Sony KV-1320U (Japanese market) Trinitron restoration

[cj_reha]

I've been taking a break from some other longer-term TV restoration projects, and this set came up in my regular Japanese auction site searches. I have a soft spot for early Trinitrons, and this set was cheap, so I decided to spring for it. It arrived the other day, and I have to say, I am amazed!



It is in nearly immaculate condition. The plastic and cardboard knob protectors are intact and there are basically no dings or scratches anywhere. I honestly think it is one of the nicest sets I've ever owned.





One problem: the CRT is stone dead! It's always the nice ones! At first it tested so poorly I genuinely thought something might have happened to my CRT tester - the needle did not move at all. After a few minutes I saw it move a millimeter or so, and sanity checks revealed my tester was fine - it really is just gone. I let it bake overnight at a slightly elevated filament voltage and managed to get about a quarter inch of deflection, but nowhere near what could even be considered "usable."



I took the back off and did some basic checks to ensure the crucial parts weren't blown up, and a slow power-up produced a very dim, green picture. The good news is I now know most of the set is basically working, and I hope I won't have to go too far into the rabbit hole of early Trinitron troubleshooting. But I need a source for a 330AB22 CRT - not an easy ask these days!



Here's my plan. I have a less nice, standard US market KV-1203, one of the later "Econoquick" sets, that works and has a decent 330AB22. As much as it pains me to do so, I think I am going to use it as a CRT donor as nondestructively as possible. None of the early Sonys are particularly common, but I personally like the 1320U more, it's rarer, and think its exceptional condition makes it worthy of a full restoration. I will keep all the parts together for the 1203, though, in case I someday find another CRT.



I am very curious to see how this set differs from its American counterpart, the KV-1220U. At a cursory glance I see a few things I can elaborate on in a later post, but the bulk of the parts seem to be the same (good news - the American service manual is wonderfully verbose and helpful!)

More to come very soon!

[vol.2]

Amazing set. Looking forward to updates!

When you say you let it "bake overnight," what exactly did you do?

I'm asking because I have the same Sencore tester, and I want to do that to one of my tubes. I have zero experience using it, so I need a little help with these tricks.

[cj_reha]

Originally Posted by vol.2

Amazing set. Looking forward to updates!

When you say you let it "bake overnight," what exactly did you do?

I'm asking because I have the same Sencore tester, and I want to do that to one of my tubes. I have zero experience using it, so I need a little help with these tricks.

Basically, letting the tube sit with a slightly elevated filament voltage for a prolonged period (I usually let it go overnight). Think 7-8 volts for a standard 6.3V filament. I have found this to bring emissions back in a fair number of CRTs without having to go the potentially destructive route of rejuvenation. It even kinda-sorta worked with this one, but Trinitrons are infamous for dying hard deaths, and this one is unfortunately no exception.

[Electronic M]

I've done the same on my B&K 466. I'll leave it sit in test mode at normal heater voltage for maybe 10 minutes and if that doesn't do it I'll bump up the heater as much as 1.4x rating and let it sit as long as I want. Trinitrons are known to die when actual rejuvination is done (even on gentle rejuvinators) so the above is about the only practical thing you can do for a weak Trinitron unless afterwards it's still so dead that you've got a nothing left to loose.

[vol.2]

I have heard tell that the "restoration" setting on the Sencore units is actually good for this.

It doesn't "rejuve" the guns, it just does elevated heater voltage and beam current at the same time.

[cj_reha]

Originally Posted by vol.2

I have heard tell that the "restoration" setting on the Sencore units is actually good for this.

It doesn't "rejuve" the guns, it just does elevated heater voltage and beam current at the same time.

It is essentially the same process, just with a much lower current over a longer time. Definitely gentler, and my first escalation when trying to resurrect a CRT I care about. But I honestly find in most cases, just baking the tube at an elevated filament voltage works fine

Anyway, some progress over the past couple days. I got the donor set split apart and the CRT removed and cleaned.



Much better!



Over the next couple days I will similarly split the 1320U apart. No broken yoke plastics so far - wish me luck!

I've been studying the chassis and comparing it to the photos and documentation I have for its American counterpart, the KV-1220U. A major difference I see right off the bat is a voltage selection tap for 100 or 110V, as well as the fact the set substitutes a circuit breaker for regular glass fuses, of which there are three:



I have, of course, moved the fuse to the 110V tap, but am still presently running it off a variac to be as gentle to the power supply circuits as possible. I may experiment with lowering the B+ at full line voltage to make it slightly less inconvenient to use, but that will be a project for when the set is set up and just about wrapped up.

One last thing. Does anyone happen to know a good substitute for these neon bulbs? There are four on the neckboard being used for arc suppression. The Sony P/N is 1-519-013-13. It appears the circuit glue went corrosive and is eating the leads on all four (one even fell off!). For the life of me, I cannot find an industry equivalent for these or any kind of cross-reference at all, and of course they are not for sale anywhere I've looked, even the surplus sites that are pretty good at keeping weird parts. For now, I can scavenge some from the KV-1203 which uses a few of the same type, but it's not an ideal situation.



More soon!

[vol.2]

Looks awesome. Going to be a beautiful set when done.

Originally Posted by cj_reha

But I honestly find in most cases, just baking the tube at an elevated filament voltage works fine

So I would just hook up the tube and turn the heater voltage on the Sencore up and let it sit?

I seem to remember someone advising me to also have current running to the cathodes while doing this for the proper effect, but then I've also encountered suggestions for just leaving the heater at like 8-10Vs or something and letting it simply sit there.

For now, I can scavenge some from the KV-1203 which uses a few of the same type, but it's not an ideal situation.

Can you just solder some new leads onto the old neon bulbs? If they are still functional, there's no reason that you can't reuse them.

[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

[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.

[dtvmcdonald]

Tom: I bought a Sola transformer to power my color and pre-WWII sets. Its a 1 kW unit and works great.

But it hums loudly and drives me crazy, so I'm still using a Variac and a
Kill-a-Watt to set it.

Do you know here to get constant voltage transformers that don't hum or buzz?

[maxhifi]

Originally Posted by dtvmcdonald

Tom: I bought a Sola transformer to power my color and pre-WWII sets. Its a 1 kW unit and works great.

But it hums loudly and drives me crazy, so I'm still using a Variac and a
Kill-a-Watt to set it.

Do you know here to get constant voltage transformers that don't hum or buzz?

The Sola will always buzz, as will any saturated reactor type voltage regulator. An electronic power supply would work, but is expensive. For Old TVs I think your variac method is great, if you can spare a variac.