 European power factor correction circuit

		5109		6103
				6103
AC INPUT	BRIDGE	5	3	350V DC OUT
		5	3
				2110
	CURRENT SENSE	REGULATOR		7104
		DRIVE		7104
		7102
				CL 96532100_086.eps
				121199
		Figure 4-5

The MG5.1 Power Factor correction circuit uses a Boost regulator to smooth out the current draw from the AC line improving the Power Factor to 0.99, which is accomplished by drawing current from the AC source throughout the entire AC cycle making the current waveform sinusoidal. (figure 4-5) Input to the module is connected to the AC Mains. The output supplies are approximately 350 volts DC to the Main and Standby Switched mode Power Supply circuit. The Boost Regulator circuit produces a higher output voltage than the input voltage. The regulator drive circuit compares 6103's output voltage, the input voltage from the bridge, and the voltage across the current sensing resistors to control the On time of 7104. This will maintain the output voltage at 350 volts DC and limit the input current to acceptable levels. When 7104 is On, current flow through 5109 stores energy in the choke. When 7104 turns Off, 5109 reverses polarity and charges 2110. Using this type of regulation, current is drawn from the AC source throughout the entire cycle, keeping the current waveform sinusoidal. When the AC cycle is at its low point, 7104 is on for a longer period of time. When the AC voltage is at its peak, 7104 is on for a shorter time to store the same amount of energy in 5109 to maintain the output voltage at 350 volts.

If the Boost regulator circuit should become inoperative, due to a loss of regulator drive, operating voltage is still applied to the set. The supply voltage to the switching supplies will drop from 350 volt to approximately 329 volts depending on the Mains voltage. Since the customer would not detect a failure, the operation of this circuit should be checked after any repair of the set.

																						correction factor power Full 2.4	1E.MG5
																						circuit
				5006
				5003		3010													2105	3105
1222-1						2R2													470p	6R8
1222-1
		5005													5109
															5109			5105	6103		5103	5106
FROM AC														5	3			5105	6103		5103	5106
FROM AC								6000						5	3							PFCOUT
SW BOARD								6000														PFCOUT
				5004										15	13					2110	2107	350V DC OUT
										STARTUP VOLTAGE										2110		(329V)
										STARTUP VOLTAGE							5107			470uF		(329V)
1222-4										FOR FULL							5107			470uF	1n
				5007						POWER SECTION										GND_B
				5007
																						GND_C
							0.36V MAX											7104				GND_B
							0.36V MAX											7104
		3130		3131	3132	3133										3117				2120
		0R1		0R1	0R1	0R1										3117				220p
		0R1		0R1	0R1	0R1										10K				220p
	GND_HA															10K		GND_B
	GND_HA																	GND_B
			GND_B											PFC			GND_B
				R491
				330K
						R490										2113
	R493	C486		C485		1M										100uF		3115
	33K	.22		.22												GND_B		47
																GND_B							.4
						3111			3121		2114
		INST LINE VOLTAGE				1M			3121		2114
						1M			33K		1n5			19V
									33K		1n5												Power
																		5108
														(25V)				5108
									17		18	16	19
Figure														VCC
		4		7102
		4
										OSCILLATOR								3114		6104
																		47
	1.5-5.5V	7															OUTPUT
6-4	1.5-5.5V	7															OUTPUT						supply
														S	Q			20
														S	Q
	5.11V	6		GILBERTS				+			+		LOGIC	LATCH
				GILBERTS										LATCH
				MULTIPLIER										R
				MULTIPLIER							-
											-
								-										15
																+		15
										COMPARATOR						+
								CURRENT		COMPARATOR
								CURRENT									1.28
								AMPLIFIER								-	1.28
		+	-								IPK		V REF			OVP
											IPK		V REF			OVP
		5.11V
														5.11 V
		14	5.11V	13	5.45V	8	9	3127	5	5.45V	2	0.23V	11		3	4.3V			3108	3134
								18K											3108	3134
								18K											3M3	470K
			3124		2115														3M3	470K
			3124		2115
			330K		.33			3128	2116			3120
								3128	2n2			3120
								1K8	2n2			5K6				3109		3110
								1K8				5K6				3109		3110
								GND_B								47K		39K			3119
																					3119
																					3M3
																	GND_B	GND_B			3M3
	CL																GND_B	GND_B
	CL
	96532100						3123				3118		2118								3126
							1K8				3118		1uF
							1K8				390		1uF
											390										47K
																					47K
																				3125
	_																			1K
191199	eps.087																				GND_B
																							17

