Waldorf Microwave Rev.A problem

gregcomposition · Joined: Oct 20, 2013 Posts: 20 Location: Poland

Hi everyone!
I've got a problem with fixing the Waldorf Microwave. I bought it after a shortcut state. I repaired its power section by replacing electrolyte capacitors, positive power regulators, diodes and tantalum capacitors. I was using a service manual for Revision B (despite the differences):
Posted Image, might have been reduced in size. Click Image to view fullscreen.

Posted Image, might have been reduced in size. Click Image to view fullscreen.

.

Now the all voltages (+12,+8,+5,-5, -12V) are ok, but the synth doesn't power up properly (a display hangs on the "welcome" message and its blinking). Service mode is not accessible.
Later I saw somewhere in the net the image of power section's tantalum:

Posted Image, might have been reduced in size. Click Image to view fullscreen.

.

The second one counting from the top (connected between +8V and ground) looks like it was in reverse position (hot leg to ground). It seems to me not logical, but I've changed polarization of this tantalum and... synth turns on, works for a few seconds and then... the tantalum was fired.Does any Microwave owner would confirm position of this tantalum? Any help with a repair or service manual of revision A? I will be grateful.

gregcomposition · Joined: Oct 20, 2013 Posts: 20 Location: Poland

Solved.
If anyone is curious, the reason was a faulty power regulator +5V.
Thank you God for the brand new DOA parts...

horaciopollard2222 · Joined: Mar 19, 2026 Posts: 1 Location: norfolk

hello, i just bought a microwave 1 rev b on ebay which doesn't work Sad

i think i have the same problem you once had. heres a video of it when i switch on.

https://www.youtube.com/shorts/oDnAjg5hVo4

its gotten worse now. it doesnt load up at all. blank screen. is this a power issue? easy repair? any advice would be most gratefully received.