Panasonic 65" VT20 10 blink code

[budwich]

Re: Panasonic 65" VT20 10 blink code

hmmm... not sure where you are at with this. was this "pin 5 test" with the good board or the bad board? Further, if it was the bad, did you measure the other voltages? I think by lowering the FB (pin 5)... if I read the sheet, it lowers the frequency of the "chopper" and thus it might now be in your audible. Not that it means much other than, at the higher frequency, the thing doesn't appear to work.

looking further at the "spec" (if it is the right one), if you can find the zener diode on the output of two and check it... maybe its bad / breaking down.

[infrag]

Re: Panasonic 65" VT20 10 blink code

Well I've been a bit of a barbarian and tried my idea of putting some stable voltage on the input pin 5 (or what I assume it is from budwich's comment previously)

I tried with 0.6V but it didnt like that so i tried lower. I put 0.2V on it and tried turning the set on. Made a bit of a squeaky noise but the set did turn on!

So now I guess I should check why that voltage isnt stable on it own in circuit...

[infrag]

Re: Panasonic 65" VT20 10 blink code

Unfortunately I don't have an ESR meter yet. Its still on the way...
This means I can only check to see if the caps aren't shorted or have a guess at someone of them and hope I don't wreck them taking them off and back on again to check capacitance.

Basic checks there are no shorts there that I can see. Might be the other side of the board but so far I'm at a dead end.

[infrag]

Re: Panasonic 65" VT20 10 blink code

The ? Means the voltage goes up for a split second and drops off before I can get a reading. My assumption is its because there is either a short or over voltage condition somewhere along the line. Or the ic is stuffed or both.

The earth pin I'll remeasure. The probe might not have been on 100% . I measured the pins before I knew what they were all meant to be...

As for the input pin idea I could cut the trace and put 0.8v on it like the other board or not a good idea?

[budwich]

Re: Panasonic 65" VT20 10 blink code

IF the datasheet / ic is the same as provided, the pin (5) in question is an "input" to the ic so you need to trace the tracks along the way to find out where its getting that info. Possibly a broken trace or a burnt resistor.

forget this...
As suggested by tn245, check your grounding measurements as the voltage measured there seems out of place. Interesting that you seem to be having "issues" with two sets in and around grounding and the like. :-(

I would check all the capacitors around this ic. Your pin 3 is also suspect ... the "?" means what?

[tn245]

Re: Panasonic 65" VT20 10 blink code

What's the resistance between pin 2 and gnd on both boards?

[tn245]

Re: Panasonic 65" VT20 10 blink code

To be honest I'm just poking around in the dark same as you. I didn't manage to fix my board yet. On mine I'm suspecting either something up with the gpu or the software. It was a board from a cracked screen TV and arrived wrapped in plastic cling film so maybe static damage?

Your board's got a bit more to go on I think. Was on the wrong service manual previously but got the right one now. You're getting the panel on signal but LED 6V (or 8V? - they seem confused in the manual) is missing potentially causing the 10 blinks sos.

Do you have everything hooked up and measuring the same way when testing both boards? I'm wondering why you've got 0.8V on a gnd pin (pin 1).

Datasheet for the ic is here assuming same as on my board:
https://www.digchip.com/datasheets/p...S-Z-LF-pdf.php

The IC could be bad but also could be other components around it or even further down the line. Shorted ceramic caps are reasonably common. You could compare resistance readings to gnd on the pins of the ic. Maybe others with more knowledge can help interpret what's going on based on the datasheet for the ic.

[infrag]

Re: Panasonic 65" VT20 10 blink code

Checked all the test points. The 6v led point is the only one not coming through. Can't find the faulty part around it so I guess I'll have to assume its the IC? Can I bypass it put a separate 6v power supply on it to test?

[infrag]

Re: Panasonic 65" VT20 10 blink code

Double post

[infrag]

Re: Panasonic 65" VT20 10 blink code

Out of interest did you fix your board? If so what part(s) were broken?
Do the IC's normally fail or the supporting parts nearby them on these things?

[infrag]

Re: Panasonic 65" VT20 10 blink code

I spent quite a bit of time chasing down a 10 blink on a GT20 board recently. 10 blinks is the same SOS on that board.

SOS is: Sub 5V, Sub 3.3V, Sub 9V, Tuner Power, MIHO 3.3V, LED 8V.

Went through the service manual finding each point to test on the schematics and then finding the relevant point on the PCB map further down. Sorry I didn't keep a note of where each point is. Quite a few of the points are on the back of the board. I found I could support it with one hand and test with the other to get at the back of the board. I had all those voltages except for MIHO and LED but looking through the schematics those voltages would not appear unless the panel on signal was generated at the MPU which didn't seem to be happening. I didn't get any further with it sadly but would be interested if you do.

Maybe check out IC5811 - 8 pin ic on the top side, toward the left edge near to connector A20. Pin 4 should tell you if you're getting PANEL_STBY_ON, then the bottom side of L5814 inductor just below it should be your MIHO 3.3V.

