Bob Thanks for the pictures and clues. I have a bad lucent on a hp3801. It was just 1 of the supplies so I adapted an alternate switcher and it works just fine. That said there is hope I can go back in and fix it and also if need be the ones on the KS units I have. I have sensed there is a flake-y unit on one of them. Regards Paul WB8TSL
On Sat, Apr 11, 2015 at 12:52 AM, Chuck Harris <[email protected]> wrote: > That is almost a carbon copy description of how I fixed a > similar module in my Ball/Efratom MGPS unit on my GPSRb > unit. > > An oven set to 140C is your friend when doing jobs like > this. > > The guys that make these modules are trying to make them > as small as possible, so they always use tantalum capacitors, > and run them very close to their ratings... in this case, it > was 18V on a 20V cap. > > This particular module had +/- 15V, and +5V on board. I have > never seen so many individual switching power supplies stuffed > into a single module... They were all little 5 terminal IC's, > with each running at whatever frequency it felt like... > > -Chuck Harris > > > > > Bob Stewart wrote: > >> This is just a brief report, not a how-to. >> >> I got a KS_24361 with a bad Lucent power module. Having nothing to lose >> I thought >> I'd see if it came apart. After unsoldering it from the motherboard, I >> found the >> usual potting compound. Fortunately, the compound was only loosely >> attached to >> the board in the brick and was easy to pick off. After that, I used a >> pair of >> needle-nose pliers to work the board out of the casing. In spite of the >> pic >> below, I first gently pried up on the corners, in succession, until the >> corners >> released. Then I worked my way toward the middle, until the board came >> out. Be >> aware that there are two small inductors on the top side of the board >> that have >> metal covers that will probably stay in the potting compound. Just leave >> them >> there. When you push it all back together the covers will go back on the >> inductors. >> >> http://evoria.net/AE6RV/KS/OpenUp.jpg One corner of the brick was pretty >> hot while >> I had it on, so I figured there was a shorted component. As it turned >> out, it was >> a 15uF tantalum cap with a big brown spot on it. >> >> http://evoria.net/AE6RV/KS/BadCap.jpg Here's the cap removed from the >> board at the >> upper left. http://evoria.net/AE6RV/KS/CapRemoved.jpg >> >> So, ordered the cap, put it on the board, then just pushed the pins into >> the >> motherboard for testing. I didn't even bother soldering it. >> http://evoria.net/AE6RV/KS/Testing.jpg Tests were good, so I stuffed the >> board >> back into the casing, and soldered it all back on the motherboard. I >> didn't >> bother repotting the bottom surface of the board. I attached the >> repaired KS to >> my good REF-0, and it's now working. Bob - AE6RV >> >> _______________________________________________ time-nuts mailing list -- >> [email protected] To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the >> instructions there. >> >> _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
