Quote:
Originally Posted by fox_rivers
Cool. Moving the ac line to 6 did the trick but now i only have one tube that illuminates which is the 6201 (12AT7). When i turn the lamp on the bulb glows dim and only the 6201 lights up but after a few seconds after the tube warms up the bulb suddenly brightens and the 6201 tube gets much brighter then its supposed to be. No other tubes light and this issue might explain why the 12AT7 that was originally in the set was dead.
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Strange behavior indeed. With only a 40W bulb in series with the set, I doubt the tubes would glow visibly at all, although they may get hot enough to function, which would explain the sudden brightening of your bulb. However, the only thing I can think of that would cause a filament to get brighter when DC flows is a defective tube, or perhaps a filament-cathode short at the socket. Dirt in the socket could be an issue as well.
For now it might be useful to disable the DC supply so as to sort out any filament supply issues (If you want to see the tubes glow, you will need a bigger light bulb). The 6201 actally has two filaments, connected in //. Check that pins 4&5 are connected together.
BTW,if you are using the cap based ballast, it will take longer for the tubes to 'light up' in an obvious way, and they will begin to function before fully lit.