Yes the last word is accurate for lightning and TBolts or anything else. The super hot chips a clue to trouble. The other thing on a hit is that months later stuff starts acting up. Seven hits over 30 years and yes I ground stuff. Regards Paul WB8TSL
On Wed, May 11, 2016 at 8:48 PM, Scott Newell <[email protected]> wrote: > At 03:19 PM 3/31/2016, Ryan Stasel wrote: > > I do know 74AC04’s are horribly prone to ESD damage… replaced more than a >> few when working on older bench multimeters. >> >> You may need to get in there and probe a bit. In my case, my bad RS232 >> driver was drawing about 350mA and getting VERY hot, VERY fast. >> >> Good luck, and let us know! >> > > Finally replaced the RS232 interface chip and the 'AC04 PPS buffer. Still > dead. > > Probing around, it looks like the UART output is stuck in a break > condition (232 out is at +9V, and the input to the driver is near ground). > The 32kHz CPU rock, the 3.684 MHz clock, and the 10 MHz OCXO are all > singing. No PPS visible anywhere on the 'AC04. I do see bus activity on the > SRAM. The CPU is getting very hot--it's the hottest chip on the board, > nearly as hot as the OCXO. There is a ~60 kHz clock visible on the temp > sensor. I couldn't find anything that looked like the GPS bitstream--maybe > the CPU has to program the synth first? > > I guess I can strip the OCXO off the board--it's a good Trimble 37265 from > the TAPR group buy. > > Crap. > > > -- > newell N5TNL > > _______________________________________________ > 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.