18	4. Power supply	MG5.1E
	4.2 Full power factor correction circuit

An explanation of the full Power Factor Correction circuit is now given. (Figure 4-6) The Power Factor Correction circuit is a fixed-frequency Pulse-Width modulated boost regulator power supply. Operating frequency is approximately 60 kilohertz. Due to the low power consumption of the set during the standby mode, the Power Factor Correction circuit is turned Off. The operating voltage, PFC, on Pin 19 of 7102 is turned Off. When the set is turned On, the operating voltage is switched to Pin 19 of 7102. Once the circuit is in operation, a 5.11 volt internal reference voltage on Pin 11 is applied to Pin 6 of the IC. Output of the bridge rectifier is fed to the IC on Pins 4 and 7. Feedback from the output circuit is fed to Pin 14 where it is multiplied with the Bridge output. Inputs to the Gilberts Multiplier produce an error signal that is fed to the current amplifier. The Gilberts Multiplier multiplies the bridge output voltage with the output voltage on D438. The 5.11 volt reference is used to provide a clamping reference for the other inputs. Input current is sampled by resistors 3130, 3131, 3132, and 3133. This sample is added to the error signal from the Multiplier going into Pin 8. The error signal is amplified and then compared to the oscillator ramp to determine the reset point for the latch. When the oscillator goes low, the latch is set making output "Q" High. With the other inputs to the AND gate High, Pin 20 then goes High, turning 7104 On. By comparing the input and output voltage, the On time of 7104 is increased when the AC voltage is at its low point to maintain the 350 volt DC output. When the AC input voltage is at its peak, 7104 is On for a shorter period.

The IPK circuit connected to Pin 2 is an overcurrent protection circuit which resets the latch if there is excessive current through the return resistors. This will reduce the On time of 7104. In a like manner, the OVP, Over Voltage Protection, circuit will reset the latch removing drive to Pin 20 is the output voltage exceeds 392 volts.

To check the operation of this circuit when the set is operating correctly, check the PFCOUT voltage. This voltage should be approximately 350 volts. If the output voltage is approximately 329 volts, this circuit is not working. Check the operating voltage on Pin 19 of 7102. Then check the output drive on Pin 20 and at the gate of 7104. There are three grounds on the Hot side of the supply. Ground HA is connected directly to the bridge 6000. Ground "B" is the ground for the Power Factor Correction circuit. If the current sensing resistors 3130 through 3133 should open, this would remove the ground for all the switching supplies and make the set inoperative. Ground "C" is the ground for the switching supplies. When ground "B" passes through the choke 5106, it becomes ground "C".

Startup up voltage for the Full Power supply is taken from the neutral side of the AC mains.

Personal notes

																														supply power Full 3.4	1E.MG5
																										3330	3331
																							2312			22K	22K
																							470P						+33V
																			4	14					5304	5305
															PFOUT				4	14									+130V
															PFOUT														+130V
																					2350		6305			2313		2314
																			6		470P					470uF		22uF
								3446												12		6315		3346
								10												12			3345
								10															3345
							3321												8				470R	470R
																			8

							8K2
						3320														15	5306	6306			5307
						3320																						+35V
						8K2
													3307
																				16

							6			2			33R												2316	2317		2318
					GND-C		6			2			33R												2316	2317		2318
					GND-C															17		2315			1000u	1000u		100n
																				17		2315			1000u	1000u		100n
													5302	6304	7301					18		470p
												3								18
																					5308	6307
		8				OVERVOLTAGE														19
		8	DEMAG		VCC	OVERVOLTAGE						4	3306		3305					19								-35V
					VCC	17V				A																		-35V
						17V				A
								S					10R		10K										2321	2321		2322
								S	Q	+		7		GND_C								2319			1000uF	1000u		100n
								FLIP		+
								FLIP		B	1V	2307	3310
		VCC						FLOP		B	1V	2307	3310	6302		3308	3309					470p									.4
								FLOP		-			330R	6302		3308	3309								1302
								R					330R			0R1	0R47					6309		5313	1302			5314
												2308		6303		0R1			10	20					4A
												2308		6303					10	20					4A				-15V
	2346		UNDER										2311		GND_C				11										-15V		Power
	2346					SOFT							1N			GND_C
	100N					SOFT							1N					GND_C		21
	100N	1	VOLTAGE			START																				2330		2331	2332
		1	VOLTAGE			START																				2330		2331	2332
Figure			LOCKOUT									13										2319				470u		100n	100n
			9.4/14.5																	22		2319				470u		100n	100n
			9.4/14.5																			470p
																						470p
								7302					3317					3447							1301	2325
		18V					VCC	7302		FB		5	15K					2.7K				6308		5310	4A	100n		5312
		18V										5	15K
																														+15V
																		GND_C												+15V
																		GND_C

