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 Post subject: Philips PM-3200 scope question (trigger issue)
PostPosted: May Sun 01, 2016 2:00 am 
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Joined: Jan Thu 01, 1970 12:00 am
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Location: Warner Robins, GA
I have one I just purchased today for $45

It functions real good for the most part except the trigger does not work.

I downloaded the schematics and board layouts from Radiomuseum. First thing I noticed is that the schematics have waveforms shown at a circuit point where a waveform should be present, but in my brief scan of the schematics I did not notice if it had voltages listed.The second thing I noticed is the PC board layout does have voltages listed.

This scope could have been also ran on a battery.

Initially I thought the CRT was weak or the voltages were low as the display looked a bit dimmer than most scopes, until I realized it has P2 or equivalent phosphor which isn't as bright, but is slower decaying. Great I thought. I now have a solid state scope I can use to view low frequency waveforms with. I can use other scopes I have, but the P1 phosphor decays quicker making low frequency waveforms hard to see on the CRT.

I love how Philips did the switches. All front panel toggle switches operate a rod which actuates a slide switch right on the PC board. The two rotary switches are unlike any I've ever seen. The wafers are similar to a standard rotary switch, but the wafers are much larger and have some components and traces on them with the contacts on the PC board. What they did by doing that was to eliminate switch wiring and all the potential problems wring can cause.

Three things that are lacking on this scope. Verniers for the V/div and time/div switches and also no variable trigger control, but had it been necessary or of benefit to have those controls they would have been included.

Any idea what the issue with the trigger circuit is?

I may start taking voltage measurements Monday afternoon if I get time to do so.

Should I go ahead and replace all the electrolytic caps or is this one where the electrolytic caps are usually found to be still good?


Last edited by Tube Radio on May Thu 05, 2016 11:18 am, edited 1 time in total.

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 Post subject: Re: Philips PM-3200 scope question
PostPosted: May Sun 01, 2016 11:38 am 
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Joined: Jul Wed 22, 2009 2:07 pm
Posts: 960
Hi Tube Radio,

Nice little scope!

I would not replace all the electrolytics wholesale just yet!
Check them with an ESR-meter if you suspect them, and only replace the bad ones.

If you do not have an ESR-meter, build one! I built the 99-cent tester:
http://members.ozemail.com.au/~bobpar/99_Cent_ESR.pdf
I built the version with the 555-timer and for a fixed frequency (about 70kHz).
It is one of the most useful test equipment that I have!

As for the scope not triggering, any chance that the trigger source is not set for "Internal"?

In the following thread there are number of pointers to PM-3200 manuals, you do not have to suffer through the RM download!
http://www.electro-tech-online.com/threads/pm3200-sematic-request.16151/

Good luck, Peter


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 Post subject: Re: Philips PM-3200 scope question
PostPosted: May Sun 01, 2016 1:10 pm 
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Joined: Jan Thu 01, 1970 12:00 am
Posts: 22026
Location: Warner Robins, GA
Thanks for the info.

I did check and the trigger was set for internal. Noticed the switches were a little touchy so I cleaned them just in case that was the issue, but it didn't fix the problem.

do notice that if I actuate one of the switches (forget which one) it may trigger briefly then go back to having the problem.

I'll look at the other links later today. If they have more info and a full one page schematic then that will be better.

It's nice that the pc board layout has the voltages on it as I don't have to look at the schematic and try to find that component on the pc board and wonder if I'm at the right spot for a given voltage measurement.


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 Post subject: Re: Philips PM-3200 scope question
PostPosted: May Tue 03, 2016 1:26 am 
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Location: Warner Robins, GA
Looks like I may have found a potential issue.

Measured the main power supply voltage after noticing some of the other power supply voltages were off and here's what I got.

23.27Vdc for 25.34Vac input to bridge.

26.5Vdc for 26Vac input to bridge.

Bridge rectifier does get warm.

Seems to me like it's an indication that the bridge rectifier may be going bad.

Connecting an external supply proved interesting as if something isn't exactly right the scope's power supply will not run at all.

EDIT:

Triggering problem solved :D :D :D

I found a bridge rectifier from a defunct piece of equipment and substituted it for the original rectifier.

