MarkBass/Class D amplifiers

[GeezerB]

Has anyone looked at or attempted repair on these types of amps? I bought one non working for parts for a song... but now I see the complexity of such a device .   It seems that they are stingy with schematics and all roads lead to approved repair shops. This one won't even power up... no power LED, no fan, no life at all.   Just learning about class D, fascinating stuff!

[g1]

You have to deal with SMPS to get anywhere with these kind of amps.
see attached

another one here:  https://docs.google.com/viewer?a=v&pid=sites&srcid=Y2Fyc3UuZWR1LnBofGpiaGFsaWJhc3xneDoyYjgyY2E5OTZmN2FjZWQ0

[Tassieviking]

What model are we talking about ?
I have only one Mark Bass service manual, the Little Mark 2.

[GeezerB]

This amp is called Combo Head II, it is in a small 12 inch combo, model CMD121P Will study the  SMPS fundamentals.  Will need it, I have established that there is 120v going in, but no power being supplied to fan, preamp, etc,. 

[mandu]

Disconnect the SMPS and power the amp with regular transformer power supply.
The problem could be elsewhere.
Regards.