7-4			REFERENCE							-		14														2324			2327	2326	supply
						OSCILLATOR		STANDBY		-												2323				2m2			470u	100n
										C																2m2			470u	100n
			SECTION							C
			SECTION							+												470p
										+												470p
														3315														5312
										2.5V				15K														5312
										2.5V
			16	15	11	10	9	12					3319													3328		3329
			16	15	11	10	9	12					15K										VCC			3328		330R
													GND_C										VCC			100R
		3313			2443	2442							GND_C		3316
		3313			2443	2442						3318			3316								5		1
		10K			1uF	1N		GND_C				3318			1K								5		1
							SYNC					150K			GND_C			2302						7303		3326		2328
							FROM			VCC								2302								3326		1u
							FROM			VCC																4K7		1u
							STBY																			4K7
							STBY
																		6301					4		2
																							4		2
										2303									STARTUP						3327
										100uF								3300							3327	3325			+130V
													3461					3300							100R	3325
										GND_C			3461					22K							100R	10K
													27K
																									2333	2334			3324
																									2333	2334			150K
	CL																	+5VSTBY						7303					3323
	eps.088 96532100																	+5VSTBY											2K7
															1305			7300	3304										3322
													+5VSTBY						1K		7309			3344					3322
													+5VSTBY						1K		7309			3344					470R
																								10K					130V
011299																			3303						ON_OFF				ADJ
																			100K				3343
																							3343	2349
															6313								10K	2349

																															19

20	4. Power supply	MG5.1E
	4.3 Full power supply

When the set is turned On, the Main Switch Mode power supply is turned On. (Figure 4-7) This supply produces the +130 volt, +33 volt, +35 volt, -35 volt, -15 volt, and +15 volt supplies.

When the On/Off line goes Low, transistor 7309 is turned Off, turning transistor 7300 On. This switches relay 1305 On. Startup voltage from the neutral side of the AC mains will charge capacitor 2303 to 14.5 volts which will overcome the undervoltage lockout of IC 7302. After the Soft Start capacitor 2443 charges, the oscillator inside the IC will turn On. Each cycle of the oscillator will set the flip-flop which will cause Pin 3 to go High. This will turn the FET switch 7301 On. Voltage is applied to the Drain of 7301 through Pins 4 and 8 of 5300 from the Power Factor Correction circuit. Current through sensing resistors 3308 and 3309 will develop a voltage which is applied to comparator "B" connected to Pin 7. When the voltage on Pin 7 reaches the reference voltage on the inverting input, the FlipFlop will be reset. The voltage on the inverting side of comparator "B" is limited to 1 volt. Therefore, the ramp voltage on Pin 7 will not exceed 1 volt. The circuit will continue to operate until the charge on capacitor 2303 falls below 9.4 volts shutting the IC Off. Each time 7301 is turned On, energy is stored in transformer 5300. Voltage from the Hot secondary on Pin 10 is rectified by 6301. When the output of this circuit has sufficient energy to maintain 2303 above 9.4 volts, the IC then operates in steady state.

When IC 7302 develops a normal steady state operation, the 130 volt supply is sampled by resistors 3324, 3323, and 3322. This sample voltage is then sent to Shunt regulator 7303 which drives the feedback optoisolator 7303. The feedback voltage on Pin 14 is then compared with an internal 2.5 volt reference by comparator "C". Comparator "C" then sets the reference voltage on the inverting side of comparator "B" to control the On time of the drive at Pin 3. If the voltage on Pin 14 increases due to the 130 volt supply increasing, the On time of the pulse on Pin 3 will be reduced. If the 130 volt supply decreases, the voltage on Pln 14 would decrease, causing the On time of the pulse on Pin 3 to increase. This is used to keep the 130 volt supply at the correct voltage. Variable resistor 3322 is used to adjust the 130 volt supply to the correct level.

The overvoltage protection circuit of the IC will shut the IC down if the VCC level on Pin 1 exceeds 17 volts.

