MA sequencer not sequencing

[Brentgi]

I have a Middle Atlantic USC-6 that is no longer sequencing. The indicators on the front panel are sequencing, but it is not switching any of the modules (RLM-20's). They are set to auto but will not power-on when sequenced. For now, we've got to keep each module in the always on state.

Any ideas?

 

[microstar]

Call Middle Atlantic support?

 

[Amiers]

Did you crack it open and see if the fuses are still good?

 

[microstar]

From the USC-6 manual:
"Power Supply Fuses: In addition to the master switch/circuit breaker, the DC power supplies are protected by two fuses. One located internally, which DC protects
internal components, and one located on the rear panel (1.5A MAX) which protects output circuitry. An overload on the external customer provided wiring will have no effect on the internal voltage power supply or its associated fuse." Although this is probably not the problem since it also states not to use the 12vdc outputs for the RLM modules, only the dry contacts.

 

[MNicolai]

Do you have a key or button activation somewhere that may be stuck or the wiring may be shorted on?

Are the wires for each step landed on the 12VDC terminals or on the dry contact terminals?

If you disconnect all the cabling on the back of the unit and hook a DMM up in continuity mode between the relay contacts (not the 12VDC+/-) of a given step, does the continuity meter register any change in state when the unit sequences up/down?

If you strip the power supply fuse out, does a DMM read continuity or a low resistance across the fuse or is the fuse blown?

Beyond that, you might have to send the unit in for repair if you have verified it's not cycling steps. Middle Alantic's usually pretty good to work with but should you need to replace it, the MPR-SEQ-1CA does basically the same thing for less than half the price, just not in a 1U rackmount chassis. There's also a bunch of the rackmount versions on eBay for cheap -- since most installation power amplifiers these days are digitally controlled or have dedicated contacts built in for power on/off a lot of these USC-6R's are getting pulled out of renovated systems and demand for them is going down.