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Old 08-30-2010, 02:58 PM
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bandersen bandersen is offline
RCA 741PCS
 
Join Date: Mar 2009
Location: Chicago, IL
Posts: 8,826
I've tried everything I can think of and the HV just won't get up above 12kv. The voltages and waveforms on the 6CD6 seem reasonable.
  • swapping out the 6CD6 with a couple other 6CD6s
  • swapping out the 6W4 with other 6W4s, 6AX4s and 6AU4s
  • double checking all the associated components
  • swapping out the doorknob capacitor

On the positive side, the picture remained unchanged after any of those swaps. I even put some of the tubes that were originally in this set that tested weak or bad and it kept playing just fine. This must be one well designed set.

That leaves me with the flyback. It's tests OK with my EICO 944 and I've had the set playing for a couple hours so I think it is good, but maybe the Thordarson FLY-40 isn't a good substitute for this particular set ?

Here's a portion of the schematic with the resistance values and what I'm actually measuring. That 10.2 vs. 0.6 is the one that's got me concerned. Now that I think about it, that could explain why the horizontal size coil is getting hot. A larger resistance on the tap would mean a higher potential I would think. So that coil would have too much voltage across it.



Unfortunately, I don't have any replacements for it and struck out with Moyers. Does anyone have any of these flybacks ? Even if someone can just measure the resistance on a FLY-40 it would be helpful.

Motorola 24C792691
Thordarson FLY-40
Merit HVO-6

I do have these flys on hand. Maybe one of them is close enough to try
FLY-49
FLY-51
FLY-55
FLY-58
FLY-59
FLY-81
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Last edited by bandersen; 08-30-2010 at 04:31 PM.
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