Philips PM6630 8 Digit Nixie Counter

[Spawn]

Trying to save a Nixie counter before it's Nixie tubes getting used in a Nixie clock.

Last week found a Philips counter with Nixie tubes on our local auction site and bid slightly over the asking price before the Nixie tube clock salvagers get their hands on it. Still it was not that expensive, I paid €60 including shipment.

Seller posted a picture in working condition measuring 200 MHz, but the unit was badly in dust.


Same Nixie counter but than 6 digit version is posted by @david77 here, there is one difference between the counters besides the digits, I will explain that below.

I am looking for some documentation for this unit, I asked already couple manual sellers here in the Netherlands, who are known to have documentation for this unit, but they didn't reply yet.

This is how I got the unit, covered in dust all over:




Inside:


Ovenized Oscillator:


The Oscillator is the other difference between 6 digit and 8 digit units, 6 digit unit does not have Ovenized one, the only article I could find of this unit was an old dutch electronics magazine from February 1970 and it basically explains where it's needed and some specs and explains about the difference, here is a screenshot of it (it is in Dutch)


Taken apart:


Checked all caps and only found 2 bad axial 16μF 16V caps, the caps on the unit are not easy to find, in our local electronics store I could find axial Vishay 15μF 63V caps, there is 5 of these capacitors on this unit, I replaced them all, the one in the picture below needed a lot of work to remove, so I decided to cut the leads and solder the new ones on there, otherwise I had to remove a lot of parts and wires to get behind, and I didn't want to risk that, other 3 caps where easily removable.
In total, there are 20 electrolytic capacitors in this unit, 5 are already replaced, so 15 to go. But the other capacitors measure good, so I will leave them for now til I got all of them, just weird values to find, but it still can be found I think, I just don't want to change the values much.


Here is the list of the capacitors which needs to be replaced:
2x   5000pF 250V (tested 500VDC) Type OPA-1-6-619x Safety Capacitor
2x   320µF 6.4V
5x   16µF 16V (replaced)
3x   4000µF 25V
2x   125µF 16V
2x    200µF 10V
   40µF 16V
   32µF 16V
   10µF 300V
   80µF 24V

Power supply board was dusty:


Cleaned the board, and you can see BY126 diodes created a lot of heat, maybe change these for other diodes which don't heat up this much? Which diodes will be good replacement here. BY126's are rated for 1.2A and 650V:


I cleaned a lot more, but don't have pictures of those yet, I will take some pictures when I put it back together.

[AVGresponding]

Very nice! And what a good price too!

If there's space, 1N5406 would run much cooler, they are quite a bit bigger though.

Good luck with the search for a manual, I'll ask a couple of nixie addicts I know that don't really come here any more.

[Spawn]

Very nice! And what a good price too!

If there's space, 1N5406 would run much cooler, they are quite a bit bigger though.

Thank you!
It is almost finished, I am going to post some pictures and write my experience about it.

[Spawn]

I worked on the counter again today, and it is almost finished, didn't put the front cover on yet, I wanted to make sure it is working correctly.

I have some minor issues, like little neon bulbs for MHz and kHz indications are not working, in the seller's pictures I can see the MHz indication, but it is not working right now, checked the voltage and 5V is there, so it looks like the bulbs are blown. I will replace every indication bulb with orange LED's soon as possible.

A quick test measuring 20MHz:

Just found out that my Function Generator is getting dodgy, the frequency is dropping little by little, first I thought it was because of the counter, but I got two other counters and those show the drop too.

Cleaned the front panel and the orange plexiglass:


Nixie tubes and its board also cleaned:




Put everything together, it is much cleaner now:


I don't have any frequency standard to check its oven oscillator, but my other two counters show both nicely 10MHz, so I think it is working as it should after 53+ years:





Other boards, also cleaned, just posting for reference if someone needs it:








The case is also cleaned, looks much better, I don't have pictures of it, but I will post those once I put everything together when the indicator bulbs are replaced.

 

[Zenith]

Try here for the manual

https://www.transistorforum.nl/forum/index.php?mode=thread&id=47777

It's also in the Netherlands and may be one of the ones you've tried.

[Spawn]

@Zenith, thanks for the heads-up, indeed I mailed those guys a couple of days ago, waiting for a reply.

[Spawn]

It is finished, other than some small scratches on its faceplate it looks pretty good.

Replaced the indicator neon bulbs with LED's, luckily one resistor was enough, cathode side is switched, and it has permanent +5VDC
I was afraid that orange LED's won’t be bright enough with the built-in diffuser, but it turned out great.



Both MHz and kHz indicators work now, when I cleaned the second layer faceplate I loosen the emblem badge, it is still attached secure, but I can't bother to remove the front plate to fix it right now, the caps on the knobs are not easy to remove without braking, one of the previous owners had a go with pliers to remove the knobs, but I could clean those marks up.