Sony KV-2052UB colour decoder problem - UK Vintage Radio Repair and Restoration Discussion Forum

GadgetM · 4th Apr 2020, 4:04 pm

Hello again. My latest restoration project is a sony KV-2052UB, with tinted glass front. A nice looking telly from the mid 80's.
The problem is that at random intervals the colours go all strange. It starts out with the blacks flickering between neutral dark grey and purple-ish blue, then the screen gets covered in subcarrier noise/grain, I get feint yellow and purple vertical stripes all over the picture and all the colours go screwey. Blacks go purple-ish blue, whites go yellow, yellows go pink and blues go totally green.

I've checked for dry solder joints, I've cleaned all the board connectors, cleaned the preset pots on the chroma board but no joy. In fact these pots (including colour phase) have little to no effect when this problem arises. Oddly the fault can come and go on it's own and nothing seems to trigger it. Tried cooling spray on various components, tried warm air too, but it just does it's thing when it wants to.

Any suggestions would be welcome. Cheers!

GadgetM · 16th Apr 2020, 7:03 pm

I have since abandoned repairs on the tv. Too many new faults developed, decided not to waste any more time on it.

4th Apr 2020, 4:04 pm	#1
GadgetM Tetrode Join Date: Jul 2011 Location: Cardiff, Wales, UK. Posts: 72	Sony KV-2052UB colour decoder problem Hello again. My latest restoration project is a sony KV-2052UB, with tinted glass front. A nice looking telly from the mid 80's. The problem is that at random intervals the colours go all strange. It starts out with the blacks flickering between neutral dark grey and purple-ish blue, then the screen gets covered in subcarrier noise/grain, I get feint yellow and purple vertical stripes all over the picture and all the colours go screwey. Blacks go purple-ish blue, whites go yellow, yellows go pink and blues go totally green. I've checked for dry solder joints, I've cleaned all the board connectors, cleaned the preset pots on the chroma board but no joy. In fact these pots (including colour phase) have little to no effect when this problem arises. Oddly the fault can come and go on it's own and nothing seems to trigger it. Tried cooling spray on various components, tried warm air too, but it just does it's thing when it wants to. Any suggestions would be welcome. Cheers!

16th Apr 2020, 7:03 pm	#2
GadgetM Tetrode Join Date: Jul 2011 Location: Cardiff, Wales, UK. Posts: 72	Re: Sony KV-2052UB colour decoder problem I have since abandoned repairs on the tv. Too many new faults developed, decided not to waste any more time on it.