I need help on a PUlsar-Pulse

[retroleds]

Customer sent me a Pulsar Pulse - I'll admit, I have never worked on one before. The display had completely came off the chip - I reglued with silver based epoxy and gently clamped overnight - ok, good, the dispay workes marvelous. But the watch has a bad habit of going into a 00 mode for no apparent reason. :(
I've gone over every bit of the circuit under the microscope...all looks good. And it keeps perfect time.
Thoughts, suggestions, please.

[gjlelec]

i had a Longines that used to do exactly the same thing, it would run for a few days then revert to zeros. I guessed what happened was that something would momentarily short the battery, the voltage would drop off- and it would revert to zeros- as if you had just installed newbatteries.Whilst it worked it kept perfect time- the only other anomaly was that it would eat a set of batteries in a couple of weeks

[Old Tom]

Is the display just the two left hand digits?- I was wondering if this might be the result of a slight misalignment of the LED & phototransistor in the pulse sensor giving rise to a "phantom" finger sense by this pair causing the watch to flip over to pulse mode (and showing zero pulse because no finger is present). Or maybe one of your work lamps is triggering the phototransistor (fluorescent lights are the worst offender). Must admit to never having had one of these so preceding is just speculation.

[bruce wegmann]

Tom might be on to something. How well does the pulse-rate part of the watch work; you didn't mention whether this section was functioning. The time and PRM circuits are completely separate. These are notorious for not working right...I suspect that Time Computer had problems just getting them out the door in presentable condition. They apparently didn't make many and didn't sell many, probably for just that reason. This was tricky, new, cutting-edge technology, and the company didn't last long enough to work all the bugs out before closing their doors forever, so now we collectors get to deal with them.

[retroleds]

I decided to "punt" and throw in a new oscillator crystal just on chance it was screwing with the works. The time and date functions work marvelously, but the pulse circuit doesn't do squat. I consider it a success when I can get from a dropped off display like this

to this.


It was my first time with one of these - darn interesting circuit, the batteries are hooked up in series for a total of 6 volts(tapped off at 3 volts for the clock portion), which is brought from the case, back into the circuit via a contact below the sensor, running straight away into the the infra-red light(even now infra-red lights and sensors really suck up juice). Well, I played with it for 3-4 hours and charged the guy an even $100, :? I'm glad to hear I'm not the only one who hadn't seen much of these. It was a nice NOS piece with EVERYTING imaginable in the very nice box(almost identical to a Pulsar Cal. box.)

Punt(just one definition): "to do something without proper preparation or planning by making it up on the spot".

Thanks fore all the suggestions guys 8)