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The fly-171 looks closest, even shows the RFC on the plate lead of the HOT.
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Watching this thread; I have my Halolight on the bench now, no HV, no B-boost, damper is red plating. Hmmm...
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Your oscillator probably isn’t running, got a scope?
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Is it recapped?
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To get the damper red plating, you would almost have to have drive on the HO tube. It still doesn't hurt to scope the drive on the HO. There must be a problem in the boost circuit. It's been ages since I had to trouble shoot this circuit. :scratch2: |
Sounds like a hard short-to-ground somewhere on the cathode side of the damper.
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There are some paper caps left but I think only in the audio circuit. I haven't hooked up the scope yet but today I dug out my Sencore sweep circuit troubleshooter. HO tube cathode current looked normal & adding drive from the troubleshooter had no effect, though I did notice the damper wasn't glowing like before. Using the troubleshooter's yoke substitution test didn't help; when using its flyback test it points to either a bad fly or something in the load circuit, according to the instructions. Further clues: when I started, the fuse in the yoke circuit was blown. Also, I have replaced the damper, rectifier & HO tube with NOS. Outwardly the fly looks normal. I have also tried hooking it up to my Sel-Son crt subber, which I figured would eliminate the yoke from suspicion. No variance.
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Success! Now, the rest of the story...
After replacing the filters & vertical/horizontal caps I had decided to power the set up for the first time. Prior to that I happened to peer into the HV cage & noticed that the HO tube had gone to air. This set, per Sams, was built with either a 6CD6 or 6BQ6-mine had the former. No problem-I have thousands of tubes, mostly NOS, & 10' away I'd find a stack of these. But wait...I don't have a single one! How could that be? I coulda sworn...so out comes my trusty Riders tube substitution guide which says 6DN6 or 6EX6. Well, I'm POSITIVE I have some of each...nope! Not a one! I really didn't want to wait for one to be shipped in so I grabbed a thicker tube sub book off the shelf, one published by TAB books. Yep, here it is-says a 6DQ5 also works. Well, that I had-5 NOS ones right at hand. Fast forward. Later on Christmas Eve, after my wife settled in for her "long winter's nap", I pulled out "GE Essential Characteristics" to study the base diagrams of 6CD6 vs 6DQ5-maybe there's something that's blank on one & a tie point on the other? Well, it turns out they're totally different! Not a sub at all (unless, maybe, if you re-wired the socket-in which case I might as well re-wire to a 6BQ6). Lousy misprint! No wonder the circuit didn't work! I went to the attic & dug out a box of surplus tubes. I knew for fact that there wouldn't be a 6CD6 in there because, well, I put those tubes there & it just didn't belong. But, there it was, pretty as you please, a NOS Rogers of all things. 10 minutes later & I was staring at a bright raster! I did some further tweaking today, swapping out some tubes & buttoning up some things. I should have it all back together later in the week. Thanks, guys, as your advice really did work to put me on the right track & helped me learn a thing or two. Now, back to your reguarly scheduled program...uh, thread! |
Lol, glad it worked out. This Halolight has a 6DN6 in it right now, funny you should mention. Side note, I sent a request to that Ersc place because supposedly they had a good fly on the shelf. Never heard anything back...
Search continues! |
Mark spotted a Merit HVO-124 replacement on eBay and I bought it, hope it’s good for only $12. lol
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Raster is full and bright, gonna put it back together and enjoy it for a while. http://videokarma.org/attachment.php...7&d=1515726725 |
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