07-13-2024, 03:06 PM
My $0.02:
+1 on the other comments, especially on pulling all the tubes and powering up. the transformer should run cold. If hot, then you are dealing with shorted or grounded coils.
First off, with all connected, does the radio play?
Secondly, what values did you use for the filter caps (C20, C21, C19)? They should be rather low (Preferably the values called out in the diagram but no more than 10 uF). if much more than 20 uF, the current will be too high. Working voltage should be at least 450V. Any lower and the cap may short.
If you can, break the circuit put a DVM set for 2Amp scale in in series between rectifier filament and junction of L7 and C21. Plug everything in. Per the RCA Receiving Tube Manual, max output current for a Type 80 rectifier with an expected output of 350V must be less than 125mA (0.125A on the 2A scale). Anything above that indicates excess current draw.
Power down, remove all tubes except the rectifier. If possible, place a second meter across C21, leaving the ammeter connected as above. Power up, monitoring voltage and shut down if the voltage at C21 exceeds its rating. Current draw caused by the filter caps, field coil, voltage divider (r11) should be about 30 mA or less.
Power down, and reinstall the output tubes. Current draw should increase, but no more 30 mA per tube of plate current. each of the other tubes (the 3 24As and the 27 should add no more than 5mA each.
Hope this helps.
+1 on the other comments, especially on pulling all the tubes and powering up. the transformer should run cold. If hot, then you are dealing with shorted or grounded coils.
First off, with all connected, does the radio play?
Secondly, what values did you use for the filter caps (C20, C21, C19)? They should be rather low (Preferably the values called out in the diagram but no more than 10 uF). if much more than 20 uF, the current will be too high. Working voltage should be at least 450V. Any lower and the cap may short.
If you can, break the circuit put a DVM set for 2Amp scale in in series between rectifier filament and junction of L7 and C21. Plug everything in. Per the RCA Receiving Tube Manual, max output current for a Type 80 rectifier with an expected output of 350V must be less than 125mA (0.125A on the 2A scale). Anything above that indicates excess current draw.
Power down, remove all tubes except the rectifier. If possible, place a second meter across C21, leaving the ammeter connected as above. Power up, monitoring voltage and shut down if the voltage at C21 exceeds its rating. Current draw caused by the filter caps, field coil, voltage divider (r11) should be about 30 mA or less.
Power down, and reinstall the output tubes. Current draw should increase, but no more 30 mA per tube of plate current. each of the other tubes (the 3 24As and the 27 should add no more than 5mA each.
Hope this helps.
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
Best Regards,
MrFixr55
