Panasonic 65" VT20 10 blink code

[infrag]

Re: Panasonic 65" VT20 10 blink code

Well I have an update.
The replacement IC's came in. I soldered the chip in and turned the TV on. It worked!. I checked output voltage from the IC it was 8.5V. Then I turned the TV off.... and tried to turn it back on again. The relay clicked to turn on and then the TV turned off with the same blink code again. Bugger...

The other symptom is the IC does get hot while the TV is on.

Since I've tested most other parts in circuit I feel I'm chasing my tail.

I've done a non normal fix I guess and used a 5v relay to trigger when the 3.3V panel on comes through. This triggers a separate adjustable output voltage regulator which is powered by the 15V and changes it to the required 8V and feeds that back into the circuit.

The long and short of it is that this seems to work but theres obviously some other part in circuit thats not performing correctly. I've had the TV on for an hour and nothing seems to be getting hot.

If it dies I'll just have to get another board.

Thanks very much for the help in finding the faulty area!

[tw2005]

Re: Panasonic 65" VT20 10 blink code

I was going to see if I could just download the eeprom from the A board just in case.

So did you get a clip with yours to clip onto the chip while its still soldered on the board?
Otherwise mine must have been too cheap and missed the whole clip idea...

yeah , came with a clip although it broke and now I can read, but not program so I just take the chip off and solder it onto the board that came with it.

So far I've fixed a corrupted eeprom with it and done a conversion on a new zealand board. Kinda fun transferring the DNA across.

3M and Pomona are 2 brands for those clips. Not cheap, I'll get one one day

[infrag]

Re: Panasonic 65" VT20 10 blink code

HERE.

has a link for downloads, not sure what'll you'll find

https://www.youtube.com/watch?v=L0ChYNwunUE

what sort of playing?

If you're playing with the A boards, copy and save the original contents , label so it can't get mixed up. Pay attention to whether it's a 24 or 25 series chip as the pinouts are different and how you set up the the CH341A too.

If it's wrong you'll see the led go dim, things get hot and then some of that smoky stuff starts to release.

I know the original clip and cable was rubbish, broke after a few uses,

I was going to see if I could just download the eeprom from the A board just in case.

So did you get a clip with yours to clip onto the chip while its still soldered on the board?
Otherwise mine must have been too cheap and missed the whole clip idea...

[tw2005]

Re: Panasonic 65" VT20 10 blink code

Hey do you have a guide to the CH341? I bought one recently and figured I might as well have a play around while I'm waiting for parts

Cheers

HERE.

has a link for downloads, not sure what'll you'll find

https://www.youtube.com/watch?v=L0ChYNwunUE

what sort of playing?

If you're playing with the A boards, copy and save the original contents , label so it can't get mixed up. Pay attention to whether it's a 24 or 25 series chip as the pinouts are different and how you set up the the CH341A too.

If it's wrong you'll see the led go dim, things get hot and then some of that smoky stuff starts to release.

I know the original clip and cable was rubbish, broke after a few uses,

[infrag]

Re: Panasonic 65" VT20 10 blink code

Postage of what?

I'm thinking down the track a bit for the 65"

No manuals will make it hard but essentially if you think of the board as a processor then the only difference between any model is the firmware , data, program loaded on non volatile memory.

some of it is common. So either desolder and swapover or copy the data and overwrite the chips but you'd need a clip.

I've had some fun with a CH341 but the clips supplied are rubbish

Hey do you have a guide to the CH341? I bought one recently and figured I might as well have a play around while I'm waiting for parts

Cheers

[infrag]

Re: Panasonic 65" VT20 10 blink code

you could try utsource but check package and dimensions of what's currently fitted just in case there's more than one package size.

Datasheet has it as SOIC 8, 5mm x 4mm

UTSOURCE has SOP8, which could be an error

expect 3 weeks turnaround

Ordered a couple of them just in case.
Thanks heaps.
I'd never heard of utsource.

Cheapest other one I found was the same price but postage was minimum of $30.

[tw2005]

Re: Panasonic 65" VT20 10 blink code

you could try utsource but check package and dimensions of what's currently fitted just in case there's more than one package size.

Datasheet has it as SOIC 8, 5mm x 4mm

UTSOURCE has SOP8, which could be an error

expect 3 weeks turnaround

[budwich]

Re: Panasonic 65" VT20 10 blink code

but as suggested, do the "comparison resistive" measurement around the chip. This may give you an idea if the chip is indeed the culprit or a supporting circuit component is fried. The "re-chip" is somewhat of a "last resort".

[infrag]

Re: Panasonic 65" VT20 10 blink code

I dont mind to try desoldering/soldering the IC. However I'd like to find and order a backup one or 2 just in case and then try while the backup ones are on the way here.

The problem is I cant find anywhere to order the things to send to Australia

[budwich]

Re: Panasonic 65" VT20 10 blink code

Good progress anyway I think. I was mainly asking for resistance on pin 2 to see if there was a short in the circuit on the output side of the ic dropping the output down. Doesn't seem to be shorted as the 8v you supplied remained, though there is a difference in the resistance reading. I guess you could confirm if it's the ic or not by swapping them between the boards. Resistance readings on all the pins might give some direction too. If you do remove the ics take readings on pads while ics are off. Also a bit of freeze spray may just kick the bad ic into action - maybe try that first. Just throwing out ideas.

I like the idea of "swapping IC" IF you are good at desoldering / soldering packages. It could an "easy" way out.... or not :-)

[dick_barton]

Re: Panasonic 65" VT20 10 blink code

Bad board:
8.1k

Good :

9.3k

What value resistors are connected to pin 2 as in attached diagram marked as R1 & R2

[tn245]

Re: Panasonic 65" VT20 10 blink code

Good progress anyway I think. I was mainly asking for resistance on pin 2 to see if there was a short in the circuit on the output side of the ic dropping the output down. Doesn't seem to be shorted as the 8v you supplied remained, though there is a difference in the resistance reading. I guess you could confirm if it's the ic or not by swapping them between the boards. Resistance readings on all the pins might give some direction too. If you do remove the ics take readings on pads while ics are off. Also a bit of freeze spray may just kick the bad ic into action - maybe try that first. Just throwing out ideas.

[budwich]

Re: Panasonic 65" VT20 10 blink code

measure the same points in reverse as there is a diode in the circuit which maybe impacting measurements.... maybe. It doesn't look good for the IC based on some of your work to date. But possibly do some more resistance check comparison between the working board and non-working. This may give you some further pointers to either the IC or supporting / connnected circuit component issues.

[infrag]

Re: Panasonic 65" VT20 10 blink code

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

Bad board:
8.1k

Good :

9.3k

[infrag]

Re: Panasonic 65" VT20 10 blink code

Anyone know where I can buy that IC?
MP2396ES

C0DBAYY00727

[infrag]

Re: Panasonic 65" VT20 10 blink code

Well I tried a bit more experimenting but everything seems OK.

If I put 8V on pin 2 output everything works. I do have to wait till the IC tries and fails to start itself otherwise it goes ballistic and starts outputting 14.5V which is dangerous I guess.

Anyway I turn the TV on... wait for the IC to try and start and give up. Then give it 8V from external powersupply. Everything is happy and hardly and power draw from the powersupply.

The IC voltages are then:

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

So everything seems happy and the TV runs sweet.
I checked the service menu and it reckon the TV power on time is 222 and turned on and off 192 .

Anyway does it make sense then that this IC is just stuffed or maybe its too sensitive in detecting a short?

[infrag]

Re: Panasonic 65" VT20 10 blink code

OK I gave the bad board 0.1V on pin 5 again.
The voltages then are stable (for the brief moment I let it stay on as they are obviously wrong)

1. 0V (Ground)
2. 11.47V (too high should be 8V)
3. 15.4V
4. 3.3
5. 0.1V (I didnt check this pin if it ended up higher or not)
6. 0V
7. 5V
8. 15.89

The TV turns on like this but I dont want to leave it on with 11.47 instead of 8V.

I might see if I can make up a separate circuit from pin 5 to pin 2 as described in the IC datasheet.
Maybe something is dragging it down so its not getting the input it needs.

[infrag]

Re: Panasonic 65" VT20 10 blink code

well it doesnt appear to be the diode. I've tested it and it appears OK. Tried a replacement and that does the same thing anyway.

[infrag]

Re: Panasonic 65" VT20 10 blink code

Excuse my ignorance but is there a way to test the diode in circuit?
I realise I could check voltages on the pins when its on but since its only on for a split second before voltage drops how can I check this?

I've tried removing the diode from the board but its been a pig and I feel if i try anymore I'll wreck it.

I do have some non surface mount diodes lying around but I have no idea what specs they need to have if I had to replace it.

[infrag]

Re: Panasonic 65" VT20 10 blink code

I did my pin 5 test with my bad board. I couldn't at the time check the other voltage while I was doing this.

Thanks for the feedback. I'll check it now.