IcePower 400A2 + SWR SM-400

Hi there,

Going down a rabbithole trying to integrate an IcePower 400A2 class D module in an old SWR SM-400 amp. Bought the amp with a completely blown power amp so it seemed more efficient to get a module.
the transformer brings the +/-55v and +/-15v

The module asks for max +/-69v / min +/-45v and +/-12 (VDD/VSS) and Vdrive which sits +15 above the negative power rail.
All of the voltages except mains are regulated by 78xx/7912

I don’t get any sound and kind of afraid I already blew the module disturbing it’s finicky nature by my some stupid testing.

Probing on the +12 rail I get -2v drops in 0,4s intervals, the neg rail correlates. All the other voltages seem stable. The DCerror pulls low, when VD/VS is applied it starts flashing

Any leads? Not sure how to go on

Thanks a lot for your time!

I’ll attach the diy preregulator (which is followed by a 7815) and other relevant documents


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  • ICEpower1500S-Datasheet_2.1.pdf
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  • ICEpower-400A2-Datasheet-1.4_.pdf
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Hi Nisbeth, thanks for getting back!

for Vdrive I took the negative supply from the transformer referenced to ground. This i'm pre-regulating via a 27v zener and a IRF540 MOSFET which is being followed by a linear regulator 7815. The voltage in the floats around -39v referenced to ground. I also ignored the sequencing of the supply, i.e. Vdrive in the end (not totally on purpose) as for example the IcePower 1500S does.

Do you think it'd need another PSU? (Even if it'd work 55V will also only leave me with around 60% of the power)
Do you know what the Vdrive is actually doing in the module?

Warmly, J
If you are using the same transformer winding I am pretty sure you end up with issues when you try to draw power. At least for testing purposes, I would try to set it up with a separate supply for Vdrive to see if you can get it working. Other things to check would be if you are certain that you have used the right connection terminals on the module for all voltages - at least IMHO the connector pinout was not super easy to read.
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I have not looked into this particular amp, but many of the ICEpower amps need to be supplied with external +/-15VDC auxiliary supply.
That is the supply those pins are pulled up to.
How is that with your unit? If so, did you supply this aux voltage?
If not, there's nothing to pull up to and the amp will remain inoperative.