Sony KV-1320U (Japanese market) Trinitron restoration

[Electronic M]

What I do on Japanese market gear (VCRs mostly) and some vintage TVs is use a bucking transformer. They're basically heater transformers with the leads wired to form a bucking auto-transformer. You can get them in 6V, 12V, and 24V flavors. My line voltage is around 117V on average so I tend to use the 12V bucking flavor...My 12V bucking was originally wired as a boost but I simply reversed the 12V winding for bucking....no sense tying up a variac on a working unit.

[vol.2]

Originally Posted by Electronic M

What I do on Japanese market gear (VCRs mostly) and some vintage TVs is use a bucking transformer.

Why not just use the heater voltage on a tube restorer?

[jhalphen]

Hi to all,

"Alastair" in the UK claims (in 2013) to have obtained good results reactivating 1st generation Trinitron tubes (the 12" 330AB22) :

https://www.radios-tv.co.uk/communit...ation-updated/

Note: the site is sometimes geo-blocked for security reasons.

Best Regards
jhalphen
Paris/France

[cj_reha]

Originally Posted by jhalphen

Hi to all,

"Alastair" in the UK claims (in 2013) to have obtained good results reactivating 1st generation Trinitron tubes (the 12" 330AB22) :

https://www.radios-tv.co.uk/communit...ation-updated/

Note: the site is sometimes geo-blocked for security reasons.

Best Regards
jhalphen
Paris/France

Interesting - bookmarked, thank you very much! I will try this on the original CRT once I have the set finished. I have nothing to lose and it sounds like a fun experiment.

As far as progress on the KV-1320U: I'm pretty far in to the mechanical part of the CRT exchange. I got the chassis and CRT/front panel divorced without incident; it mostly followed the OEM Sony manual instructions, with an exception for some of the wiring on a terminal strip on the CRT shield. But a quick reference photo took care of that





Miraculously, none of the yoke plastics or mounting hardware broke! I was very pleasantly surprised...





I'm thinking once I have the replacement CRT fully dressed I'll start pre-emptively recapping the chassis before putting it all back together. Not having the yoke and CRT in the way gives me really good access to a lot of parts I'd otherwise really struggle with, and I already know most of the set works as it came up with full deflection and snow. More soon...

[zeno]

The PCB's are hinged so most things are easy to get at.
Zeno

[cj_reha]

Originally Posted by zeno

The PCB's are hinged so most things are easy to get at.
Zeno

Definitely serviceable in situ, but eh, I have it all apart, why not...

Been trying to do the hardest boards first. The IF-related circuits are a bit tedious with all the soldered shields, but I bought a new soldering iron recently which has been making quick work of it all. Metcal RF irons are no joke!





I love these 2SC403A's - seen a lot of them in Sony IF/color circuits. The "leads" appear to be nothing more than gold foil. I have a precious few used spares, but am still super careful working around them. I can't imagine how fragile they are...

[vol.2]

Originally Posted by cj_reha

Metcal RF irons are no joke!

Very jealous! A decent soldering iron is at the top of my list right now, but I don't think it will be quite as nice as that one.

I've been using the same Digital Tenma station that I bought from MCM Electronics in the late 90s. I never bothered replacing it because it kind of "just works" and it gets very very hot. The big issue is that it takes a minute or two to be usable.

I have a precious few used spares, but am still super careful working around them. I can't imagine how fragile they are...

The original parts are still available NOS from some guys in the US on ebay if you are dying to keep it original, but there is also a short form datasheet out there that has all the specs.

[vol.2]

Originally Posted by cj_reha

I will try this on the original CRT once I have the set finished. I have nothing to lose and it sounds like a fun experiment.

Would definitely be interested to see you try to restore it. Although I think it's worth noting that the person who tried that experiment never actually reported on the tube working in a chassis

All we know for sure is that the emissions looked better for at least some amount of time after he did it. It never made it back into use in the scope of that thread

[Electronic M]

Originally Posted by vol.2

Why not just use the heater voltage on a tube restorer?

I'm not taking about CRT testing or restoration there. I'm taking about powering the whole darn TV. You can't power the whole TV from a CRT tester/restorer.

If you wire a 4 wire heater transformer so that one terminal of the secondary connects to one terminal of the primary and connect a power outlet across the other terminal of the seconday and the other terminal of the primary you can make a device that lowers or increases (depending on the polarity of the secondary waveform) the output voltage by the secondary voltage....IE if you have a 24V secondary transformer and a 120V line you can wire the transformer to give you 96V output or 144V output. Japanese electronics designed for 100V don't always like American 125V... bucking line voltage down closer to the rating prolongs the life of the device.

[vol.2]

Originally Posted by Electronic M

Japanese electronics designed for 100V don't always like American 125V.

Ah. Ok makes sense. This comment is specifically because OP is restoring a JDM chassis designed for 100VAC input.

[Electronic M]

Originally Posted by vol.2

Ah. Ok makes sense. This comment is specifically because OP is restoring a JDM chassis designed for 100VAC input.

Yes, but this can be relevant to vacuum tube chassis American electronics too. Some old American stuff designed for 115VAC (as was the norm from WWI through the end of the tube era) isn't always it's happiest with 10 more volts...It usually doesn't matter much but on some sets where horizontal output cathode current is excessive and every repalcable part has been checked and it can't be made any lower without adjusting line voltage to the power cord (and or on high dollar early color sets where loosing a flyback is a death sentence) adjusting line voltage for minimum cathode current while maintaining reasonable B+ and heater voltage can be worthwhile. My regular use early colors get their power through a resonant isolation transformer that takes 70-140VAC in and spits out a constant 120VAC then into a bucking auto-transformer that shaves 6V off that (then into the TV) so cathode current and B+ are at a good balance for minimum stress.

If you stick with American SS stuff none of this matters, but I'm mostly a tube chassis era collector.