Hi guys, anyone here familiar with these amps?
The one I have has no output from the PSU board, when switched on it draws a very small amount of power from the mains (I can see my current limiter bulbs glow very very dimly) but that is all.
I have the schematics but for the life of me can't figure out how this amp is supposed to power up
I have about 250V DC on VRECT and CTRSWITCH (when the front power switch is on) but I have no VAUX so I can't see how it could ever power up in this condition.
As much as I have looked over the schematics I can not understand where VAUX is derived. I would have expected to find a small switch mode or even a regular mains transformer providing VAUX, but no. All I can see is VAUX comes from A on SCH.QD-ALSU but it isn't obvious to me how that should work.
Or maybe I am totally misunderstanding how this amp should start up?
Also, to improve my own knowledge, while examining the schematics I did notice that Q3/Q4 form part of a PFC circuit to give VBOOST but what is the purpose of M1 in the same circuit?
Schematic attached. The version PSU I have is the SCH.QD-ALIN-14EN.01 version
The one I have has no output from the PSU board, when switched on it draws a very small amount of power from the mains (I can see my current limiter bulbs glow very very dimly) but that is all.
I have the schematics but for the life of me can't figure out how this amp is supposed to power up
I have about 250V DC on VRECT and CTRSWITCH (when the front power switch is on) but I have no VAUX so I can't see how it could ever power up in this condition.
As much as I have looked over the schematics I can not understand where VAUX is derived. I would have expected to find a small switch mode or even a regular mains transformer providing VAUX, but no. All I can see is VAUX comes from A on SCH.QD-ALSU but it isn't obvious to me how that should work.
Or maybe I am totally misunderstanding how this amp should start up?
Also, to improve my own knowledge, while examining the schematics I did notice that Q3/Q4 form part of a PFC circuit to give VBOOST but what is the purpose of M1 in the same circuit?
Schematic attached. The version PSU I have is the SCH.QD-ALIN-14EN.01 version
Comment