PE0702A, V28A000962A1 (5V Yes, 12V/24V NO)

[yotsuya]

TV: Toshiba 46XV645U
PSU: PE0702A, V28A000962A1 (purchased used, appeared to been have been previously repaired and lasted 2 years)

Issues & History:

- No Power, No Click, No 5V: Tested and found Fuse R851 Open. Replaced R851 and Voltage regulator Q880. A well documented problem and it did bring back some life back to the board because after plugging, the relay engaged and I got 5V but still no 12 or 24V. No red light, nothing happens when power button is pressed.

- Confused, I obtained a repair kit which replaced a bunch of components. I also replaced the capacitors at c820, c821 as they seemed slightly bulged. End Result: No Difference - same issue.

Current State: I get 5V. I hear the relay engage. I do not get 12v. I do not get 24V. I do not see a red light. I press power button and nothing happens.

Pictures provided

Ideas? Where have I failed?

[dick_barton]

Re: PE0702A, V28A000962A1 (5V Yes, 12V/24V NO)

What voltage do you have on power on pin (P_On, Power ON/OFF) when you come out of standby?

https://www.youtube.com/watch?v=ttrSsgkI5TE

[yotsuya]

Re: PE0702A, V28A000962A1 (5V Yes, 12V/24V NO)

What voltage do you have on power on pin (P_On, Power ON/OFF) when you come out of standby?

https://www.youtube.com/watch?v=ttrSsgkI5TE

The Voltage I get 3.04V on POW_PRT and 5.5V on POW_SIG , Nothing on POW_TV, 15V AC_DET

[dick_barton]

Re: PE0702A, V28A000962A1 (5V Yes, 12V/24V NO)

So you have the following:-

Pow_Prt 3.04V
Pow_Sig 5.5V
Pow_TV 0.0V
AC_Det 15.0V

I'm not 100% certain but it looks as though Pow_Prot may be holding the power supply off and not giving the Pow_TV voltage out.

With the TV powered up what voltage do you have across the two pins of the large capacitors C821 and the one along side it.

If you disconnect the power supply from the mainboard and switch on what voltages do you have at the output pins of the power supply.

Have you searched for a schematic for the power supply which would be helpfull.

[vinceroger69]

Re: PE0702A, V28A000962A1 (5V Yes, 12V/24V NO)

the voltage chart provided in this thread post 23 may help
https://www.badcaps.net/forum/showth...PE0702A&page=2

[dick_barton]

Re: PE0702A, V28A000962A1 (5V Yes, 12V/24V NO)

That's interesting in that he cured his problem by reflashing the EEprom.

If you could provide a similar table as shown in the link above may prove to be usefull.

Good find VinceRoger69

[budm]

Re: PE0702A, V28A000962A1 (5V Yes, 12V/24V NO)

The Voltage I get 3.04V on POW_PRT and 5.5V on POW_SIG , Nothing on POW_TV, 15V AC_DET

https://www.badcaps.net/forum/attach...7&d=1465699555

You should do the same chart.
BTW, there must be error on testing, no way you can have 15V on the AC_DET.
All the measurement are done with meter set to DCV mode. 5.5V on the POW_SIG is alos on the high side when the STBY power supply is only 5.1V.

[yotsuya]

Re: PE0702A, V28A000962A1 (5V Yes, 12V/24V NO)

Updated readings - AC_DET was indeed an misread in my previous post. It records 0 (or .01 to be exact).
The only readings are
CN90
POW_TV 3.31
Pin 13 (5V1) 5.06

CN91
POW_PRT 3.04
AC_DET .01

The rest are 0 with no changes noted regardless of whether the power button is pressed for any duration.

[budm]

Re: PE0702A, V28A000962A1 (5V Yes, 12V/24V NO)

BTW, do you mean R850 the current limiter resistor, not R851 which is not installed. That R850 will go open circuit if the bypass relay SR81 has bad contacts so the resistor is not bypassed when the TV is in full power mode, common failure.
So the POW_SIG (PS-ON) is not present?
The 'AC_DET .01' should be more than 3VDC for OK, if it is low then it will lock out the PS-ON signal.
Pictures provided by SHOPJIMMY.
Toshiba 75014973 (PE0702A, V28A000962A1) Power Supply Unit.
http://www.shopjimmy.com/toshiba-750...pply-unit.htm#
BTW, all the red cylinder fuses are good, right?

[yotsuya]

Re: PE0702A, V28A000962A1 (5V Yes, 12V/24V NO)

BTW, do you mean R850 the current limiter resistor, not R851 which is not installed. That R850 will go open circuit if the bypass relay SR81 has bad contacts so the resistor is not bypassed when the TV is in full power mode, common failure.
So the POW_SIG (PS-ON) is not present?
The 'AC_DET .01' should be more than 3VDC for OK, if it is low then it will lock out the PS-ON signal.
Pictures provided by SHOPJIMMY.
Toshiba 75014973 (PE0702A, V28A000962A1) Power Supply Unit.
http://www.shopjimmy.com/toshiba-750...pply-unit.htm#
BTW, all the red cylinder fuses are good, right?

