HP 5065A Rubidium Standard Repair/Restauration

[pquadrat]

Hi Everyone,

I got a HP 5065A  Rubidium Vapor Frequency Standard yesterday, for free. Got it from a calicration lab, which calibrated my EDC MV116 voltage standard, and they wanted to throw this 5065A away.

It was not used for some time, hat some dust on it, but no corrosion or mechanical damage.

I will follow this thread https://www.eevblog.com/forum/metrology/inspecting-aligning-and-testing-an-hp-5065a-rubidium/, replace all 100uF capacitors, and do the checks.

It is a late production unit, S/N2740A0xxxx, already with the 10811-60109 Crystal Oscillator.Best, I could not spot any previous repairs, all seems to be original. Corrosion by the 100uF caps is very limited.

Some pitures attached:


-Peter

[KE5FX]

Nice save!  It's a good idea to replace all of the dry tantalum axial electrolytics -- meaning any that are sealed with rubber rather than glass -- not just the 100 uF parts.  Pay particular attention to the 20 uF parts on A11. 

Most or all of the wet (glass-sealed) axial caps will be OK, but they should still have their ESR checked.

[edpalmer42]

If the capacitors have caused any damage to the traces, inspect the board *very* carefully.  On my 5065A one of the traces was so completely destroyed that I didn't realize that there had been a trace there in the first place!

It also wouldn't hurt to check the main power supply capacitors.  On mine, they rotted away completely a few years after I got the unit.  Corby (5065guru) said that it was an unusual occurance, but it's easy to test.

Corby knows more about these things than the designers so he'll be a huge source of info.

If you haven't already done so, search the forum for all references to 5065A.  There's lots of good info and documents right here.

Ed

[pquadrat]

Thanks for all these little details. Of cource I did read Corbys thread, and I will follow his procedure.

The 20uF caps are already normal electrolytics, not tantaliums, but original, so HP changed this in later models.

With the corrosion, I have a very late unit, so there were 10 years less time to corrode. Overall, nothing looks to bad.

Now I am just cleaning everything inside very carefully, should look new inside then.

Peter