Just a follow-up for others that may run into this someday I took apart the PRS10 and disassembled the lamp assembly, Not easy..
I discovered that the MRF134 in there was still functional but that there was a second short that was preventing oscillation, this looked to be due to solder reflowing slightly from a joint to a chip cap had been soldered with an excess amount of solder in manufacturing I removed this, tested the fet which was still ok but would be a real bear to replace. I then tested each discreet component (ceramic caps with LC meter, resistors etc) I put the lamp assy and the PRS 10 back together Now looking though the hole provided I can see that after a short warmup the lmap now does light (it didn't previously) however the unit no longer locks to Rb I have shelved the PRS10 and rebuilt my reference around a Trimble thunderbolt. Perhaps at a later date I'll have another go at it thanks for all the help On Wed, 2011-02-16 at 22:37 +0000, Brendan Minish wrote: > Interestingly it was not your normal tin whisker (I have seen a few of > those, just..) it was a substantial one that had grown out from the > stack of 2 Ceramic caps in series with the coil to the RF choke in > series with the DC supply to the lamp housing. > > It might even have been a solder blob left over from production but it > looked quite crystalline. > It's a bit ugly in the lamp assy because the heat and strong RF field > made a bit of a mess of insulation on the RFC and the heater leads but > everything else seems ok > > I'll try and locate an MRF134 and see how I get on, certainly worth the > price and time by the sounds of it. > > thanks for all the help and encouragement > > On 16/02/2011 22:14, Pete Lancashire wrote: > > http://nepp.nasa.gov/whisker/ > > > > I've fixed two cell phones for friends and I have a very nice MP3 > > player I got for $1. > > > > Each was fixed with a stiff brush with a combination of compressed air > > (outside) and > > a vac inside. > > > > -pete > > > > PS if you do the air thing don't forget about static use a ionizer. > > > > > > > > On Wed, Feb 16, 2011 at 1:58 PM, Bob Camp<li...@rtty.us> wrote: > >> Hi > >> > >> Real solder has lead in it to eliminate tin whiskers. > >> > >> We're going to see a lot of stuff die in the coming years from these little > >> critters. > >> > >> Bob > >> > >> -----Original Message----- > >> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On > >> Behalf Of Magnus Danielson > >> Sent: Wednesday, February 16, 2011 4:55 PM > >> To: time-nuts@febo.com > >> Subject: Re: [time-nuts] SRS PRS10 problem > >> > >> On 02/16/2011 10:31 PM, paul swed wrote: > >>> Well a couple answers. > >>> If those are RB whiskers try the heat gun at 300 degrees on it for 15 > >>> minutes. As Magnus suggests and I just tried for the first time. It > >> actually > >>> worked and I recovered the rb lamp. > >> > >> While the heat gun on the Rb lamp is a nice trick, the whiskers most > >> likely is nothing but traditional tin whiskers. A bit of re-soldering to > >> remove bad metal and replacement of burned transistor is where I would > >> start. > >> > >> Cheers, > >> Magnus > >> > >> _______________________________________________ > >> time-nuts mailing list -- time-nuts@febo.com > >> To unsubscribe, go to > >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >> and follow the instructions there. > >> > >> > >> _______________________________________________ > >> time-nuts mailing list -- time-nuts@febo.com > >> To unsubscribe, go to > >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >> and follow the instructions there. > >> > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > -- 73 Brendan EI6IZ _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.