To troubleshoot this circuit, first check the On/Off line from the Small Signal Panel to ensure that it is going Low. Then check for the presence of startup voltage on Pin 1 of the regulator IC 7302. If the IC is working correctly, this voltage will be changing from 9.4 to 14.5 volts. If the startup voltage is not present, check the startup resistor 3300 and the bridge rectifier. If the voltage on Pin 1 is changing, check the drive signal on Pin3. Then check for signal on the gate and drain of 7301. An excessive load on the secondary, a short on the 130 volt line for example, would cause the supply to pulse with little or no voltage on the secondary.

Personal notes

MG5.1E

4. Power supply

TO INTERFACE PANEL


1150/60HZ

10STBYRTN

+5VSTBY	9

-7V7	8

SSGND	7
SSGND	6
5V	5
+8V6	4
+15V	3
130VRTN	2
+130V	1

	TO AUDIO AMPLIFIER								TO	CONVERGENCE PANEL									TO SCAN	HIGH VOLTAGE PANEL					CL 96532100 052.eps 191199
		160V RTN	CONTROL													+15V RTN	+5V STBY	STBY RTN					+130V RTN	+130V RTN

160V DC	NC				+15V	-35V	-35V	RTN	RTN	+35V	+35V	-15V	15V RTN	+15V	+15V				ON/OFF	NC	+130V	+130V
1	2	3	4	1		2	3	4	5	6	7	8	9	10	6	5	4	3	2	1	4	3	2	1

		1203								1276								1212					1205

1202	POWER SUPPLY PANEL

1222

1221

1220

				1210
1	2	3	4	5	6	7	8	9
SS GND	SS GND	+5V2	+5V2	5V STBY	+8V6	+33V	ON/OFF	+15V
			TO	MG99 SMALL SIGNAL PANEL

AC SW BOARD

Figure 4-8

22	4. Power supply	MG5.1E
	4.3 Full power supply

The Power Factor Correction, Standby, and Full Power circuits are all located on the Power Supply panel. (Figure 4-8) The Standby supply feeds the 5 volt standby supply to the Small Signal panel via Pin 5 of connector 121 0. The Standby voltage is present whenever power is applied to the set and the Mains switch is On. The On/Off Command from the Small Signal panel is fed to the Power Supply on Pin 8 of connector 121 0. This Pin will measure 5 volts when the set is in the standby mode and 0 volts when the set is turned On. The +33, +15, +8.6, and +5.2 volt supplies to the Small Signal panel are developed after the set is turned On.

The +130, +15, +8.6, -7.7, and 5 volt standby voltages are fed to the Interface panel on connector 1202. The 50/60 Hz signal is a sync signal from the AC power mains which is used to provide sync to the clock circuit on the Small Signal panel. 350 volts from the Power Factor Correction circuit is fed to the Audio Amplifier on connector 1203. The Control line on Pin 4 of 1203 provides the operating voltage for the switching power supply on the Audio Amplifier panel. This Control voltage is switched Off when the set is in the Standby mode.

Connector 1276 routes power to the Convergence panel while connectors 1212 and 1211 feeds power to the Scan High Voltage panel.

Personal notes

MG5.1E

4. Power supply

4.3 Full power supply

		5109		6103
				6103
AC INPUT	BRIDGE	5	3	350V DC OUT
		5	3
				2110
	CURRENT SENSE	REGULATOR		7104
		DRIVE		7104
		7102
				CL 96532100_086.eps
				121199
		Figure 4-9

The +15 volt source is fed to transistor 7308. (Figure 4-9) This is a Buck Switch regulator circuit which produces the 5.2 volt source. Transistor 7308 is turned On and Off by the Switching regulator IC 7307. To maintain the 5.2 volt source at the correct voltage, the output is sampled and fed to Pin 5 of the IC. The voltage on Pin 5 is then compared with an internal reference. This drives the Pulse Width Modulator which controls the On time of 7308.

The -15 volt source is fed to linear regulator 7305 to produce the -7.7 volt source. The +15 volt source is also fed to the 8.6 volt regulator 7306 to develop the 8.6 volt source.