The scope now triggers properly on all but the HF reject position.

orbanp, I looked at that link and the only manual was in a foreign language.

All I really need is the calibration procedure.


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 Post subject: Re: Philips PM-3200 scope question
PostPosted: May Tue 03, 2016 6:25 pm 
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Joined: Oct Fri 16, 2009 10:10 pm
Posts: 504
Location: Bergen NH The Netherlands
Maybe you can give Google translate a try?
Dutch to English.
Jard N.

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If You Ain't Dutch, You Ain't Much


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 Post subject: Re: Philips PM-3200 scope question
PostPosted: May Wed 04, 2016 1:13 am 
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Joined: Jan Thu 01, 1970 12:00 am
Posts: 22026
Location: Warner Robins, GA
Maybe so, but the manual is all in pictures. Will Google Translate work with that?


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 Post subject: Re: Philips PM-3200 scope question
PostPosted: May Wed 04, 2016 6:32 pm 
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Joined: Oct Fri 16, 2009 10:10 pm
Posts: 504
Location: Bergen NH The Netherlands
I never had to use Google Translate,because we had to learn English,French and German at school.
But after 55 year all the French is forgotten and the German tourists keep that language a bit alive.
(Visiting the Dutch North sea beach and that silly cheese market in nearby town.
Attachment:
kaasmarktjpeg.jpeg
kaasmarktjpeg.jpeg [ 12.98 KiB | Viewed 2969 times ]

And this forum exercises my English ( but sorry for the readers)

But:Google claims it must be easy ,if one can believe this site:
http://www.investintech.com/resources/b ... guage.html
Maybe other forum members have more experience,because many had this problem with Grundig,Telefunken,Greatz and all the other German service manuals.
I wish you succes,you have the bad luck that with later models all the Philips manuals came in four main languages.
Jard N.

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If You Ain't Dutch, You Ain't Much


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 Post subject: Re: Philips PM-3200 scope question (trigger issue)
PostPosted: May Thu 05, 2016 11:30 am 
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Joined: Jan Thu 01, 1970 12:00 am
Posts: 22026
Location: Warner Robins, GA
Looks like I have a trigger issue.

Decided to do a test using a sinewave from 400-20Hz and I got some displays that look like what one may see if there was no triggering at all, yet the scope did seem to be triggered on the waveform.

Also I can see the trace varying ever so slightly in intensity and also moving about very slightly.


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 Post subject: Re: Philips PM-3200 scope question (trigger issue)
PostPosted: Aug Thu 26, 2021 4:42 pm 
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Joined: Jan Thu 01, 1970 12:00 am
Posts: 22026
Location: Warner Robins, GA
I had been putting off replacing a broken trimpot in this scope for 2-3 years as I have other scopes, but I decided to replace it.

So not having the scope at work and knowing the approximate location of the trimpot I set out to find a manual so I could look it up.

I finally found an English manual here.

https://www.lost-manuals.com/manufactur ... s/PM3200_X


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 Post subject: Re: Philips PM-3200 scope question (trigger issue)
PostPosted: Jun Thu 23, 2022 9:28 am 
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Joined: Jun Thu 23, 2022 9:25 am
Posts: 2
Hello,
I own a PM3200 that works fine except triggering, which is not working at all (tried internal only).
What is the bridge rectifier and trimming pot references I should look at in priority ?
Thank you.


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 Post subject: Re: Philips PM-3200 scope question (trigger issue)
PostPosted: Jun Thu 23, 2022 9:55 am 
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Joined: Jun Thu 23, 2022 9:25 am
Posts: 2
Tube Radio wrote:
I had been putting off replacing a broken trimpot in this scope for 2-3 years as I have other scopes, but I decided to replace it.

So not having the scope at work and knowing the approximate location of the trimpot I set out to find a manual so I could look it up.


Hello,
Finally, which bridge and trimpot did you replace ?
Thank you.


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 Post subject: Re: Philips PM-3200 scope question (trigger issue)
PostPosted: Jun Thu 23, 2022 1:01 pm 
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Joined: Jan Thu 01, 1970 12:00 am
Posts: 22026
Location: Warner Robins, GA
The bridge rectifier is the one in the power supply.

The trimpot I haven't actually replaced yet, but it affects the horizontal and was replaced because it fell apart.


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