Products > Test Equipment
Philips PM6650 Counter/timer with dead A input
sbprojects:
It is indeed a panaplex display. The instrument is in a rather beautiful condition. It has no latches. So you can see it count, then the display freezes until it has to count again. Real vintage. The 6652 is far too modern.
Gyro:
Yes, their older ones are lovely. All discrete logic, no fading EPROMs to worry about. You can change the display counting behaviour with the Memory button irrc.
My PM6622...
https://www.eevblog.com/forum/reviews/lets-see-your-nixie-tube-equipment/?action=dlattach;attach=244012;image
sbprojects:
Thanks Gyro. Indeed the Memory button changes the counting behaviour. I didn't RTFM, because don't have the FM. My memory key has some trouble latching, needs some cleaning I guess.
And the input amplifier of the PM6622 looks a bit similar to what I've seen on the PM6650. At least it features a dual JFET, which is my main suspect.
Gyro:
You're welcome. Yes a little TLC works wonders.
A couple of quick and simple checks. Make sure the voltage little Out(?) terminal at adjacent to the trigger level knob varies sensibly when you adjust the knob, on both voltage ranges (and knob pulled and not). Also check that you actually have electrical connection between the BNC connector and the PCB (you should be able to read 1M resistance on the BNCs in DC mode without having to take the lid off). It wouldn't be the first time...
Don't rule out the possibility of switch contact issues (or no-FM trouble) with the input trigger related push buttons either. Worth checking before assuming that it's the JFET.
Lastly, don't forget that the counter has a check function which should at least exercise the trigger logic (though probably not the analogue front-ends).
P.S. Looking at the picture, the PM6622/24/25 manual should be helpful for most functions, even if the control layout isn't identical.
WirelessESD:
Hello I own a physical copy of the PM6650 manuals and have recently gone through the effort to digital scan the service and user manual.
You can find them on:
- https://museum.dantalion.nl/item/philips-pm6650-counter-user-manual
- https://museum.dantalion.nl/item/philips-pm6650-counter-service-manual
As well as archive.org directly using:
- https://archive.org/details/philips-pm6650-counter-operating-manual
- https://archive.org/details/philips-pm6650-service-manual
Appreciate if you also check out the rest of my museum ;)
Kind regards
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