Philips PM 3217 Oscilloscope - horizontal sweep intermittent

[K3z]

Hi,

I recently picked up one of these PM3217 fairly cheap locally as I have been wanting to get into EE.

This is my first scope and I don't really have a lot of knowledge generally. I am decently experienced with soldering, but not really understanding the inner workings and reasons behind it.

Anyway, the scope seemed to be working fine but once I got it home it started to have a problem where the traces are like 1cm wide in the middle of the display:

.

If I leave it on for a while, it will intermittently switch between working properly (with the beam moving left to right like it should) and then getting stuck in the middle again.

Does anyone have an idea as to what might be wrong? Is this a setting somewhere or perhaps some failing caps? Like I said I am fairly comfortable doing some soldering if needed to get it working again, but my diagnostic game is not strong.

Thanks

[SMdude]

Does bumping it make it play up / come good?
Or working the switches?

If you can bump it and have an effect, I would be looking at dry solders, especially in places that might get a little bit warm.
Anything that looks suspect, add solder, suck it up and resolder with fresh solder.
I would be inclined to bump around the boards a bit (screw driver handle) while it is running, but be careful cause it can bite you!

If working the switches brings it back, then you might have a dirty switch.

[anachrocomputer]

A nice old analog scope!  There\s a thread about it here:

https://www.eevblog.com/forum/testgear/view-on-philips-pm3217-50mhz-analog-oscilloscope/

And some other info in PDF files:

http://wiki.makespace.org/images/3/3d/Philips_PM3217_50MHz_Oscilloscope_Manual.pdf

Someone did a restoration on one of these scopes at the UK Vintage Radio Forum:

https://www.vintage-radio.net/forum/showthread.php?t=127596

The scope has an X MAGN control, also labelled PULL FOR X10. This must be linked to the timebase circuit, and will be worth checking. If the switch is flaky (as old switches often are), it could affect the timebase width.

Oh, and whereabouts in Britain are you? If you're anywhere near Bristol, consider visiting the Bristol Hackspace open evening one Thursday (from 7pm), where you'll find analog scope enthusiasts!

[K3z]

Hey thanks for the responses. Strangely, I noticed that the trace became more consistent the longer it was running, so I left it on for a couple hours and it seems to be working okay now even if I shut it off for a while. Not sure if this is something to be concerned about.

Many thanks for all the files and information, I will probably look into doing a fairly thorough refurb of this thing when I get the time. Clean all the switches, replace electrolytic caps and reflow the joints.

I am a couple hours from Bristol but I will definitely consider checking out the Hackspace if I get a chance, looks fun!

[bd139]

Remove the back panel from it ASAP. There’s a gold RIFA capacitor hiding behind a fibreglass screen on the voltage selector switch. Snip it out. The buggers explode and do some serious damage. This happened to my PM3217.

Trace problems on those are usually the power supply capacitors being shot. The blue Philips ones are getting on a bit now. Worth replacing them as well as if they go short they burn the windings out on the switching transformer secondaries which are irreplaceable.

Switches are also a problem on them. The latching changeover ones will benefit from a squirt of switch cleaner (I use WD40 branded switch cleaner (not normal WD40!) from Halfords).

These are my favourite scopes after the Tek 455 series. Really high quality bits of kit with good triggers.