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Shahid
Shahid, Technician
Category: TV
Satisfied Customers: 9465
Experience:  I have been repairing electronic gear since 1993 as a qualified Sony tech
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I have the same symptoms described here, and the same test

Customer Question

Hi, I have the same symptoms described here, and the same test results, however I replaced the P board and the light still flashes 5 times. Any recommendations for further testing? Thanks.
Submitted: 5 months ago.
Category: TV
Expert:  Shahid replied 5 months ago.

Hello and Welcome. My name is ***** ***** I'll assist you today. I'm sorry you're having trouble with it.

- What is the original issue in TV?

- Does the power light blink 5 times?

Thanks.

Customer: replied 5 months ago.
original issue is power led blinking 5 times. I don't know if it's relevant but this happened after a lightning storm and we could have had a power surge, however there are no obvious signs of blown components in the TV. No other appliances were damaged so the timing with of the TV failure with the storm may just be a coincidence.
Expert:  Shahid replied 5 months ago.

OK, there are several circuit boards involve for 5 times blink error code and a procedure to troubleshoot the bad board, reasons of problem are appended below..

1. Missing P5V

2. A short of the P5V
3. A short of the Vda line (Note: missing Vda from the P board does not cause 5 blinks)
4. Wrong diagnostic by the A board

Lets troubleshoot the problem properly.

Does the power supply makes a “chirp” noise at plug in TV power cord?

Reply back with the result to proceed further.

Customer: replied 5 months ago.
No noticeable chirp, there is some clicking.
Expert:  Shahid replied 5 months ago.

OK, do you have multimeter to check resistance?

If so, disconnect the TV power cord. Measure the resistance between pin 1 of connector P35 on the P board and ground (Chassis).

Is there a short to ground (low ohms reading)?

Customer: replied 5 months ago.
There doesn't appear to be a short. Reading is ~7,800 ohms
Expert:  Shahid replied 5 months ago.

OK, so reading is 7800 ohms, correct?

If so, use a volt-meter and place the positive probe on pin 5 of connector P25 on the P board while the negative probe is grounded. Plug in the TV and turn it On.

Does meter show 5V reading?

Customer: replied 5 months ago.
Difficult to say. When first powered on the reading jumps up around for about a second, then the SOS circuit kicks in, seems to shut down the board, and that pin settles at 0 mV. So should it be a steady 5V even after the SOS circuit kicks in, or just a transient 5V?
Expert:  Shahid replied 5 months ago.

It is switched 5V supply that will turn Off when SOS kicks in. Standby 5V supply is available at pin-9 of P25 connector and would remain stable all the time as far as power cord is plugged in.

If you press power button on TV again, hopefully 5V will again appear, if this happens that means A Board of TV is defective and causing the problem, A board is where all video inputs are located and you would need to replace A board in TV to resolve the problem. I trust my input will help you out. Please feel free to respond if you have any additional questions.
A positive rating to answer would be greatly appreciated, please click on 5 star on this page then click submit/finish button so I can get credit on website for my work. If you don't see rating option then intimate here.
Regards,
Shahid.

Customer: replied 5 months ago.
Ok, I do get the steady 5V at pin-9 of P25, but I really can't tell if pin-5 briefly comes up to 5V or not. There's no steady reading, it jumps up and drains away too quickly. If I press the power button again the board doesn't power up, instead I just get a single blinking light.
Expert:  Shahid replied 5 months ago.

OK, you can again check the volts at pin-5, unplug TV power cord for 5 minutes, replug back in, touch meter lead to pin-5 and press power button, volts should remain till SOS kicks in.

Thnaks.

Customer: replied 5 months ago.
Is there a way to prevent the SOS shutting the board down, or delay it, so we can test pin 5 for 5V?
Expert:  Shahid replied 5 months ago.

I wish there was such a way but we can't bypass the protection circuitry on A board.

Expert:  Shahid replied 5 months ago.

Hi, do you need any further assistance with this question?
Thanks.

Customer: replied 5 months ago.
I don't know yet. I think you were recommending to replace the A board so I'm going to try that. I'll let you know if it solves the problem or not.
Expert:  Shahid replied 5 months ago.

We figure it out during troubleshooting process that A board is suspected and should be swapped.

Thanks.

Customer: replied 5 months ago.
Ok, I swapped the A board and now get a different response...Previously I got 5 lights as soon as I supplied power to the TV (without even pushing the power on/off button on the front.)
Now I get no response when I supply power to the TV, but when I push the power on/off button on the front I get 6 lights.
Customer: replied 5 months ago.
In fact I've done some more testing and I have the same symptom reported here:
http://my.justanswer.com/question/guest/8f68d8c1b76d4e76bee45c58ccbdfa8a"If I disconnect connectors SC2 & SC20, and A board connectors A31 and A32 the unit powers up - Black screen
but fans run and red light on optical audio is lit along with solid (non-blinking) power light on front."
Customer: replied 5 months ago.
Also, now the board isn't shutting down I was able to check the voltages:
TP1 - 322.5V
TP2 - 37.5V
TP3 - 331V
TP4 - 37.4V
TP5 - 199.5V
TP9 - 60.2V
P2 pin 1 - 199.5V
P6 pins 1,2,3 - 16.1V
P6 pins 7,8,9 - 14.6V
P7 pin 1 - 16.1V
P7 pin 5 - 5.16V
P7 pin 6 - 2.82V
P11 pin 1 - 199.5V
P11 pin 4 - 16V
P25 pins 1,2 - 16.1V
P25 pins 5,6,9 - 5.1V
P25 pin 11 - 3.23V
P35 pins 1,2 - 60.3V
Expert:  Shahid replied 5 months ago.

Sorry to hear that, give me little time to check the manual again and get back to you in 30 minutes.

Thanks.

Expert:  Shahid replied 5 months ago.

First of all please make sure all connectors are plugged securely and tight on circuit boards, especially on SC, SU, SD and A boards. If still get 6 blinks error code then verify that all the cables plugged in to the SC and SS boards are properly seated. Also check the ribbon cables and connectors on the A and C boards. Unplug the TV power cord and disconnect connector SC20 on the SC board and the ribbon cable between connector C10 on the C1 board and connector C20 of the C2 board. Plug in the TV and turn it on.

Does the number of blinks change now?

Customer: replied 5 months ago.
it goes back to 5 blinks after disconnecting SC20 on the SC board and the ribbon cable between connector C10 on the C1 board and connector C20 of the C2 board.
Expert:  Shahid replied 4 months ago.

OK, do you still have old A Board and can put it back in TV to get previous symptoms?
New A board seems doubtful and old A board installation will help here, if you get previous symptoms then new A board seems defective and should be contacted to supplier to return this one to get another A board.

Thanks.

Customer: replied 4 months ago.
I do still have the old A board. Which test do you want me to execute with it?
Expert:  Shahid replied 4 months ago.

No special test with old A Board, since new A board gives 6 blinks error code that is bit odd so we can confirm the other boards in TV by installation of old A board to see if TV gives 5 blinks error code?

Customer: replied 4 months ago.
Ok, well this is confusing but I just re-connected everything with new A board and I now have 5 blinks (not the 6 I had when I first installed this board). Should we proceed from here rather than re-installing the original A board? Also, question, how long should I wait between tests after powering off the TV to make sure the SOS circuit is properly reset?
Expert:  Shahid replied 4 months ago.

I'm running out of ideas what is causing the problem, let me repost this question so other experts can have a look and hopefully some one will soon respond to assist you further.

I'm opting out to repost the question.

Thanks.