Naptha is a very effective grease and oil solvent. I used it to clean the gear-train in my R390.
Barry - N4BUQ > Hi > > As you do this, keep in mind that the “common wisdom” many decades ago was to > lube the geartrain like crazy. That was what a kid back in the 60’s likely > would be told to do. The lube used could be just about anything you can > imagine. Just as now kids got their information from a “range of sources” :) > :) > > Fortunately synthetic lubes did not often come up “way back then”. Many of > them > are nearly immune to various solvents and cleaning approaches. The idea that > they “never harden” may not have taken a 60 year sort of time period plus dust > into account. > > In some cases a pretty involved process could be involved to clean up after > some > kid from 60 years ago. > > Bob > >> On Oct 9, 2025, at 11:31 AM, Jim Whartenby via R-390 <[email protected]> >> wrote: >> >> Thanks Francesco! >> >> It takes several hours to do a proper cleaning of the geartrain to remove >> all of >> the old grease. I have used WD-40 as a solvent and Krud Kutter as a >> detergent >> since it seems that no one product can remove all of the grime. I have found >> that old spray bottles are great for applying the cleaning liquids. Rinse >> with >> water after each application, it will take several cycles to remove years of >> crud. An acid brush on a wood dowel is used to go deep into the geartrain. >> Finish with a final water rinse and then an alcohol rinse to release the >> water. Now a thin wood skewer is used to deposit a small drop of your >> favorite >> synthetic oil to each gear bearing which completes the process. Do not lube >> the gears themselves. The less lube you use the better, it will prevent dust >> and dirt from fouling the geartrain over the next 20 years! >> >> You will be very surprised how easy it is to now turn the two frequency >> knobs, I >> know I was. That "R-390 wrist" will be a thing of the past. Don't forget to >> dab some synthetic oil on the guide rollers and bearings found on the slug >> racks, they will need some lubrication too. >> Regards, >> Jim >> Logic: Method used to arrive at the wrong conclusion, with confidence. >> Murphy >> >> On Wednesday, October 8, 2025 at 01:59:57 AM CDT, Francesco Ledda >> <[email protected]> wrote: >> >> 👍 >> Sent from my iPhone >> >> On Oct 7, 2025, at 23:20, Jim Whartenby via R-390 <[email protected]> >> wrote: >> >> >> >> For the life of me, I don't understand why people grease the R-390 >> geartrain. >> The manual even says that it is better to not grease then to over grease. >> The >> group that knows the most about gear works, in general, are the clock >> collectors. Their advise is to sparingly oil pivot points and do nothing to >> the gear teeth. It will only collect dust and gum up the works, if you do. >> As >> for the R-390 or is it an R-390A? First, test all tubes, IRAN, second >> reseat >> all connectors, then test again. >> Regards, >> Jim >> >> Logic: Method used to arrive at the wrong conclusion, with confidence. >> Murphy >> >> On Tuesday, October 7, 2025 at 03:56:50 PM CDT, Adam Morehouse >> <[email protected]> wrote: >> >> Hey guys, >> >> I appreciate the pointers on my R-392, and now that it's buttoned up, it's >> time to work on my R-390. I only tested this briefly when I first got it, >> today I threw it up on the bench. Supposedly this was restored by Rick >> Mish, it is very clean (except the gear train, which has a lot of fresh >> grease...), and the front panel is pristine. >> >> It does pull stations, but the volume is extremely low in AGC mode, and >> gets slightly louder when placed into MGC. >> >> In MGC, with the BFO switched on, it plays at a normal (not super loud, but >> loud) volume. >> In AGC, with the BFO switched on, it hums, low volume audio. >> >> The limiter seems to have no effect, and varying the BFO doesn't do >> anything at all no matter AGC/MGC. >> >> I have Tom's solid state kit installed, and B+ at the AF deck test point is >> a steady 180.5vdc. >> >> I am going to dig out the TM's later on, I have them somewhere...but maybe >> somebody here can help point me in the right direction. >> >> Thanks! >> >> Adam K2AAM >> ______________________________________________________________ >> 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 >> >> ______________________________________________________________ >> 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 ______________________________________________________________ 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
