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  #76  
Old 09-15-2017, 12:16 PM
FrankieKat FrankieKat is offline
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So I might have just hit a "duh" moment here. Reading the barely-legible scanned print at the bottom of the schematic it says "channel selected shown in channel 13 position" and "measurements taken with no signal applied". And well, I had previously been testing voltages with a signal connected. Now, with no signal I get pretty close to all of the voltages on the schematic -- of course with a signal they jump up to those much higher ones.

Based on that, would it be safe to say then that what I'm seeing is in fact the correct, normal working voltages (despite being quite a bit different) when tuned in?

FK

Last edited by FrankieKat; 09-15-2017 at 12:25 PM.
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  #77  
Old 09-15-2017, 12:39 PM
tom.j.fla tom.j.fla is offline
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As a rule voltages are +/- 20%. Service data at one time would have that noted in the info bar/box. All the best,Tom.J
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  #78  
Old 09-15-2017, 12:44 PM
FrankieKat FrankieKat is offline
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Quote:
Originally Posted by tom.j.fla View Post
As a rule voltages are +/- 20%. Service data at one time would have that noted in the info bar/box. All the best,Tom.J
Yeah, with no signal I'm getting pretty darn close to the schematic which says they were taken with no signal. With signal, many of those B+ voltages jump up 40% or more, but it sounds like that's actually fine because what was published wasn't measured under actual use conditions. The set works really darn well and so if this is in fact how it is supposed to run and I won't cook the tubes then I'm more than glad to move on from it!

Thanks!

FK

Last edited by FrankieKat; 09-15-2017 at 12:47 PM.
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  #79  
Old 09-15-2017, 01:13 PM
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Electronic M Electronic M is offline
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Generally speaking the only tubes you ought to be concerned with are power rectifier, H/V/Audio outputs and maybe a stray 6CG7/6FQ7 or 12AU7/12AX7....The rest are usually $1.50 bottles that only TV folks want (and unlike audiophiles/radio collectors) we're cheapskates.
I've got ~8 caddies full of mostly TV tubes in my work shop (a good portion used pulls in unknown condition), and I've been known to grab a used one smash it open and dissect it on the spot to explain how a tube works to an interested guest..."Hey Tom, might that have been a good tube worth keeping intact?"
ME:"who cares? It's a $1.50 6xx#....The visual aid/savings in explanation time we got out of it is worth it."
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  #80  
Old 09-15-2017, 01:35 PM
FrankieKat FrankieKat is offline
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Quote:
Originally Posted by Electronic M View Post
Generally speaking the only tubes you ought to be concerned with are power rectifier, H/V/Audio outputs and maybe a stray 6CG7/6FQ7 or 12AU7/12AX7....The rest are usually $1.50 bottles that only TV folks want (and unlike audiophiles/radio collectors) we're cheapskates.
I've got ~8 caddies full of mostly TV tubes in my work shop (a good portion used pulls in unknown condition), and I've been known to grab a used one smash it open and dissect it on the spot to explain how a tube works to an interested guest..."Hey Tom, might that have been a good tube worth keeping intact?"
ME:"who cares? It's a $1.50 6xx#....The visual aid/savings in explanation time we got out of it is worth it."
Ha ha, yeah! Well, I've bought so many tubes for troubleshooting that I've easily got enough for two more sets just like this, so I should be in good shape just in case. This whole voltage issue seems like a rookie misunderstanding on my part, so really a non-issue. The data sheets on the tubes in question (6CB6 and 6AN8) have a max plate voltage of 330V so running them at 160V instead of 125V doesn't sound like it would be any problem either way.

Otherwise my last issue here is that pesky picture glitching (and this), possible HV arcing noise that was bothering me a while ago went away, and now has come back which seems to happen after the set has warmed up about 5 mins or so. I did have to repair the grid cap wire on the horiz output tube because it had frayed at the point where it exited the cap and eventually broke off. Perhaps my solder job wasn't quite perfect enough. If not, will go back to dag. Will keep pluggin' away.

Also... let me just say huge thanks to everyone who helped out on this. I feel like this project a little bit of all kinds of things that could go wrong with an old, unrestored set and there's probably enough useful information in here to help many more restorers in the future.

Thanks everyone!

FK
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