Nutcase Kook wrote:



This is a Mark Bass amp with low speed start and on-demand speeding up
circuit. I replaced it with 12V 2A and that was sufficient to
(presumably) overload the 18V, or so, line off the SMPS and amp goes
into protect. Not even a slight kick of the impellor
Tried the original again, and that is fine.
Tried a 12V ,.15A one and again protect mode, same sort of start up
current draw as the original, but goes into protect.


** The above drivel makes no sense whatever.

The switching PSU in the Mark Bass "Parsec" series is unregulated and has no remote shutdown system. The DC supply for the fan is also unregulated and not sensed.

"Protect" mode, when triggered, mutes ( labelled DIS on the schem) the input signal the power amp and detects overtemp or excess current in the output MOSFETS.

The speaker relay operates independently and senses only large DC offsets.

http://bmamps.com/Schematics/Mark_Ba...le_Mark_II.pdf



..... Phil