20 year old Sony (UK Pal) - Videokarma.org TV - Video

Combwork · #1 07-01-2009, 07:59 AM

Hi,

Despite being at least 20 years old this 25" set works well. But last night it fired up with a good picture, but also a ticking sound from the back; about once every couple of seconds. With the back of in the dark I saw a spark from the casing of the line output transformer to a middle size capasitor. It seemed to the side of the cap but maybe it was tracking through dust. I cleaned it, gave it a squirt of switch cleaner to wash anything off that was stuck to, fired the set up and all seemed well. Then after a few minutes the ticking started again; only once in about thirty seconds but still there so I bent the capacitor away from the LOPT and all seemed well. Except now there was a continious fizzing sound from the EHT cap on the tube, the kind of sound you get if you turn the EHT up too high. I turned the set off but wasn't able to pull the connector off so put a good layer of plain silicone sealer under the rubber cap. There were traces of old sealer under it anyway; no servicing has been done on this set so I guess it was there from new.

For years there has occasionally been a few loud 'cracks' from the back, but after about 5 minutes they stop. I've just left it; maybe it was caused by damp? I've left the sealing on the EHT cap overnight to give it a chance to fully cure. If the fizzing has gone do you reckon this is OK? If I could find the EHT voltage adjuster I'd back it down a bit; better a slightly softer picture than anything arcing over; I had this with an old tube color TV and it's not funny........

AndrewM · #2 07-01-2009, 06:19 PM

Silicone sealant should be OK to cure your problem. It's best to use "non-acetic" silicone as the normal stuff produces acetic acid when it cures which can cause issues.

If the set has stopped sizzling then all should be good. Damp is certainly an issue, I've recently had a couple of sets runnning that were fine in summer but are now busy sizzling away due to the damp winter weather.

Combwork · #3 07-02-2009, 03:53 AM

Quote:

Originally Posted by AndrewM

If the set has stopped sizzling then all should be good. Damp is certainly an issue, I've recently had a couple of sets runnning that were fine in summer but are now busy sizzling away due to the damp winter weather.

Thanks,

I think you've hit it. Last night the set made a couple of 'cracks', fizzed for about 20 minutes then went quiet. I live in an old stone house with walls some 17" thick. For the last two days the weather's been very hot but before that, we had a lot of rain. The hot weather begins to warm the damp stone; as it dries out it loses water vapor. Outside this disipates but the air in the room holds the damp. In the evening the sets mostly on and running warm but from around midnight onwards, it's off. As it cools, a little bit of moisture condenses on the back of the tube; maybe the charge held in the EHT supply attracts some of the very fine moisture in the air.........

So for now, my concerns that just like the old DECCA we might have another fire source ticking away in the corner have been calmed down (a bit).