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-   -   Halolight flyback? (http://www.videokarma.org/showthread.php?t=269671)

bgadow 12-23-2017 09:50 PM

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.

bgadow 12-25-2017 10:06 PM

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!

miniman82 01-02-2018 09:12 AM

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!

miniman82 01-07-2018 10:07 AM

Mark spotted a Merit HVO-124 replacement on eBay and I bought it, hope it’s good for only $12. lol

miniman82 01-11-2018 09:14 PM

1 Attachment(s)
:banana:


Raster is full and bright, gonna put it back together and enjoy it for a while.


http://videokarma.org/attachment.php...7&d=1515726725

Crist Rigott 01-11-2018 10:51 PM

I'm happy for ya!


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