Hi Gary, Good deal on the recapping. Since the resistance on term 3 is so low it points directly to C548 or C551.
Regards, Larry On Tue, Sep 19, 2023 at 11:00 AM <[email protected]> wrote: > Larry, > > > > Thanks for pointing me to the 2 tutorials. They were very helpful. > > > > Unfortunately, my VTVM is 2,000 miles away and all I have is a VOM made by > Klein Tools. Initial reading was -3.5V at 3 and 4. After removing the > shorting bar, resistance at 3 was 350 ohms and on 4 was 1.65M ohms. I then > set out to recap the IF module and was able to get to all the caps except > for C545 and C548 which I couldn’t confidentially reach as the areas were > quite crowded with other wires or components. I will try again later. > > > > After changing most of the caps, the voltage now reads -0.17 (so worse) > and the resistance is 456 ohms at 3 (better) and 1.56M ohms on 4 (worse). > The meter now only deflects to 1 on the strong signal and up to 3 if I turn > the RF gain totally CW – however severe distortion of the sound results. > > > > Another nagging issue has raised its ugly head again. With the Line Meter > switch turned off and the line gain turned greater than 5, the line meter > deflects up to 40 with line gain at full CW and the amount of deflection > tracks the sound amplitude. > > > > I love a mystery but this one is getting daunting. I continue on. > > > > Regards, > > > > > > *From:* Larry H <[email protected]> > *Sent:* Friday, September 15, 2023 9:46 PM > *To:* [email protected] > *Cc:* [email protected] > *Subject:* Re: [R-390] Carrier Level Meter full deflection > > > > Hi Gary, Insufficient c/l meter deflection is usually caused by low gain > in the agc amp circuits or bad caps on the agc line. Try replacing V508 > and V509. The caps that usually cause this are C547, C548 and C551, but > there are many other problems that can cause it. See Charles Steinmetz > agc diagnosys document on our website and my agc diagnosys part 2, both in > the 'repair tutorials' section. > > > > Regards, Larry > > > > On Fri, Sep 15, 2023 at 9:24 AM <[email protected]> wrote: > > Larry, > > > > Thanks. Manfred Antar advised me privately to adjust the pot for the > carrier level meter. While that brought the meter to zero, it barely > deflects 30% even on the strongest local BCB stations. As well, on MGC, > the needle now goes negative. > > > > I will replace V506A and check the value of the plate resistor. > > > > Thanks for your input. > > > > > > *From:* Larry H <[email protected]> > *Sent:* Friday, September 15, 2023 12:17 AM > *To:* [email protected] > *Cc:* [email protected] > *Subject:* Re: [R-390] Carrier Level Meter full deflection > > > > Hi Gary, One possibility is that V506A is very weak or dead or its plate > resistor R549 is open or a very high value. > > > > Regards, Larry. > > > > On Thu, Sep 14, 2023 at 5:59 PM <[email protected]> wrote: > > Good evening, > > > > I am hoping for some help on this. On EAC S/N 3122, upon turning on the > radio, even without an antenna attached and not tuned to any signal, the > carrier level meter deflects fully in both AGC and MGC mode. The AGC > appears to be working because, on strong signals, the sound at the output > is > not as strong as on MGC. > > > > Any thoughts as to what may be causing this issue? > > > > Thanks in advance. > > > > ______________________________________________________________ > 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
