Bogen Multicom 2000 relays random clicking

[Rick I]

Hi, this newbie has a one year old Bogen Multicom 2000 PA system in which the relays randomly click on as if an announcement is forthcoming but no one is touching the microphone or announce handset. Sometimes it is only one or two relays, sometimes dozens at once. We have isolated power to a clean single bus bar grounded computer circuit and also tried a backup UPS with filtering. An internal power supply to the Multicom has been replaced and software has been reloaded. Our local authorized Bogen service retailer can offer no other solutions except to ask a Bogen rep to come out which could take a while if at all. Any ideas on what could be causing this or a fix?

 

[shrtrnd]

Sorry, no.
It sounds like you've isolated all the outside variables that could cause your problem.
I'd go over the connections to all of your in/output connections just to make sure something isn't loose.
Then I'd wait for the vendor to fix their unit.
I think you did a good job in trying to isolate any outside problems.

 

[AnalogKid]

The relay board is driven by a parallel address/data bus. Bus noise or open (undriven) bus lines that react to EM noise would be seen as random commands by the relay board. If the board operates normally when given valid commands, and is plugged in securely, then the problem probably is farther upstream, as in the boards that generate the bus commands.

ak