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Old 11-04-2017, 05:26 PM
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benman94 benman94 is offline
Resident Lunatic
 
Join Date: Jun 2011
Location: Detroit, MI
Posts: 1,190
Houston, we have (something approximating) a raster!

I decided to bring the chassis up on a Variac again to see what if anything I could get. That's when I noticed that the filament of the third 5U4 wasn't glowing. I could have sworn I checked all the 5U4s when I did the first check, but I must have missed one.

Anyway, I inserted a replacement, and was greeted by an angry sounding horizontal section and fireworks show in one of the 3A3s, along with an extremely faint pulsating raster. I replaced it, but not without knocking myself on my ass from the residual HV first, and was greeted by a very bright, stable squished raster.

In the photo, you'll see a slight light blue glow on the inside surface of the neck. I believe this is NOT gas, but rather stray electrons striking the inside of the glass. This is a normal phenomenon, and most beam power tubes and vacuum rectifiers exhibit this, at least when new.

It ain't purty, but it proves that the set is restorable and more importantly, the the 15GP22 has some life in it yet.

Something is FUBAR in the vertical section, but given that I haven't recapped the set yet, this isn't surprising. I'll let Nick deal with it when the chassis gets to Maryland.

Needless to say, I'm ecstatic.

Electrons striking inside of glass?



First feeble pulsating raster (bad 3A3):




Much brighter raster with the new 3A3 and healthier HV:


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