Neo 25 - Toei TC-A252S woes

[NoAffinity]

I just completed a cap kit on this Neo 25 Toei chassis. Lots of caps... I took my time, went methodically. Checked caps as they were coming out for orientation and rating. Checked them again when they went back in. Buttoned up the refresh, reconnected the chassis to smoke test, got good video for about 30 seconds to a minute.

Then...video disappeard and a loud squeal started.

Video of what it's doing, here:

(Ignore my commentary, some of the start of each segment got cut off).

I've gone back over my work multiple times, everything is good for rating and orientation.

I should also mention I recapped the power supply a couple months prior and it's been playing (many times) with no issues since that cap job.

Anybody out there familiar with these chassis and have any suggestions?

[o1s1n]

Just a heads up in case it's any use to you, there's a guy selling NOS Toei flybacks, might be worth looking into see if they're compatible.

https://www.arcadepartsandrepair.com/st ... j-flyback/

[NoAffinity]

Just a heads up in case it's any use to you, there's a guy selling NOS Toei flybacks, might be worth looking into see if they're compatible.

https://www.arcadepartsandrepair.com/st ... j-flyback/

Sweet, thanks. I've actually been talking directly to Peter (owner of that operation). I bought the cap kit from him and have been a customer of his for many years. Very nice, helpful and knowledgeable guy.

[kazuo]

Unfortunately everything I've heard about these indicates they're difficult to fix and generally unreliable. Grant or svgun are probably the best people to ask about them.

Was this one of the cabs floating around on KLOV & ebay recently?

[NoAffinity]

Unfortunately everything I've heard about these indicates they're difficult to fix and generally unreliable. Grant or svgun are probably the best people to ask about them.

Was this one of the cabs floating around on KLOV & ebay recently?

Yeah, having no schematics to work off of makes it a challenge.

I bought this off a klov member quite a few years ago (posts and pics of original acquisition are floating around here on AO forums somewhere). Its been working reliably all these years, monitor is nice and bright. I started noticing some noise in the background of the image, figured it was overdue for servicing. Should've just left it alone, in hindsight.

[NoAffinity]

After a lot of poking, I think I've isolated the issue to this transformer. touching it with a non-conductive pair of tweezers, I can feel it vibrating in conjunction with the squealing. I haven't found any info online on this component. If I knew what the 'Q' logo stood for - assuming that's a manufacturer - I might be able to get closer. Anybody know anything about this device?

[NoAffinity]

I'm happy to report that this chassis is working again. I found the fuse at F1 blown. I had nabbed a parts A292 chassis (29" version), and proved the cab was otherwise working, with the A292 chassis.

These chassis look identical and from everything I compared, all parts are identical. In the process of poking around, I found the fuse at F1 blown on the A252 (original) chassis. I swapped the good one off of the A292, and it fired right up.

I can only assume the reversed cap caused the fuse to blow, and that's what I've been chasing the whole time.

Now then, I also scraped off the glue from the B+ VR, and it is certainly no longer at it's original setting (and probably needs adjustment/verification anyway). Does anyone know what B+ should be set to on these chassis - preferably for the TC-A252S, but if it is known for the TC-A292S, that might get me to the same desired outcome.