Bob cracking me up and as always your comments are on target. Get the polarity right. Good news if you get it backwards you instantly know it. Boy the old keep it the same is a tough question. I fall into the camp of I want it to reliably work with stability. I have also fixed much older gear like 1929 radios and at that age the caps and resistors do change an very magical ways. So I am not a purest. I like the fact that modern caps are generally smaller so they will fit into the space available. My belief is that the smaller space means ultimately a shorter life. Instead of 40-80 years maybe 20-30. Hmmmm not to worried about that, it will be someone else issue. Most likely the junk man.
But if anything I hope he has a good time with his magical 115BR. If I do ever see one at the hamfest after reading this thread I am pretty sure I will stay clear of it. Who needs the noise. Happy holidays to everyone. Regards Paul WB8TSL On Sat, Dec 24, 2016 at 11:03 AM, Bob Camp <kb...@n1k.org> wrote: > Hi > > Modern tantalum caps get a bad rap. When you dig into the data, most of it > relates to > the “bad old tantalums”. What you have in these devices *are* the “bad old > tantalums”. > When they go, they can make both a massive mess and a real stink. > > The idea of keeping things “as built” in vintage gear is never a bad > thought. A lot of fine > old gear has been trashed by “improvements” (some done by me …) over the > years. > In the case of wet slug tantalums (the proper name for these beasts), not > a real good idea. Replacing them with modern solid slug tantalum caps is a > good idea. > They have some “interesting” features in timing circuits, so replacing > tantalum with > tantalum is a good idea. Make sure you get the polarity right :) > > Bob > > > On Dec 23, 2016, at 8:50 PM, paul swed <paulsw...@gmail.com> wrote: > > > > Looks like you have great advice. But I will add if the tantalums show > the > > corrosion do not fire it up. Unless you like smoke and other damage. A > good > > way to extend the time you will spend getting it going and cleaning up > the > > acid all over everything. Lots-O-fun. > > Good luck and I have always heard the mechanics were the challenge. No > real > > experience. > > Regards > > Paul > > WB8TSL > > > > On Fri, Dec 23, 2016 at 6:24 PM, Hugh Blemings <h...@blemings.org> > wrote: > > > >> Hiya, > >> > >> My thanks for the various replies including to Luciano for the 115BR > >> manual and Chuck for the timely advice about old caps! > >> > >> I'll take a put at summarising the various replies and my own > observations > >> now I've the 115BR Manual and the 115CR unit itself - any errors in same > >> mine alone; > >> > >> The 115CR appears to be a slightly later device - it's 2RU rather than > 3RU > >> and uses plug in PCBs rather than point to point/tag strip style > >> construction. > >> > >> Based on a quick glance at the 115BR service manual and the 115CR unit > >> itself, I'd venture they are electrically and mechanically very similar, > >> possibly identical. > >> > >> The 115CR seems to have hard wired DC input polarity relative to ground > >> wheras the the BR is switchable. The 115CR doesn't have a meter or as > many > >> frequency output options. > >> > >> Maintenance wise; > >> > >> * Divider circuits need to be manually started using internal switches, > >> the unit has built in rack rails to support easy access. Similarly the > >> motor must be manually started. > >> > >> * Many of the silver can (physically larger) axial capacitors on the > PCBs > >> in my unit show signs of corrosion - this presumably the acid leaking > out > >> of the tantalum caps as Chuck alluded to. > >> > >> * One correspondent suggested replacing the caps right from the word go, > >> another to go for broke and turn it on - not sure which way I'll go yet > ;) > >> > >> * The mechanical odometer style display needs care not to bind up/jam. > >> Attention to lubrication/grease for the motor and other bearings seems > >> prudent. Don't force any of the mechanical components. > >> > >> * Looks like I can get a paper manual here > http://www.etestmanuals.com/Se > >> arch.aspx?Search=115CR - I think this will be my next step. > >> > >> I'll close for now with this quote from Chuck which may dash my plans to > >> have it on permanent operating display; > >> > >> "These clocks are not a lot of fun to live with. They sing along > >> quite loudly at 1KHz." > >> > >> ...so might not be ideal in the otherwise quiet lounge room after all :) > >> > >> Thanks again all for the input so far, will report further progress > when I > >> return to the device in the new year after a house move :) > >> > >> Cheers, > >> Hugh > >> > >> > >> > >> _______________________________________________ > >> time-nuts mailing list -- time-nuts@febo.com > >> To unsubscribe, go to https://www.febo.com/cgi-bin/m > >> ailman/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. > _______________________________________________ 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.
