Hi Alex, C101 is the main filter for the regulated 180V supply. C103 is the local filtering cap. for the audio output stages. Look at the schematics ! Remember also that the voltage regulator/audio module cannot work properly if the receiver is not completely assembled. Test all the tubes before trying to power the radio: an open filament in the serial stings for the filaments power (all running from the 25.2V) can create a lot of preventable problems. About C101 and C103: if you see no oil leakage around the seals, they should still be OK. I once measured the leakage on the ones from my R-390: 2 or 3 µA at full rated voltage. But remember the age they have... they could eventually fail, one day or another. Check also all the 47 ohms resistors in the rectifier tubes cathodes, and the ones in the cathodes of the regulator tubes (6082) also. Replace with new 5W rated parts if they are "off" by more than 10%.
Good luck and let us know the results. 73, Jacques, VE2JFE in Montreal Hi Folks, Later this week I am going to slowly start up an R-390/URR that I recently purchased. After careful visual inspection and removal of several of the modules, I am confident enough to start it slowly on a variac. My question is, what provides the typical 'filtering' of the rectified DC voltage? Is this C101 (the large rectangular metal box capacitor next to the power supply)? What does the other large, cylindrical capacitor C103 do? Are these capacitors failure prone? Should I expect the need to replace them? Thanks, -Alex ______________________________________________________________ R-390 mailing list Home: http://mailman.qth.net/mailman/listinfo/r-390 Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ R-390 mailing list Home: http://mailman.qth.net/mailman/listinfo/r-390 Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
