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Dead MP4 need help

2012-10-23 by iscrites

Hi all,

I'm a owner of a japanese old revision MP4 that died on me yesterday.

What happened:
- I just finished modding the MP4 with several great mods I found here (the MG1 speed and EG speed). It was working fine than I decided while I was on it to check on the FX on switch that was not working correctly.
So I had to remove the KLM354 board first (I never did it so far) to reach the switch. I resolder the switch and then I powered the synth on, while still having the 354 board not in place (but fully plugged). I check that there was no shorting whith the 354 board floating. It seems ok.

But when it powers on I did not see the leds go on and a few seconds later I saw smoke coming from the 354 board. I immediately turned it off. I checked where it could come, it seemed coming from the SSM2033 but I could not confirm, I could not find a part that was really hot.
I put the 354 back in place, checking every connector to see if there was some loose or some shorts.
When I second turn the synth on the MG2 led showed, followed by MG1, though they seemed dimmed. I could play the synth for a second and then it completely died and I could not turn it on since that.

Now I don't know the exact damages and would like some help to revive it.

What is sure is that the 376 board is damaged because I don't have the +15v -15V or 5V.
So far the reading I got are (schematic is here: http://fa.utfs.org/diy/korg_monopoly/mp_10_klm-376_powersupply_klm-357_vcoheater_schemo.gif):
- 26.5v out of the transformer (on KLM376/ cn37 connector)
- +37v and -37v from the 1S1885 diodes to the inputs of the M5230L (pin 7 and 4)

I have no output reading from the M5230L. So does it means this one is fried or can it be some other componant that makes that I have no output from the M5230L ?
I'm not a real technician, I don't know much but if someone can explain I can track the problem.

Hope someone can help.
Thanx in advance

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