[R-390] R390 (non-a) low audio

[Kevin McGrath]

I have recently acquired an R390 non-A -- in addition to the R390A I bought last month. (Egads! does this mean I am hooked!?).

 I have set about getting the R390 working again and have made progress. So far I have replaced the low voltage rectifier (CR108) to get the antenna relay working; fixed a loose connection on the Line Audio switch to get the Line Level meter working and fixed the low B+ voltage (was only 135v) by replacing C608 in the AF unit.

At this point it is receiving signals, but the audio level is low even with the Local Gain set at 10. So I am about to do the voltage and resistance checks in the AF deck.

I have a R390 newbie question regarding the voltage checks at the tube sockets. Are they done with the associated tubes still in place? If so how does one get at the pins...use a tube extender? Or are they taken with the associated tube removed and probed from the top of the empty socket?


I am using a 8 ohm speaker with a 1000:8 ohm transformer from radio shack. Sure, it's not the proper 600:8 ohms but I wouldn't think the mismatch would result in low audio levels when running the Local Gain wide open.

Any other tips for investigating low audio are appreciated.

Kev