Yes, your right R850. That's the fuse that was open and was replaced as well as the voltage regulator at Q880. That brought back some life and the relay SR81 engaged. I also cleaned the relay contacts as part of the initial repair attempt.


F895 - I'm getting something odd compared to the other red fuses. My tone is steady on and off, not solid like the other fuses.. Going to investigate after some regular job duties and dinner. Rest of the red fuses are good. i even replaced on from the shopjimmy repair pack.
You also correct, POW_SIG (Pin 2, CR91) not present (0 Reading). Yes, an error in my initial post. Readings from post 8 are latest. Apologies for any confusion.

[yotsuya]

Re: PE0702A, V28A000962A1 (5V Yes, 12V/24V NO)

Status: Bad Fuse at F895. Going to replace with a Littelfuse Inc. 37015000000
The one below seems to match.

http://www.digikey.com/scripts/DkSea...62724773549168

Make sense? Should I check anything else beside all my other fuses again?

[yotsuya]

Re: PE0702A, V28A000962A1 (5V Yes, 12V/24V NO)

Well, I'm stumped.

I replaced the bad fuse at F895 and now I get AC_DET 3.2, POW_TV 3.31, 5V1 is 5.06 and POW_PRT 3.04. The rest is 0 regardless of power button depressed states.

CN90
1 GND GND
2 GND GND
3 18V_Audio w/load 0
4 18V_Audio w/load 0
5 5_24V w/load 0
6 GND GND
7 POW_TV 3.31
8 GND GND
9 12V w/load 0
10 12V w/load 0
11 12V w/load 0
12 GND GND
13 5V1 5.06
14 GND GND
CN91
1 POW_PRT 3.04
2 POW_SIG 0
3 AC_DET 3.2
4 POW-LCD 0
5 GND GND
6 GND GND
7 12V_LCD w/load 0
8 12V_LCD w/load 0

[sibemolll]

Re: PE0702A, V28A000962A1 (5V Yes, 12V/24V NO)

Hello everyone.
I was testing my tv that wasn't even going standby and when I plugged my multimeter in the two external legs of Bridge rectifier, the relays suddenly closed and the TV started working. After turning off the TV and unplugging the energy the tv stopped working and is dead again.
What could be causing this problem.???

[tvtimmy]

Re: PE0702A, V28A000962A1 (5V Yes, 12V/24V NO)

Maybe a bad solder joint or two......
Pull it and touch-up all the joints that are screwed to heatsinks.

[Badger237]

Re: PE0702A, V28A000962A1 (5V Yes, 12V/24V NO)

Hi everyone,
I have this exact board... The problem I found is that the 5V relay (SR81 I believe) gets 5V at the coil ( When I short 5V1 to POW-TV), but doesn't close because there is no current flowing. Where does the circuit for the coil of SR81 go to ground?

Also, as of right now I have replaced R850 and do get a steady 5V on 5V1. Finding a service manual has proven impossible. I am an electrical engineering student so I know a thing or two, but I have checked all of the capacitors, diodes, shottky diodes, optocouplers, and I have tested the relay out of circuit.

[Badger237]

Re: PE0702A, V28A000962A1 (5V Yes, 12V/24V NO)

Also I should add this TV was rendered inoperable by a lighting bolt that hit my chimney and arc'd over to the antenna and continued to destroy every TV in my house that was connected via coax. I'm guessing the main board is toast, but the power board is showing promise after putting in about an hour and 1 dollars worth of parts. If I can prove to myself that the power board works, I plan on confirming the main board is dead and then replacing it.

[Badger237]

Re: PE0702A, V28A000962A1 (5V Yes, 12V/24V NO)

And, as a third note, it appears that it is actually SR80 rather than SR81

[nomoresonys]

Re: PE0702A, V28A000962A1 (5V Yes, 12V/24V NO)

Try test #3 below.

[Badger237]

Re: PE0702A, V28A000962A1 (5V Yes, 12V/24V NO)

POW-TV has 3.2V
5v1 has 5V
Everything else is Zero
The power button changes nothing.

[dick_barton]

Re: PE0702A, V28A000962A1 (5V Yes, 12V/24V NO)

One ebay repair kit has the following parts.
Kit Includes - so worth checking those components on the power supply

4pcs FETs (Q820, Q821, Q860, Q861)
1pcs Cement Resistor (upgrade to KOA resistor)
2pcs Resistors
2pcs Fuse