Dynahi PS + smoke = BAD

[Pars]

Quote:

Originally Posted by steinchen Unless anybody can supply a better suggestion (I won't rebuild the whole PSU on another pcb) I'm going to remove the 4700uF caps from the outputs of the opamps before I replace the OPA541. I'm going to repair the PSU next weekend and will keep you informed how it turned out.

I took a look at the original Gilmore Dynamic PSU schematic. Now I know the output devices (OPA548 vs. OPA541) aren't the same, but for the original, those fast Illinois Capacitor 5uf caps were on the output of the OPAs, nothing else. The original dynamic boards (such as Justin's V1 and V2 boards) also had no additional rail capacitance (other than a couple of 0.1uf ceramics, and the IC fast caps replaced with Wima MKS4 4.7uf typically) on the amp board; whereas the group buy boards (both Dynalo and Dynahi) have significant rail on board. Removing the 4700uf caps from the output might be a good idea... also, you might want to post this on headwize also. Perhaps Kevin or amb might comment?

 

[steinchen]

finally I got it done. First prob with repairing the psu was the package of the replacement opa541: it has short legs and can be mounted vertically only, not horizontially like the original one. So I had to cut a piece from an angle bracket to mount it to the original angle bracket. After the replacement of the opa541 output voltages still behaved weird and one LM338 was dropping only 2V so I replaced the regulators too (though I now think they were ok) ... to find out that the second opa541 was dead too ... cut a piece from an angle bracket ... btw, the ref02 is probably toast too. 50 bucks and 2 evenings down the drain.

My Dynahi is up and running again and I think it is sounding better without the large caps at the output of the psu. I'm curious how the story will continue