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Philco 90 filament section on PT bad
#5

Well I am stumped.  I have removed the transformer completely.  I took the shields off, checked all the connections, one of the filament leads looked a little loose, so I resoldered it.  I put the transformer back together, checked all the ohms and unloaded voltages. I then took two 27 tubes, and four 24 tubes and wired the filaments up per the schematic with jumpers on my bench.  I wired them to the transformer and powered it up.  The filament voltage unloaded is 2.7v and with the 24&27 tubes hooked up ONLY, the voltage drops to 1.5v.  The current draw is 8amps.   Below is the voltages on the leads with and without the filaments of the 24 and 27 tubes hooked up.  

With 24&27 tubes hooked up only
Pri: 115vac.    .3 amp draw
Sec HV: 732vac
45 tube filament: 2.7vac
80 tube filament: 5.4vac
24&27 tube filament: 1.4vac

Without 24&27 tubes hooked up
Pri: 115vac   4.0ohms

Sec HV: 737vac.  237ohms
45 tube filament: 2.7vac.   .2 ohms
80 tube filament: 5.5vac.   .4 ohms
24&27 tube filament: 2.7vac.   .2ohms


Messages In This Thread
Philco 90 filament section on PT bad - by Skip - 04-02-2016, 01:08 PM
RE: Philco 90 filament section on PT bad - by Skip - 04-02-2016, 06:34 PM
RE: Philco 90 filament section on PT bad - by OZ4 - 04-03-2016, 11:02 AM



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