[time-nuts] HP5065A revival project, progress report

Magnus Danielson magnus at rubidium.dyndns.org
Mon Oct 3 17:54:54 EDT 2011

Fellow time-nuts,

I wanted to bring you an update on the HP5065A revival project.

I have three units, unit A, B and C.

For unit A I have been able to achieve lock, unit B had a PSU failure 
and so did unit C. The PSU of unit A is about to fail, but I will fix it up.

I have now done some work on the A15 board of unit B, repaired traces 
and replaced 4 caps. It still provides a heavy load which makes the +20V 
supply "duck" to 8,70V, as it goes into current limiting. Interestingly 
enough this is limited to the PSU board itself. To test this theory I 
borrowed the A15 board from the unit A into unit B, and using my 
experience of trimming up unit A I was able to get unit B to lock up and 
even lit the Continous Operation lamp.

So, now I have both unit A and unit B locking up for me, but I will have 
to work more on the A15 assembly for unit B in order to get them 
operational at the same time. However, it will be much more rewarding to 
work on that board now that I know that it is about the only thing I 
need to fix, and I've already come a bit down the road on that one.

Unit C also has the A15 board failure, but it failed even more 
spectacular, so I will need to replace the zener diodes as the acid took 
one of the zener diode legs with it... :P
First degree cleanup has been started.

I will also need to replace caps on A15 on unit A, as they are about to 
fail. However, running shorter batches should be fine for the moment, 
especially as I cab down and get additional convection.

Anyway, it is quite rewarding right now. I just couldn't avoid sharing 
some of the progress. Hope it doesn't add too much to the noise here.


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