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38-116 Code 125 Tube Heater Circuit Issue
#6

I re-checked voltages.  Still 723 vac between the plate sockets of the rectifier.  Voltage at cap 120 is still low.  279 vdc from + to chassis ground and 331 vdc from + to - terminal on original cap.  The voltage diagram says first should be 315 vdc and second should be 385 vdc.  The voltage on cap 123A is now -54 vdc; but, the voltage on cap 123 is only 318 vdc (should be 370).  Voltages on caps 70, 70A, and 70B are just slightly low; 245 vdc vs 260; 76 vdc vs 90; and 218 vdc vs 225.  The plate on the 6J5 driver tube still reads low at 54 vdc.

I checked resistance between rectifier sockets 7 and 8.  Supposed to be less than .1 ohm but I get much higher readings, from 3 to 10 ohms, depending on how the probes are positioned.  Also checked the vac between those sockets and got 5 vac.

By the way, I have the input voltage to the radio set at 115 vac.

Added edit: I very much appreciate the time you've spent educating and helping me with this radio.  I thinking about just setting it aside for now.  There is a much nicer 38-116 that will be sold at an auction near me this coming Saturday.  The cabinet is in much better condition than mine and the chassis has all its tube shields which means it hasn't been hacked to accept metal tubes.  


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RE: 38-116 Code 125 Tube Heater Circuit Issue - by LarryFS - 09-21-2019, 01:43 PM



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