[time-nuts] HP-5372A operation with no battery

[Magnus Danielson]

Hi Lester,

On 2020-07-29 16:22, Lester Veenstra wrote:
> Hi Magnus:
>   You are, of course right;  For a ham, the video board repair was trivial. I now have three working boards, one reinstalled in my HP-5372A.
While I do not found it natural that I am right, I am happy that my
hunch was correct. Really great to head
> So, of course, now I have the out of cal message, traceable to the RAM battery failure. I know this has been discussed a number of times before, but without a search function in The time-nuts Archives, I will take the easy way out, and ask you, or any one else willing to contribute.
I did just comment on that actually, so it's just weeks back.
>
> The maintenance manual I have is an Adobe PDF image that was never OCRed, so it also is not searchable.  I have not been able to find the BATTERY. 
>
> So where is it,  and are there any tricks to replacing it?

It was a fairly straightforward procedure to replace it, it sits on the
CPU board.

> Once replaced, which set of alignment steps are needed to get the instrument back to a basic time and frequency functionality?

I did the basics, see Adjustments in chapter 3 of manual. I ended not
have to do anything to the interpolator so I stopped there. It was all
very basic and not particularly costly time-wise, at least to my
recollection.

I dug out the service manual file, and it was not where I expected, but
that was good because I found a bunch of stuff gone missing. :)

Anyway, just caring to replace with correct battery and then run through
the procedures was manageable and not very heavy work. Very few parts of
this design requires tuning, and if so only slight. It's the OCXO
(10811) if one wants to have fun (and you know I do).

One of the features of this device which may be curious to know, is that
it was among the first (HP5371A it's sibling was earlier for sure) to
use linear regression for frequency estimation. This way before the
counters that would give rise to delta and omega counter naming. So,
setting it up can give improved quick frequency measures.

Cheers,
Magnus