Author Topic: Philips PM3295 350 MHz Oscilloscope Guts  (Read 4932 times)

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Offline Cigarsnob

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Philips PM3295 350 MHz Oscilloscope Guts
« on: July 16, 2013, 09:22:43 pm »
Was at the monthly Electronic Flea Market over the weekend in the Silicon Valley and found a Philips PM3295 350 MHz 2-channel oscilloscope for $20. Couldn't really argue with that and couldn't help but take the chance, as I didn't know if it would work or not. Didn't know Philips did scopes back in the day. Does anyone have any history of them and or experience in using them/thoughts etc etc?

Of course the damn thing didn't work when I got home and I eventually smelt something wrong. Undressed the little thing and was impressed and annoyed with what was there. I'm a young engineer and have only played with the insides of HP scopes (Nice and open and easily accessible) and this Philips guy is all crammed and covered with plates/modules/etc etc....Anyway...I noticed on the power supply board had a blown cap on one of its modules. See the figure below. I figure I'll look for a respectable replacement, pop it in, and take it from there. The scope looks pretty and I would love to get it back on the air.

I do have the manual: http://www.ko4bb.com/Manuals/Philips/Philips_PM3295_Service_Manual.pdf

Any other links would by highly appreciated.






Busted 0.22uF Cap on the power supply board



Zoomed-in shot of 0.22uF blown cap on the power supply board


 

JuanPC

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Re: Philips PM3295 350 MHz Oscilloscope Guts
« Reply #1 on: July 16, 2013, 10:52:02 pm »
Bear in mind that capacitors inside the instrument can hold their charge even if the instrument has been separated from all voltage sources.
WARNING: Any interruption of the protective earth conductor inside
or outside the instrument, or disconnection of the protective earth terminal, is likely to make the instrument dangerous. Intentional interruption is prohibited.


has 21kV.
 

Offline casinada

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Re: Philips PM3295 350 MHz Oscilloscope Guts
« Reply #2 on: July 16, 2013, 11:04:22 pm »
All those caps look like bulging. Try to measure all of them for shorts but since you have to take the board apart may as well replace all the paper caps (plastic rectangular looking) and the electrolytic caps. Try to use good quality capacitors and make sure that match or better the original specifications. I recapped a Tektronix 2465B a couple of months ago  :-+ . Good luck with the project and be careful with the high voltages present in the guts of the scope.  :)
 


Offline Cigarsnob

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Re: Philips PM3295 350 MHz Oscilloscope Guts
« Reply #4 on: July 16, 2013, 11:59:41 pm »
All those caps look like bulging. Try to measure all of them for shorts but since you have to take the board apart may as well replace all the paper caps (plastic rectangular looking) and the electrolytic caps. Try to use good quality capacitors and make sure that match or better the original specifications. I recapped a Tektronix 2465B a couple of months ago  :-+ . Good luck with the project and be careful with the high voltages present in the guts of the scope.  :)

I'm making a list now of caps that I should replaced  ;D
 


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