Philips PM6630 Nixie Counter

[david77]

Once again I could not resist to buy some piece of testgear from ebay. It has nixies, it does not work and it is disgusting. Perfect!

I wanted a nixie counter for some time but I was not willing to spend the kind of money HP or Systron Nixie counters usually fetch. So this Philips counter immediately caught my eye. From the seller's description and pictures it looked very much like a heap of crap. I could see through this veneer of dust, corrosion and mildew and recognised the beauty within.

Then it arrived.



To the sellers credit he did not sweet talk its appearance in any way. It arrived exactly as filthy as advertised. Nice.

The outside is just a little dusty. The inside is where the filth really lives.



Mainly the power supply area is drenched in some sort of sticky brown goo and some funky chrystaline growths. I have no idea what that is.







At first I thought I got a very heavy smokers gear but it does not smell of cigarettes at all and the dirt is just on the inside and then just in the back of the device. The front part of the insides is relatively clean. Maybe a cap exploded and spewed its guts everywhere?
Possible these axial blue Philips caps are always suspect. Judging by the brown goo inside it must have been a rather major event.

Then there are these six green diodes on the PSU board. They look like something ate away at their epoxy (?) casing and the top bracket of the transformer mount is heavily corroded. It is a mystery. Maybe something was spilled into the machine? I don't think so the outer metallwork of the case looks clean.

EDIT: Nope it does not. Something corrosive and sticky has been spilled into it. Mystery solved.

Anyway I really did not want to power the counter up while the PSU was in this state. Construction is quite nice, most boards are plugged int card edge connectors. I removed the PSU board and set about cleaning it with a brush and isopropyl. No luck. Drastic measures had to be taken. The board got a bath in warm water and dish soap. That and an old toothbrush removed all that weird dirt.
That revealed how suspect the blue Philips caps really looked. The rubber seals on some of them were bulging and cracking. The funny thing is they all measure fine. I decided to change the small axials but will keep the big 4000µf 25V cans for now.

So that seems to throw the exploding cap theory out the window.

After cleaning and recapping the power supply I powered it up on the variac & dim bulb tester. The counter came straight back to life and even started counting once I applied full 230V mains. I do not have a service manual or any sort of schematics but the supply voltages are printed on the underside of the PSU board. The four voltages were all spot on.

The only other thing I had to fix so far was the status/range display next to the nixie display. This used some tiny 5V bulbs to back light the different range displays (MHz, kHz, µs, ms, s, Error). These bulbs were all dead apart from one. I replaced them with yellow 3mm LED's and a suitable resistor.

[unknownparticle]

Nice find!  Shame about the condition but a nice instrument regardless.  I have a thing for Philips test gear as I once worked for them in the 70's, at that time the build quality was superb. It deteriorated in the 80's when it all went plastic, so everything snaps when taking apart for servicing.

[david77]

She's cleaning up nicely. And yes, there is practically zero plastic on this beast. All steel and aluminium.

Maybe one of the EEVblog forum members from the Netherlands has a manual for this counter? I've been struggling to get the display board out for the last hour as I need to replace one of the decimal point light bulbs. I think I need to take the front panel off but it's putting up a good fight.

I need to take the front panel off anyway for cleaning.

[david77]

I just had a closer look at the 10MHz frequency reference board and found the most beautiful 10MHz XTAL I've ever seen.



The case is made from glas. It lives in this ugly piece of styrofoam.