Problem on a PULSAR Date/Command

[dmc12]

Hi everybody,
My Pulsar Date/Command model 3100 was working perfectly (I was wearing it for several days) until when without any action on the button the display came on.
Impossible to stop the display ,so removing the batteries was the only solution to stop the display.
I have put the batteries back but the problem remain the same.
Apparently the display show the date.
Any ideas ? or a solution to repair it ?
Many thanks in advance.
[/b]

[J Thomas]

[dmc12]

Thanks a lot for your answer.
Something I did not mentioned is that I have tried with the module out of the case , same problem.
So no button problem but as you say a reed switch problem.

[J Thomas]

[retroleds]

Jeff:
Great job on helping out here - seriously. If his date is stuck on, it is the date reed(possibly the internal circuitry) that is bad, as the date function takes precedent over the time function in all the Pulsar modules.. That is: if the time reed is closed(time displayed) and then(with time still closed/displayed) you close the date reed, date will be displayed. If date is closed first, time reed has no function. Conversely, a Pulsar where time display stays on is never falling victim to a bad date reed for that issue (albiet, that reed could have it's own problem).

[dmc12]

Thank you for your help.
I will test it later (nearly 1AM in France now,so time to sleep)

[J Thomas]

[retroleds]

Thanks Ed.
I was over my head here. I really appreciate that you stepped in and explained the peculiarities of how the two switches interact.

Hey, I knew you aren't like one of those Pulsar fanatics , so that wasn't necessarily something that would just jump out of your memory banks. You, ReWolf and a couple others run circles around me on the electronics,....I'm just a [mostly] self-taught technician. You work on enough of those things, it becomes an automatic, mental flowchart for the diagnosis. Personally, I would just snip the reed out(right next to the tube) and see if it stops(using some tweezers to turn it on/off a few times to check for consistent function....figuring I'm going to be replacing the reed anyway if it work, or be stumped if it isn't. Even if it mysteriously unstuck itself, would you really want to leave that reed in? But, that's just me.

[Old Tom]

Two things;-

1. DVMs- if you are using one on an ohms range check the voltage it is applying across the probes, more than 3 volts and you risk frying an input junction. Many modern DVMs have up to 9 volts across the probes and can create a problem rather than reveal one! I use an old analog 50K/volt meter with a single 1.5 volt battery in it so nice & safe.

2. Stuck reeds;- Reed switches slowly but surely become magnetised (it used to be a big problem in old style 1960s reed/transistor telephone exchanges) and get stuck closed. You can demagnetise them with a tape head demagnetiser (if you can find one!- I have a tiny battery powered TDK compact cassette type that works well) provided you place a shorting clip across the reed switch terminals to prevent stray currents cooking something (needless to say module should be out of case or you will demagnetise the buttons). A whole lot easier than pulling a reed!

[rewolf]

...
1. DVMs- if you are using one on an ohms range check the voltage it is applying across the probes, more than 3 volts and you risk frying an input junction. Many modern DVMs have up to 9 volts across the probes and can create a problem rather than reveal one!..

Good point. Any half-decent DVM shouldn't do this, but with the cheap stuff sold for a few bucks at the DIY store you never know...

[retroleds]

You can demagnetise them with a tape head demagnetiser (if you can find one!- I have a tiny battery powered TDK compact cassette type that works well) provided you place a shorting clip across the reed switch terminals to prevent stray currents cooking something (needless to say module should be out of case or you will demagnetise the buttons). A whole lot easier than pulling a reed!

Well, I guess that is a "your mileage may vary" situation....I find replacing a reed takes me only a minute or two(setting reeds are a bit more time consuming, due to positioning). Demagnitizers and stray electrons sound scary to me...

[rewolf]

...Demagnitizers and stray electrons sound scary to me...

Looking at your avatar picture I wouldn't have guessed that

[retroleds]

...Demagnitizers and stray electrons sound scary to me...

Looking at your avatar picture I wouldn't have guessed that

Even that robot got zapped occasionally. "Danger, Will Robinson! Danger!"


More "robot-isms"
"My micromechanism thanks you, my computer tapes thank you, and I thank you."
"I compute it to be an ionic directional probe searching for receiving outlets."
....last but not least..

"That does not compute."

[dmc12]

Hi,
Did the test using an analog DVM (1,5V) with the same reading on both reed switches.
Readings are different if you change the polarity contrary to what
J Thomas say.
Anyway if both reed switches shows the same readings I assume that the date one is not malfunctioning as I thought previously.
New ideas are welcomed
Thanks

[retroleds]

Hi,
New ideas are welcomed
Thanks

Snip out the reed, right next to the tube, on the chance you have failed somehow in the test procedure. If it stops running, you just need a new reed switch. If it keeps running, end of game(other than rinsing the module or blowing out the main chip with some low pressure canned air....

Please refer to the Pulsar Jeweler's Manuel, 2nd Edition., 5th link down in the Digital Workbench section(HOme Page) regarding the cleaning.

The reed replacement is a lot less likely to damage a [possibly] functional movement then the cleaning.