Aleph 5 Help

Need some help.

just finished my aleph 5 with Kristijan Boards.


very low sound, heavy distortion.

no hum.

The irfp240 fets don't heat up - what is supposed to be their terminal voltage?

only the irfp9610 get a bit warm

I've got 34V on each rail, IRFP240 and ZTX450 instead of MPSA18.

didn't mount the led.

all other components are like the schematic.

Is there any test to find out the fault?

Should I try out the other channel?



2002-09-12 11:14 am

I am also building an aleph with Kristijans A5 boards -they are really nice!

Only I am doing it as an A30 because of my powersupply
(+/- 25V).

I've had lots of problems, but they where caused by me.

Waiting for new parts now

Try to measure all the voltages from the A5 service manual, and tell us what you get. There is a fault in the manual; there should be something like 0,66V across the source resistors.

Maybe then we get a starting point for fault finding

-careful with those probes

here are some other pics of my incomplete aleph 5

the first one is a side view.

there you can see the PCB the caps, trafo, bridge and on/off relay.


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Beautiful amp. The reason the bottom sink is staying cooler is because it is the farthest awy from the heat source. The heat can only get there by traveling throuh the the connecting bars and where the sinks touch. Try putting some bars vertical along the heat sink seams. Aluminum if you have it. Good luck, Mike.