MIAC Transistor OutPut Damage

[james87price]

Dear all,

I have been using a MIAC as a PLC to control some E/P valves. This involves using the PWM outputs to provide a controllable voltage signal, and all has been working mostly very smoothly. My question is two part and I have a nasty feeling may be linked:

1.
I am using 2 MIACs to use 4 PWM outputs. The filter I have is a 2 channel filter so I have signal A from both MIACs linked and going to channel 1 and similarly signal B going to channel 2. This is designed to allow the operator to set-up multiple or more complex tests. The weird effect is that when the signal is set-up on the 1st MIAC the LED turns on on the 2nd MIAC, feeding current the wrong way into the output. It has been working ok for now, and has been sufficient while I wait for my 4 channel filter. Could this reverse current damage the transistors? Can I get away with the 2 channel filter?

2.
The output I am getting from 1 of my MIACs is not what the code is asking from it and not the same as the other MIAC. I have logged it and it is effectively zero with a few random spikes. Is this a coding or hardware fault and could the reverse current, as explained above, have done it...? What are the options for return, repair etc?


Thanks yet again for your replies and help.

James

[LeighM]

Hi James

Yes, it does look as though there is most likely damage to at least one of the MIACs. The motor outputs should not be directly connected together as they can sink and source current.

For returning the faulty unit please see http://www.matrixmultimedia.com/returns_policy.php

If you would like to post your filter circuit then we could perhaps advise on adjustments to it, although you mention you have a 4 input filter to use soon, which hopefully will resolve your application issues.

Regards,
Leigh