Ed, The LED clock is relatively simple. It is power, ground, and a 1 PPS pulse. There are also some controls if the AC power goes out and the unit goes to battery back up. Then you have to push the button on the front to see the time.
The chip is a 5313. There are also at least two versions of the LED clock, one with three PC boards and one with two. I have a number of these in 5061A's and one in a 5065A, all of which are the 'two PC board' variety. The schematics are available in the 5061A manual and, possibly, in the 5065A manual. I had a 'dead' clock in one of my 5061A's that turned out to be U1 (5313) on the A2 board and was able to find the chip from one of those 'findchipsnow' type websites from maybe 'Area 51'?? There was a minimum order of $100 and the chips were $25 each, I think. Anyway, I bought 4 (or whatever), removed the dead chip, installed a socket, inserted the 'new' chip and all was well. I have some spares if needed for what I paid plus postage, if you need one. I'll have to go back and verify what I paid for the chips but I think I am close. While seemingly outrageous in price, it was easier than spending two weeks 'rebuilding' the clock. When encountering a dead clock, the likely culprit is dead electrolytic capacitors and/or a dead Q3 on the A1 Regulator Board, a 2N2905A. Other than the one example of a dead 5313, all the other failures have been the capacitors and Q3. Good luck, Joe -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of ed breya Sent: Tuesday, September 27, 2011 12:55 PM To: [email protected] Subject: [time-nuts] HP5065A digital clock info I am restarting an old project to transplant my HP Z3801A guts into a 5065A carcass, and now designing the power system. I'd like to keep the original LED clock function, but with all new power and interface. I traced out the circuit partially a few years ago, and am going by the notes I made back then. The clock IC is a 28 pin DIP, marked with the National Semiconductor logo, and only the code "025B." I assume it is a standard clock IC of the era, probably PMOS. Does anyone know the true part number? I have never seen a 5065A schematic or parts list. The HP part number may help if it can be cross-referenced. I have looked at data on a number of National and other clock ICs from back then, and saw none that seem to match what's in there. Ed _______________________________________________ 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.