Personal notes

																										.5	24
																								5801		.CIRCUITS5 SCAN
																						10		5801	2825	1Line
																										1Line
																										Drive

																			FIL						470p
																	+240V		FIL			9			470p	3818
																	+240V				3865

													+130V									8		12	6802	1R
													+130V				2815				0R47	7		12	6802	+13V
																	2815									+13V
																	680p									2827
																	680p							13	2824	2827
													2816	3828				3815						13	2824	1000u
													2816	3828												1000u
													68K	68K												3819
													68K	68K			6801	0R27				6			470p	3819
																	6801	0R27				6		14	470p	1R
																								14		-13V
																						5			6803	-13V
													3825			2814				+130V		5			6803	2826
													3825			2814				+130V						2826
													68K			68u									2850	1000u
													3823									3			470p
									+130V				3823									3			3867
									+130V				68K												1R
													68K											15
												2809									A			15		+28V
																					A					+28V
																						1		16	6850
												100n										1		16	6850
												100n														2851
								2810	3810	3811																2851
								2810	3810	3811		2898														100u
								330u	2K2	2K2		2898
									2806			220U					2899
							2807		2806				7802				4n7
							100n		1n				7802
							100n		1n	1	4
									3808	1	4								2817			3821		2818	2822	RED	.5
									2K2						2811				2817			3821		2818	2822	YOKE
							3807		2K2	2	3	3813	3814		2811		6806		3n3			470R		820p	430n	YOKE
				3829	7803		330R					1R	3814		330p		6806										CIRCUITS SCAN
				3829	7803		330R			5800		1R	33R		330p
				15R						5800			33R
	1509-1			15R			3830	3809		7801			5805						2819					5804	2834
	1509-1																		2819						2834
		HDRV															6808		27n						430n	GREEN
1-5 Figure		HDRV					470R	330R									6808		27n						430n	GREEN
	LINE																									YOKE
	DRIVE						+15V																	5803
							+15V
																									2805
																		3681							2805
						+28V												3681						3452	100n	BLUE
								2801										2K2						3452		YOKE
																		2K2						4R7	3805	YOKE
																								4R7
							3803	100n					+15V			2573
							3803	100n					+15V		3590	2573									100R
							100R								3590	2n2						2452	2u2	3453
				2800						3840					100K	2n2								3453
				2800						3840			3457		100K									4R7
				1u		7800				1M			2K2							7552
						7800						E_W	7553											3454
								3801	3866	3802		E_W	7553											3454
								3801	3866									7551						4R7
			1507-4					27K	18K									7551						4R7
			1507-4					27K	18K	68K				3571	3591
			H_PUL							68K
			H_PUL		3890
					3890		3800						3458	2K2	2K2			3456						3455
			1511-1		100R		1K5						3458					100R						4R7
													2K2											4R7
													2K2
			HFB				3817																	2820
							3817															A		2820
							470R															A		4u7
							470R													3834				4u7
			1509-7																	3834
			1509-7						HPUL				3835							1R
			FBSO		+15V				HPUL											1R
			FBSO
													3K3
													3K3
													2837			6830				2836
				3833		3832							2837							1n
				100R		3K3							10u		2839			3839		5802
				100R		3K3						3836
			HPUL_BLNK										3812
		CL	HPUL_BLNK										3812		10n			330K		8	4
		CL										270R	100K							8	4
		96532100			7804							270R	100K
					7804		3831				+28V							7830			1
							3831				+28V										1
							68K						3837							6
							68K					2804			2838					6
												2804			2838
												10u	12K		1n							LV
	121199	eps.089																				LV
																					3806
																					1K
																											1E.MG5

MG5.1E	5. SCAN CIRCUITS	25
	5.1 Line Drive

Line Drive from the Small Signal panel is fed to connector 1509 Pin 1 and then to buffer transistor 7803. (Figure 5-1) Transistor 7803 then drives the Line driver transistor 7801. Line drive is then fed to the Line output transistor 7802. Transistor 7802 drives the three Line Yokes and the Scan transformer 5801. The Scan transformer produces a 240 volt supply for the CRT drive circuits, a Filament drive for the CRT'S, a plus and minus 13 volt supply for the Frame drive circuit. It also produces a 28 volt supply for the beam limiter circuit in the High Voltage circuit. The output of the Line Output transistor 7802 is also fed to buffer transistors 7800 and 7804 to produce a Line Sync pulse (HPUL) and Line feedback pulses to the Small Signal panel (H- PUL and HFB). The output of transistor 7804 also produces a Line Blanking pulse (HPUL-BLNK).

Drive for geometry correction from the Small Signal panel on the E-W line drives transistors 7553, 7551, and 7552. This circuit drives the return side of the Line Yokes to provide Horizontal corrections to the geometry. Geometry correction drive, E-W, is also fed to transistor 7830 which produces drive for the Dynamic Focus, LV. The Line component to the Dynamic Focus is added in transformer 5802.

The Line Sync (HPUL) is used to synchronize the High Voltage drive. If this pulse is missing, the High Voltage circuit will shut down. A loss of drive to the Line Yokes will cause the High Voltage to shut down.

Personal notes

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