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  #46  
Old 11-04-2017, 07:27 PM
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  #47  
Old 11-04-2017, 10:22 PM
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Congrats. Not too many of those left making light on the front end...
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  #48  
Old 11-05-2017, 12:14 PM
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Congrats. Not too many of those left making light on the front end...
Thanks! I hope to see your 21-CT-55 lighting up shortly... that's a set I'm truly envious of. Superior wideband chroma demod without the pain in the ass 15GP22 to deal with. That's a winner in my book.

I've determined that I don't have vertical sweep at all, the focus was just messed up. I can now get it sharply focused down to three unconverged lines (not that I'll run it like that). All three guns are fine; using the built in gun killing switches on the back shows normal results.

I've also determined why I don't have vertical deflection; the cathode connection on the 6AH4 is either open, or the tube is stone dead. It doesn't deflect the meter on my Hickok at all, even at 12.6 volts on the filament. I've ordered a new Westinghouse branded 6AH4, and also a 6BL7 for the vertical convergence and color killer. The 6BL7 is very weak. I'll see if that helps. I'd like to be know that the vertical is semi-operational before the set goes to Nick. I'll feel better knowing that all of the major parts are working correctly.
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  #49  
Old 11-05-2017, 12:43 PM
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Patience and you will get there. Good sign on the CRT.
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Last edited by etype2; 11-08-2017 at 03:40 PM. Reason: Remove unrelated comment.
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  #50  
Old 11-06-2017, 01:13 PM
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I am gathering up tubes to send along with the chassis when Nick restores it. The cascode RF amp is listed as either a 6BQ7A or a 6BZ7. I know they're interchangeable, but I'd like to know which should give a better noise factor. I plan on taking the set up to Sault Ste. Marie to DX some Canadian analog repeaters once it's working properly. I just have to see it working the way it would have in 1954 with a proper antenna etc.

The other, more troublesome, tubes are in the chroma. The service manual lists the R-Y and B-Y demod tubes as being either type 6AS6 or 6DB6. It also specifically states to only replace with the type shipped with the reciever. I have no clue what was in the set originally. Am I correct in assuming that one could stick either tube type in, perform an alignment of the chroma sub chassis, and be fine?

Any guidance is much appreciated...
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  #51  
Old 11-06-2017, 01:36 PM
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Originally Posted by benman94 View Post
I am gathering up tubes to send along with the chassis when Nick restores it. The cascode RF amp is listed as either a 6BQ7A or a 6BZ7. I know they're interchangeable, but I'd like to know which should give a better noise factor. I plan on taking the set up to Sault Ste. Marie to DX some Canadian analog repeaters once it's working properly. I just have to see it working the way it would have in 1954 with a proper antenna etc.

The other, more troublesome, tubes are in the chroma. The service manual lists the R-Y and B-Y demod tubes as being either type 6AS6 or 6DB6. It also specifically states to only replace with the type shipped with the reciever. I have no clue what was in the set originally. Am I correct in assuming that one could stick either tube type in, perform an alignment of the chroma sub chassis, and be fine?

Any guidance is much appreciated...
Ben,

I assume you've checked the cabinet tube chart if available. And also the Sams which I'm including here. Hope this helps.

-Steve D.
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Last edited by Steve D.; 04-04-2018 at 04:24 PM.
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  #52  
Old 11-06-2017, 01:41 PM
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Ben,

I assume you've checked the cabinet tube chart if available. And also the Sams which I'm including here. Hope this helps.

-Steve D.
The tube chart in the cabinet lists both types unfortunately, with neither scratched out. It also lists 3A3 or 1B3 for the HV rectifiers, but has 1B3 scratched out.

I'll look at the Sam's closer. Thanks Steve.
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  #53  
Old 11-06-2017, 02:07 PM
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The tube chart in the cabinet lists both types unfortunately, with neither scratched out. It also lists 3A3 or 1B3 for the HV rectifiers, but has 1B3 scratched out.

I'll look at the Sam's closer. Thanks Steve.
Ben, Sorry. Should have included the Sams top view tube chart. Notice they have the 1B3 & the 6AS6 listed as well as the 6BZ7. Who knows?

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Last edited by Steve D.; 04-04-2018 at 04:24 PM.
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  #54  
Old 11-06-2017, 02:30 PM
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IIRC, Sam's bought the sets they used for the Photofacts, either that or they were lent them, in any case. I'm going to assume the my set was built with the more common 6AS6, just as the Sam's set apparently had. My set does have 3A3s where the Sam's shows 1B3s... who the hell knows?

I'll try both the 6BZ7 and the 6BQ7A; they are slightly different according to the GE manual, but close enough to assume that either will work.
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  #55  
Old 11-06-2017, 02:43 PM
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One quick way to find which tube is better would be to check introduction dates...Often the newer interchangeable type was an improved version of the older one.
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  #56  
Old 11-06-2017, 05:25 PM
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One quick way to find which tube is better would be to check introduction dates...Often the newer interchangeable type was an improved version of the older one.
This was actually a great idea Tom. I looked up the 6BQ7, 6BQ7A, and 6BZ7 intro dates. The 6BQ7 came first with a mu of 35 per section. Then came the 6BZ7 with a mu of 38 and lower noise. RCA promptly retooled the 6BQ7A to match the noise figure of the 6BZ7 and upped the mu of each section to 39. The 6BK7 and 6DJ8 can also sub in parallel heater circuits, both offering an improvement over the 6BZ7/6BQ7A in a cascode arrangement. Then along came the Nuvistor and the rest is history.
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  #57  
Old 11-06-2017, 06:07 PM
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Regarding 6DB6 vs. 6AS6, since the schematic says either and doesn't show any alternative circuitry, I think it's safe to assume that the only differences are small ones that might skew the alignment a bit, as you said.
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  #58  
Old 11-09-2017, 10:40 AM
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Getting so much better all the time!

Reminds me of that Beatles tune... "...getting so much better all the time!"

Vertical is back, and the vertical and horizontal dynamic convergence circuits are semi-operational. I may end up starting the recap myself instead of waiting to send it to Nick. It's a good portion of the way there already and I've only replaced a couple of caps.

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  #59  
Old 11-09-2017, 11:26 AM
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"WOW-ZERS!" LOOK AT ALL THE COLOR! Getting better all the time, is right! So enjoy the progress reports, this set is going to display an excellent picture, when all is said and done!
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  #60  
Old 11-09-2017, 12:22 PM
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We second that. Hopeing for the best.
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