IC5811 was the IC located higher up the board.
IC5808 is the one near connector A20.
I've checked it out on the bad board and good board and finally I've found some differences in voltage. Thanks!

Bad board pin:
1. 0.8V
2. Starts higher but drops off before I can get a reading so ?
3. ?
4. 3.27
5. 0.6
6. ?
7. 5.2
8. 15.89

Good board pin:
1. 0
2. 8
3. 12.75
4. 3.27
5. 0.8
6. 5.1
7. 5.2
8. 15.89

So yes I seem to get panel on but I have a problem with LED 8V at least.

[tw2005]

Re: Panasonic 65" VT20 10 blink code

Can you test on the bezel the resistance from the surface of the EMI strip to the frame its stuck to? Does the resistance change if you push harder on the surface of the EMI strip?

I did not notice but about 2 ohms

[tn245]

Re: Panasonic 65" VT20 10 blink code

I spent quite a bit of time chasing down a 10 blink on a GT20 board recently. 10 blinks is the same SOS on that board.

SOS is: Sub 5V, Sub 3.3V, Sub 9V, Tuner Power, MIHO 3.3V, LED 8V.

Went through the service manual finding each point to test on the schematics and then finding the relevant point on the PCB map further down. Sorry I didn't keep a note of where each point is. Quite a few of the points are on the back of the board. I found I could support it with one hand and test with the other to get at the back of the board. I had all those voltages except for MIHO and LED but looking through the schematics those voltages would not appear unless the panel on signal was generated at the MPU which didn't seem to be happening. I didn't get any further with it sadly but would be interested if you do.

Maybe check out IC5811 - 8 pin ic on the top side, toward the left edge near to connector A20. Pin 4 should tell you if you're getting PANEL_STBY_ON, then the bottom side of L5814 inductor just below it should be your MIHO 3.3V.

[infrag]

Re: Panasonic 65" VT20 10 blink code

not right now, maybe tomorrow evening plus it's screwed together. Time for some zzzzzzzzzzzzzzzz s

Any chance you'll have time to do it on the weekend?

[infrag]

Re: Panasonic 65" VT20 10 blink code

I have gone around this board IC by IC comparing voltages to the working board I have as reference. I cant for the life of me figure out what chip/voltage is not being produced. Everything I can find is identical or close enough not to be an issue. I've compared voltages on the connectors and they are the same. I've got a whole bunch of IC's that I've compared leg by leg and they are the same. I havent tried the back of the board yet as thats harder to do plugged in...

Anyone got any pointers or experience with this kinda thing?

I'm probably wasting my time on this but I'm waiting for a guy over east to pull apart his TV this weekend and send the parts over so I figure I've got nothing to lose by trying to compare/repair this board.

Even if I find the part thats wrong with it I'd be happier

[infrag]

Re: Panasonic 65" VT20 10 blink code

not right now, maybe tomorrow evening plus it's screwed together. Time for some zzzzzzzzzzzzzzzz s

OK thanks for your time and help regardless!

[infrag]

Re: Panasonic 65" VT20 10 blink code

Quick upload of what I'm on about. Hope to add some other ones without flash tomorrow.

https://drive.google.com/open?id=0B-...k9wMmpWc0tBOGc

[infrag]

Re: Panasonic 65" VT20 10 blink code

I've been comparing read outs of each board. The only difference found so far is a resistance value for Q4201.
I think its pin 6 to pin 3 gives a reading on the bad board of 34 ohms while the good board has 65 ohms.

The schematics I have are apparently wrong and doesnt have that chip in them. I guess I got a similar manual but not the right one.

[tw2005]

Re: Panasonic 65" VT20 10 blink code

Its a socket I believe on the A board. You can use an arduino to interact with the EEprom and read and write to it. The thread calls it a service port. I havent done it so I didnt look too far into it.

This is the guide someone made if your interested in the information.

http://panasonic.mironto.sk/

Sounds interesting, maybe you could try it yourself and contribute what you find.

I'd be interested in say clearing fault codes of adjusting the hours for exmple replacing A boards to match up with the original board but doing eeprom swaps carries the DNA of the old TV across anyway.

I guess people have gone a step further which is cool .

I have stumbled across a couple of 1 blink errors which traditionally people would just replace the Aboard but I got lucky with one reflashing the panel data eeprom.

It was incredible, just one character somehow got corrupted and changed, that killed the whole TV. Found it doing a comparison of a dump file.

I find they're pretty good anyway, but I don't sit in front f my Tellie wondering about my black levels.

[infrag]

Re: Panasonic 65" VT20 10 blink code

Which port? Never tried, don't have the knowledge or gear but would not surprise me but i don't know where you'll find the info for that.

Its a socket I believe on the A board. You can use an arduino to interact with the EEprom and read and write to it. The thread calls it a service port. I havent done it so I didnt look too far into it.

This is the guide someone made if your interested in the information.

http://panasonic.mironto.sk/