[time-nuts] FW: HP-5732A operation with no CRT display.

[Magnus Danielson]

Hi Lester,

I had this problem with the 5372A at work. As others have noted,
documentation of the CRT unit is for sure leaving a lot to wish for when
comparing how well the rest of the unit is documented. We could however
fairly quickly see the problem, and it turned out that a capacitor had
let out it's grey smoke. So, we replaced it and it fired up and worked.
Took care of a little trimming and it went out the lab again. The CRT
unit is fairly standard as for monochrome CRT goes, so nothing very
advanced. I usually do not service CRTs but me and my colleague did not
found it very challenging in the end. One just needs to be careful with
voltages. It was a fair bit of unscrewing to "get to it" as I recall, so
both top and bottom lid had to be popped, as well as the side lid which
hides screws.

Besides the CMOS-battery, the CRT failure is the only other service I've
had to do to the 5372As.

The "GUI" of the 5372A leaves a few things to desire, but it has it's
good points too. The GPIB command structure may be daunting at first,
but if one really reads the programming manual, your really get to learn
how everything is processed from the hardware bits, because the
preferred interface just dumps one of a number of subsets of data
register read-outs, and all the processing one needs to do it explained
in detail. It also becomes apparent that a sneak-feature is that 100 ps
resolution may be possible to support by replacing the interpolator boards.

If I had the time, I would do a modern hardware to grab data on the
fast-port connectors and dump them out over Ethernet. This would be the
way to keep the counter operating continuously with fast data gathering,
but without being limited to the 8192 samples long memory, which when
full being processed by the 68k processor before another run could be
triggered. Offboarding that the existing CPU would be used to set the
instrument up, and then all the data is gathered and processed in
somewhat more modern hardware.

Cheers,
Magnus

On 2020-06-28 16:22, Lester Veenstra via time-nuts wrote:
>  
>
> TimeNuts:   
>
>  
>
>     I have a HP 5732A with a defective CRT driver board. Since this  (A17)
> is undocumented (as no repairable) I am of course trying to work my way
> around it to see if the defect is findable.
>
>  
>
> Any A17 boards loose out there, or even better, documentation?
>
> I see good H and V sync inputs as well as the ZMod (Video data) into the
> board, bur the drive for the two deflection coils is not what I would
> expect.
>
>  
>
> Trace is some where up off crt but with vertical coils disconnected, still
> no horizontal line.
>
> With no drives connected to H & V coils, dim spot in center. Spot moves well
> in both axis with low voltage DC applied. 
>
>  
>
>  
>
> However, it occurs to me; Does  anyone have HPIB code that allows use of the
> instrument without the GUI user interface?
>
> I seem to recall some discussion of “raw data” dumps turned into useful
> measurements.
>
>  
>
>  
>
> Lester B Veenstra  K1YCM  MØYCM  W8YCM   6Y6Y
>
> lester at veenstras.com
>
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>
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