2 replies to this topic

[basschase]

I have a MA600 and a MA1200, that are both well worn, but are old friends. Both of these amps tend to kick on and off a few times when powering up, making a considerable thump that sounds deadly to my drivers. I'm curious if it's an issue in the ODEP circuitry, or a deeper problem..forgive me if it's an issue covered before, but I'm a "newbee" here..

[basschase]

It would appear, if any signal passes through to the amp during the intial startup, it causes the togggling back and forth, and lights to go on and off, making that horrid sound..as if some signal confuses the ODEP circuit in the inital startup process...possibly the amp has some self-diagnostic process that it going "catty-wampus" at power-up??..

[KGring]

It is possible that there is a leaky capacitor on the low voltage supply (C1 or C2 on the main board). If this is happening, the negative or positive side of the display may be powering up faster than the opposite side. This is compounded if there is a signal load on the amplifier.

It would appear, if any signal passes through to the amp during the intial startup, it causes the togggling back and forth, and lights to go on and off, making that horrid sound..as if some signal confuses the ODEP circuit in the inital startup process...possibly the amp has some self-diagnostic process that it going "catty-wampus" at power-up??..