DEC AXV11-C analog board

[Jon Elson]

On 2/8/22 16:35, Douglas Taylor via cctalk wrote:
> On 2/8/2022 5:22 PM, Jon Elson via cctalk wrote:
>> On 2/8/22 13:34, Douglas Taylor via cctalk wrote:
>>> Update on this:  I did put together a battery and 
>>> voltage divider to test the AXV11.  The label on the A/D 
>>> module says it brings the output from the multiplexer to 
>>> one of the external pins.  I was able to verify that the 
>>> voltage applied to a couple of the A/D inputs makes it 
>>> through the multiplexer when selected using the CSR.  
>>> The next output available is from the Sample and Hold, 
>>> and this is always pegged at +12v.  Am I wrong to assume 
>>> that the sample and hold will 'freeze' its output when 
>>> the A/D go bit is set?
>>
>> Well, it will probably only hold the approximate voltage 
>> for a few seconds, but should be long enough to see on a 
>> voltmeter.
>>
>> Jon
>>
> I was only using a voltmeter to look at it.
>
> I'm going to try 2 different measurements; (1) use a scope 
> to look at the S&H signal on the AXV11 and see what it 
> does over time, (2) look at the same S&H signal on the 
> Data Translation board which seems to be working.
>
The S&H will likely have a FET as the switch element, and 
those might be fairly easily damaged by external pulses.  I 
opened up some comparable Xincom modules and made minor repairs.

Jon