[Hai-users] Omnistats not talking to Aegis any more

[Eric Rosenquist]

Problem solved!

As Scott surmised, the chip in U31 had a bad output. I have two expansion
enclosures with lots of unused outputs, so I powered everything down,
swapped the MIC2981 chip from an EE with the 2981 (an Allegro UDN2981) on
the main board and the thermostats are working now! The last output on the
EE enclosure where the UDN2981 went is now faulty, but I don't need that
output and I can always order a replacement for $3 from the HAI parts store.

Thanks to all who offered suggestions.

Eric


> -----Original Message-----
> From: Dudoussat, Scott A. [mailto:scott.dudoussat at homeauto.com]
> Sent: November 30, 2007 14:14
> To: Eric Rosenquist; HAI Users Mailing List
> Subject: RE: [Hai-users] Omnistats not talking to Aegis any more
> 
> Check Output 8 by reading the DC voltage between Output 8 and GND using
> a voltmeter.  Can you see a transition between 0 and 12 volts?  If the
> meter doesn't show a transition (i.e. steady 0V or 12V), the chip U31
> (MIC2981) that drives the outputs is suspect.  Replace U31 and confirm
> that the temperature is properly displayed.
> 
> You can purchase a replacement MIC2981 for the HAI Web Store at
> http://www.easycart.net/HAI/Hardware.html.
> 
> -Scott