AB Syatems 6 Channel Amp Woes

[Mark A. Gulbrandsen]

A customer has a number of Smart Devices (Actually AB Systems) 6 channel power amps in their cinemas. These amps have been a real pain and freight alone back and forth to Smart is close to 200.00 for them to be repaired plus the cost of the repair. I had a little time today as another of these amps laid a bad egg and went into protect. Turns out to be a simple failure of the power supply rail caps. This supply is one 2KVA transformer feeding what amount to three bridge rectifiers each with a 15,000 mf 100 volt cap on each of the bridges outputs for +/- supplies. Apparently all of the failuress of these amps relate back to a simple rail cap failure. Anyone else seeing this with either these or AB 6 channel amps. The Capacitirs that have been failing are Cornell Dubilier DCME1235's with a code date of 0010 on them. Other units have code date 9716 on them and these have not failed. Am I seeing a localized problem of these caps failing because of a bad batch or is something else amick in the amp thats eating these caps up.... BTW: when they fail they fail in an open state. Also apparently AB systems is barely existant any more so I doubt any help will be available from them...

Thanks!

Mark