Phillips PM3217 50MHz Oscilloscope Repair No.2

[dazz1]

Hi
Some time ago I wrote up the re-capping of a PM3217 scope.  Thanks the the generosity of Tautech, I now have a PM3217 No.2.
The No.2 old scope is also ex-Navy.  It is much younger than the No.1 PM3217.   Chip dates indicate 1986 vintage.  I also suspect No.2 has spent most of its time aboard a ship.   The blue filter on the CRT looks like new.   It would have spent most of its time locked up in an air-conditioned, temperature & humidity controlled, filtered air environment.    The perfect environment for preserving test equipment.  It would have seen relatively little use compared to a scope sitting on a lap bench.

Since leaving the service, it has been stored in a shed, and it appears that it may have gained some cosmetic blemishes.  Inside the scope, it is immaculate.  No dust, mold or corrosion.

[dazz1]

Hi
So before applying power, I did some routine inspections, specifically including the Rifa capacitor.  Well known for being small explosive devices that release lots of nasty magic smoke.
One of the problems with capacitors is that they can fail with no visible sign that they are no good.  I really need a ESR meter to do in-circuit testing of caps.  If I had an ESR meter, I would have used it on the Rifa cap to measure if it was still OK or not.

As a precaution, I did change the Rifa cap for a nice yellow one that is not made by Rifa.

[dazz1]

Hi
So after taking a close look at all of the old school analog goodness, I applied power.
At first, nothing happened, then something did.
It worked.

[dazz1]

Hi
At present I am soak testing it to flush out all of the old electrons that have had nothing to do for too many years.
The tube is sharp and bright.  There is no buzzing or other warning signs. 
Initial twiddling of the knobs and switches indicate some are a little scratchy but that is already clearing.

A quick play with the delayed time base hints at a problem, but I need to do some more functional testing to confirm if there is a fault.  Even if there is a fault, I know the parts will be available to fix it.  That is the really nice thing about this stuff is that it is almost eternal.

[dazz1]

Hi
Well that was disappointing.  A quick spray with some alcohol and the delayed time base features started working again, just as I was breaking out the long and detailed Service Manual.

All of the scratchy switches and knobs now work like they just left the factory.  Thirty six years later, this scope is still doing the job it was built for.