12-24-2015, 12:03 AM
I am wondering if anyone has checked the ohms on a Philco Model 20 power transformer using a DMM? I am interested in the reading between the CT, pin 6 of the power transformer to pins 1 and 2 (2.5VAC). Reading without any tubes or the pilot lamp installed. I understand that you should read .1 to .2 ohms, on either side, however my DMM reads 0.F on the auto range and on the manual range 0F. meaning 0 ohms. From pin 1 to pin 2, I measure .3 ohm. It is as if the CT is missing. I have checked and re soldered the terminals of the transformer and nothing changed.
I am checking this because of a 60 HZ hum that can only be eliminated by grounding the grid of the 27 audio tube. ALL COMPONENTS HAVE EITHER BEEN REPLACED OR SUBSTITUTED EXCEPT THE POWER TRANSFORMER. I am questioning the transformer because after turning it on and off a number of time, while testing, with or without tubes, I get a quick ARC sound out of the power transformer. I found out grounding the chassis to the house ground, blows the circuit breaker.
I am checking this because of a 60 HZ hum that can only be eliminated by grounding the grid of the 27 audio tube. ALL COMPONENTS HAVE EITHER BEEN REPLACED OR SUBSTITUTED EXCEPT THE POWER TRANSFORMER. I am questioning the transformer because after turning it on and off a number of time, while testing, with or without tubes, I get a quick ARC sound out of the power transformer. I found out grounding the chassis to the house ground, blows the circuit breaker.
