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Looking for service manual Philips PM3253 (or PM3251)

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Buzzz

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I am looking for a service manual of a Philips oscilloscope, type PM3253. Have been searching the internet for quite some time, but I haven't found anything yet via the regular websites.

A manual of Philips' PM3251 could possibly work as well, since it appears to be a more basic version of the same oscilloscope.
My PM3253 is having some issues with the analog storage function, a feature which the PM3251 has as well (but which the PM3250 and PM3252 don't have).

I hope someone can help me out!
 

Buzzz

New Member
Thanks for your reply. I have read the documents, the pm3252 doc is the closest to what I need. Unfortunately it doesn't contain the storage circuit. The others do give me an idea of how Philips made this work, but it would be great to have the exact schematic.
Does anyone by any chance have this specific part of the doc of either the pm3253 or pm3251?
 

rumpfy

Active Member
Buzz,
I dont know the Philips PM 3253. My guess is that your cro has a 'storage tube'.
If so, the following may help.
I have a Tektronix 564 with the storage tube. I understand that the original design concept was pioneered by Hughes Corp of the USA.
There was a post about the TEK 564 cro in this forum. See what information you can get off this forum about the storage part of the 564.
The storage circuit uses 'Flood Guns' to 'illuminate the screen. The level of energy supplied by the flood guns is just below the level required to make the screen light up. When the normal writing beam illuminates the screen, the screen is pumped up in energy and gives off light and there are secondary electrons generated off the screen. The so called storage effect is a very slowly decaying light output from the screen. there are adjustments for the basic 'flooding' level'. I dont believe the storage systems are significantly different.
 

Buzzz

New Member
rumpfy, thanks for your reply. I managed to get the whole documentation complete from pm3250 thru pm3253, where the storage unit is described in the pm3251's manual.
The storage part is like you describe, using floodguns.

I've found that the high voltage cascade is not functioning properly, this appears to be a common problem in Philips oscilloscopes. I've ordered some parts to build a new cascade unit, I'm still waiting for the parts to arrive...
 
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