Re: DAC failure mode

On Feb 28, 6:35 am, Robert Latest <boblat...@xxxxxxxxx> wrote:
Hi folks,

currently I'm looking at a piece of equipment (a PC32 DSP board from
Innovative Integrations) that has an AD669 D/A converter on board.
Instead of the desired sweep from -10V to +10V, I get an odd
assortment of linear pieces that looks like this:

output
^
+10 | / /
| / /
| / /
+5 |/ /
|
|
|
0---------------------> command (0-FFFF)
/ /
/ /
/ /
-5 / /

It looks like the dac's 2nd to the MSB bit is stuck high
all the time, perhaps a problem on the PCB? At any rate,
that's an issue on the input side of the dac, not on the
output side, so "touching" the card couldn't be a cause.

.