Canadian Rogers 17" TV

[Gregb]

Hi All:
Need a little guidance with my Rogers set, I have recapped it and replaced a few resistors as well and it is working pretty good except for one issue. When I turn up the brightness control the picture gets bigger like it is being magnified, goes out of focus, and then goes dark instead of getting brighter. I can get a pretty good picture if I get the right balance between the brightness and contrast but it is not very bright just ok if you get what I am trying to say.
Any thoughts?
Thanks

Gregb

[old_coot88]

Classic case of 'blooming' caused by HV dropping under load. Due to weak HV rectifier in 99% of all cases.

[Gregb]

Thanks old coot, your right. I had installed a brand new RCA HV rectifier and had 16KV and when I just checked it was under 10KV and fluctuating with the picture. I installed another new tube and its right back up to 16KV again. Is there something I should check? Seems strange that a brand new tube would go bad so soon.
Thanks

Gregb

[jr_tech]

A small percentage of tubes may be leaky and become gassy in the box, or develop a leak when first operated. The "new" RCA tube could well be 50-60 year old "new old stock", I don't think anybody is makin' TV HV rectifier tubes (1B3?) anymore.
Can you see a date code anywhere?

jr

[Gregb]

It is a NOS tube and I didn't see a date code but by the looks of the box would say it was 50's vintage. The Sylvania I replaced it with has date code of "DG", not sure what that translates to. I have a pile of these NOS tubes from an estate I bought out. The guy had hundreds of brand new never opened tubes.

Gregb

[Gregb]

I just tested the RCA in my tube tester and it didn't even come up to 10%, the new Sylvania tested at 100%. Hope it was just a bad tube and not a problem in the set.

Gregb