Sony KV-2643R score

[freakaftr8]

Always wanted this one. Well I picked it up curb style tonight down the street in my neighborhood. A sign taped to the CRT says not working. Oh well. Loaded it up in the back of a Prius and drug it home.

Red gun is extremely tired. (Typical since its driven the hardest) Green almost there too. Blue is bright as day... Typical for these early 26 inch Trinitron CRTs.
Played the screen and drive game and was able to achieve a somewhat watchable picture.

I've changed a few of these Trinitron CRTs in the past. Never attempted a rejuvenation. From what I hear its usually a no go.

I'd have to tap it in to my SENCORE cr161 as it doesn't have the proper socket.

Anyone attempted a successful rejuvenation on one of these ever? I figure maybe give it a shot. Got nothing to lose. Trinitron CRTs are not happy when bumped huh..

[zeno]

Never had a Sony rejuve & last more than a day. What works
usually is bringing up the filament. Jump out the low value resistor
in series with the filament up on the CRT board. Slight risk it will
short but you got nothin to loose.

73 Zeno
LFOD !

[freakaftr8]

True. I'll give it a whirl. Something tells me that these trinitron CRT's don't run at a standard 6.3 V between the heater pins.

[maxhifi]

I attempted to rejuvenate a slightly smaller Trinitron from around that era, with the result being that it got even weaker.

How does it test with higher heater voltage? Maybe you can rig something up to run it like that, instead of the more destructive route.

[freakaftr8]

I was thinking of measuring the H to H voltage across the pins on the CRT neck. This should hopefully give me an idea of what it normally runs at. Even though I cranked around the screen and BKG pots, there is no red BKG pot. This is of course the weak one.

[maxhifi]

Originally Posted by freakaftr8

I was thinking of measuring the H to H voltage across the pins on the CRT neck. This should hopefully give me an idea of what it normally runs at. Even though I cranked around the screen and BKG pots, there is no red BKG pot. This is of course the weak one.

Does this set have filament voltage derived from the flyback? I think that's common on Sony TVs. If that's the case, make sure to check it with a VTVM or meter which has decent response up to 15kHz - an ordinary DMM may give a falsely low reading here, since most aren't accurate above about 1kHz.

[freakaftr8]

Somewhere I have a Simpson model 303. IIRC, it worked ok, but had a sticky needle that I repaired some years ago. Would the DVM meter be a bad choice because of the frequency the flyback runs off for the ripple in the DC that DVMs cannot pickup?

[freakaftr8]

And would I not be mistaken that this is literally the first 26 inch Trinitron introduced in the US outside the 21 inch?

If so, it's a score to me to add next to my 30 inch KV3000R.

[maxhifi]

Originally Posted by freakaftr8

Somewhere I have a Simpson model 303. IIRC, it worked ok, but had a sticky needle that I repaired some years ago. Would the DVM meter be a bad choice because of the frequency the flyback runs off for the ripple in the DC that DVMs cannot pickup?

They run the filament off high frequency AC, not DC. A DVM usually starts to read low as frequency increases, getting grossly inaccurate by the time you get up to approx. 15kHz (flyback frequency)

Someone correct me if this era sony doesn't power the filament this way, but I'm pretty sure they do. At one point you could buy Sony specific brighteners, which were small high frequency transformers intended to boost the filament voltage off the flyback.

Here is an example https://www.ebay.com/itm/SPB2-ISO-Is...-/182417131479

Before proceeding, make sure the filament in this TV really is powered from the flyback

[freakaftr8]

Sorry I meant AC. I'll take some pictures tonight, however the neck board states an R, G, B, G1 G2, I believe and H and another H. Assuming this would be a yes since there is no single pin H and a Ground for H (heater).

Only speculation here of course. I may have it backwards.

[freakaftr8]

Ok so it looks like the voltages that drive the filaments are derived from the flyback. This would require me to put my Simpson to the task, if I can find it.

Here are the pics of the pinouts. I see the resistor on H1 tied to G2. It's a 220kohm. What's that about? Going to H2 looks like a sony proprietary inductor of some type. Dont see that changing voltage.

[freakaftr8]

Well in a turn of events, I went ahead and cranked up the screen drive, sub brightness and sub contrast all the way up.

5 minutes in to a bright green raster, the red popped back!

Would this technically act like a rejuvenation when g2 voltages go extremely excessive?

I'm going to run this hard like this and then readjust the drives in a few hours. Maybe the ramped up g2 drives cleared this out?

[freakaftr8]

So I backed down all the adjustments to where I started, and noticed the red is now being driven towards center. The screen pots for B and G are damn near at centerline to achieve a good white balance. I have the BKG at centerline as well on all three pots.

I cranked everything up to max until I had a bright green screen with retrace lines, then it went to yellowish then red popped in. I left it like this for 20 minutes and backed it down. Then let the set cool for an hour and it stayed the same.

Well see how long this lasts I guess. Picture is pretty decent now. Just a bit out of focus around the corners, and if I turn up the picture level too high, I get green or red smearing. (Weak CRT still I'm sure due to poor focus tracking on the corners and sides of the CRT which will not pull in). I suppose I can always connect my anode probe to see if I have close to 30kv.

[freakaftr8]

Ok. I have been reading back on old posts.. There was a discussion between a few members about "Econoquick"..

This design is meant to leave a few volts at the heaters when the tv is off, not half, or full voltage. I have a feeling that Sony designed this device while the energy crisis of the 70's was in full swing. Sony probably knew something.. If they couldn't get away with half voltage cause of the guidelines introduced then, they could with econoquick. Something at least had to be there at all times to keep the cathodes clean. My theory is If a Trinitron CRT is put into use, it cant sit for a while dormant with no filament activity or the cathodes will become corroded.. The fact that people probably may have been worried about energy consumption, they may have unplugged the set often while not in use, possibly drastically reducing the life of the CRT. This set set for 25 years stated by the previous owner. She recalls that the picture was perfect before it was put out of service just to replace it with a projection tv. It sat in the garage since unplugged.

[maxhifi]

Her idea of perfect, and your idea of perfect may not be the same thing. That said, it's great to hear you got it going!