Hello All, Last night I was able to slowly bring the set up on my variac and - it works! I was able to tune in a few stations, and everything appears to function, even the antenna relay! I had to replace one dead 6082 tube in the regular circuit. B+ measures 171.1 volts steadily at the J601 test point on the side of the chassis, with basically no fluctuation.
Is 171 volts this too low for the B+? According to the manual it should be 180 volts. Could this be caused by weaker rectifier or VR tubes? What is next? My thought was to replace the 8 47ohm resistors - 4 each in the power supply and audio modules. Unfortunately I do not have a reliable tube tester. Thanks, -Alex On Fri, Feb 6, 2026 at 12:15 AM Alex Hopper <[email protected]> wrote: > Jacques - I didn’t want to be the one to say it, but thank you! > Interestingly, most of the key differences are in the power supply/power > management! > -Alex > > Jacques Fortin <[email protected]> schrieb am Fr. 6. Feb. 2026 um > 00:13: > >> Hi John, >> Ahem... The Alex concerns were about a R-390/URR, not a R-390A/URR... >> Despite the two versions share the same fit, form and function, there is >> significant differences between the two. >> >> 73, Jacques, VE2JFE in Montreal >> >> Hi Alex - Good questionsI have attached two documents that will help you >> in understanding how these power supply filtering caps are electrically >> located in the power supply circuit. I do hope you have acquired the >> knowledge to read a schematic, if not this can be acquired. Depending upon >> the age and condition of the existing filter caps, I would treat them as >> suspect and likely needing to be replaced, unless evidence from performance >> validation shows otherwise. While they might "operate", residual AC ripple >> is not to your receivers advantage. You will need to try to understand how >> a power supply filter capacitor failure mode will likely result in >> regarding what else you might then need to repair. The Y2K manual contains >> a number of options exist regarding these filter capacitors. If you power >> these up outside of the receiver, give them a good session with slowly >> increasing voltage and slowly increase current demand into a load such as a >> 25 watt stove oven light bulb initially. Monitor output with a scope if >> you have one available. The peak current is at first on cold inrush, once >> warmed up the current is about ~~1.3 or so amps if I remember correctly. >> Try to operate the receiver at 115 volts rather than the standard 126 volts >> now on the US mains voltage using a variac and if available a 1:1 isolation >> transformer. Good luck \VR\John >> >> ______________________________________________________________ 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
