How do I setup the trimpots?

[MarshallJMP]

The OD2 has to be set to 10.0.

Now I checked 5 MP-1's I have lying around for the moment and 4 of them have the 2k pot and one has the 5k pot.  None of them had R46 installed.

[Cpt Adama]

Ok then the S.S. section is set right with OD2 set to 10. But I am wondering why T3 has really no effect on the voltage. Should I ignore that or search for something else that could be wrong?

Another thing I noticed from the v2 PCB layout sheet, it lists R46 value as OMIT, so thats another change they made from the original schematic.

[Cpt Adama]

I've tested another MP-1 v2 which has a 2KΩ T3 Trimpot. It was initially adjusted about 1 o'clock and was 0.87KΩ. The reading from U8 pin 1 was 11.2Vp-p and adjusting T3 "SEEMED" to have no effect, just like mine. Upon further examination, if you are not looking directly at the oscilloscope while changing T3 you won't notice a change. This is a very subtle adjustment and it barely moves the wave. Until I was looking at the scope and sweeping T3 from stop to stop, I didn't notice any change.

So I went back to mine swept it back and forth and then setting it to maximize the wave and bringing it back a "hair". Took a measurement of T3 and it was 0.88KΩ and around 1 o'clock as the other MP-1.

I'm calling the S.S. setting solved.

MarshallJMP, I know you've been through a lot of these and can you confirm that the adjustment of T3 is very subtle, and hard to see unless you sweep the trim pot?

[MarshallJMP]

Yes I can confirm this.

[rnolan]

(I'm calling the S.S. setting solved.)  :thumb-up: