Technika LCD32-229 Freezing / Restarting Issues

[TechWizard.Support]

It uses a Vestel 17PW26-4 PSU which I replaced 3 Months ago.

After around 10-15 minutes usage with no issues, the sound begins to crackle, slight pixelation and then it freezes, reboots and the problems repeat.

I have re-tuned the TV, tried on two different aerials at two different locations. The signal is strong in both locations, and I do not believe this to be the issue.

I'm new to TV repair, could anyone point me in the right direction? Do you think it likely to be an issue on the power board or main board?

Thanks in advance

YouTube link to a short video of the issue:
https://youtu.be/k8-gemQMaXI

[nomoresonys]

Re: Technika LCD32-229 Freezing / Restarting Issues

https://www.youtube.com/watch?v=mUvclBfaMXg
Powersupply testing, you don't have to remove the board from the tv tho, just MAKE SURE you disconnect all the other boards/wires going to powersupply board, test with multimeter and see if you have expected voltages, there's usually a little legend/map of the expected voltages close to the connectors.

[diif]

Re: Technika LCD32-229 Freezing / Restarting Issues

The Vestel power supplies are known to have poor quality caps. If you just swapped the board, chances some are out of spec and that's causing the issues you are encountering.

Buy yourself a cheap component tester off ebay to test them or just replace the capacitors with some quality ones like Panasonic FM or FR from RS or Farnell/CPC.

[TechWizard.Support]

Re: Technika LCD32-229 Freezing / Restarting Issues

Thanks for the information. Apologies, I forgot to mention that I have a multi-meter, ESR meter and a soldering/hotair station. I'm quite inexperienced, but I have enough basic understanding to test basic components.

Regarding the replacement power board, it has been working for 3 months and from memory, this had replacement caps - I can't recall the manufacturers, but I will open it up and check. I guess it's always possible something could be on the way out. Regarding testing the voltages, I suspect they will all be OK as the TV operates fine for 15 or so minutes before the problem occurs - so I
need to apply a load in order to replicate the issue. That's assuming the problem is with power.

I was just wondering if anyone has experienced these issues, and whether they can advise me to start troubleshooting the power board (and how, in this situation), or whether the problem is likely to be with the main board?

[CapLeaker]

Re: Technika LCD32-229 Freezing / Restarting Issues

When the TV acts up, use a can of air upside down and freeze some components on the main board like the main IC, the regulators, etc. This doesn't sound like bad caps to me. IF id be bad caps, they like it warm! This is the opposite case.

[nomoresonys]

Re: Technika LCD32-229 Freezing / Restarting Issues

Sometimes you get lucky with a factory reset or firmware update/reapply but it seems like a mainboard issue.

[TechWizard.Support]

Re: Technika LCD32-229 Freezing / Restarting Issues

Thanks for the help everyone, I've fixed it.

I couldn't replicate the issue with the back off, which was no good for testing! So I presumed it might be an overheating problem. Installing a fan inside solved the issue and I then pinpointed the overheating to the main chip on the main board - popping a heatsink on this seems to have fixed it without the need for the fan. I think I might just leave the fan installed anyway to help with the airflow.

This was a favour for a friend and I've advised them that this isn't likely to be a long term solution as it's the chip is probably on its way out.