DEC AXV11-C analog board

[Jerry Weiss]

These A/D systems use methods to isolate the sensitive analog signals 
from the electrical noise and ground plane of the computer.  Typically a 
differential input is standard, so you will probably need wire up two 
inputs.

If this is your first time with A/D, suggest you toggle in some code to 
trigger and report the A/D conversion repeatedly and use a small voltage 
battery with a potentiometer divider to drive the inputs.      Most of 
the analog inputs should be high impedance and while not impervious, can 
take +- 30v w/o damage.

  Jerry




On 2/6/22 11:43 AM, Douglas Taylor via cctalk wrote:
> Yes, I am putting 1 into the CSR to start the conversion and I do get 
> a 200(8) indicating that the conversion is complete.  I wonder if this 
> means the A/D chip is OK but something else, like the multiplexer chip 
> or gain amp is fried.
>
> On 2/6/2022 12:33 PM, Jerry Weiss via cctalk wrote:
>> Are you triggering an A/D conversion via the CSR or external signal?  
>> Then check the A/D done bit.
>>
>> See  EK-AXV11-UG-02 Chapter 4.
>>
>>    Jerry
>>
>> On 2/6/22 11:20 AM, Douglas Taylor via cctalk wrote:
>>> I have one of these and would like to use it, however it appears to 
>>> only partially work.  Here is what I have found that works and what 
>>> doesn't:
>>>
>>> 1. CSR and DBR are present and operational.
>>>
>>> 2. Jumpers set to 'factory'.
>>>
>>> 3. D/A portion works, can deposit codes in ODT and see voltages out 
>>> on DAC pins that change depending on the octal value deposited in 
>>> CSR+4 or +6.
>>>
>>> 4. A/D portion returns full scale code, either 3777 (2's compliment) 
>>> or 7777 (offset binary) whether in the input is open or shorted to gnd.
>>>
>>> I think the problem is that the A/D inputs are not exactly protected 
>>> and damage has occurred to this portion in the past.
>>>
>>> Does anyone have any info on the A/D module?  Who made it? Can you 
>>> open it up?  Does XXDP have a test for this?
>>>
>>> Doug
>>>
>