I did something similar- momentary contact of +15V supply with one of the other pins- might have been the +5 Vin, or another signal. The 75ACT240 became very hot. I ordered a replacement 75ACT240 part, swapped it in, and the unit seems to work fine now. Note this is the 0.3" wide device, DigiKey p/n 74ACT240SC-ND. Confusingly, that part in 20-pin SOIC is made in two different body widths: 0.209" / 5.3 mm and 0.295" / 7.5 mm.
This photo shows the board with the smoked chip removed (U503 at upper left), before I installed the replacement https://picasaweb.google.com/lh/photo/mF9WSGlEQjA8MqHhbPOJRdMTjNZETYmyPJy0liipFm0?feat=directlink -john > -------Original Message------- > From: EB4APL <eb4...@cembreros.jazztel.es> > To: time-nuts@febo.com > Subject: Re: [time-nuts] FE-5680A performance > Sent: 05 Jan '12 11:37 > > I found it, I used the +15 V of my triple output supply to power the > pin 4, +5 V input. A 75ACT240 popped up and who knows the health of the > other things. > > Wish me luck, > Ignacio, EB4APL > > > El 05/01/2012 18:54, EB4APL wrote: > > > > I agree, I've seen it in a Tek 7623A with the storage on, it is quite > > difficult without it. > > > > Regards, > > Ignacio, EB4APL > > > > PD. Just trying to verify this I made some error and let the magic > > smoke leave the unit. It is still smelling ... > > > > > > > > _______________________________________________ > 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.