What mod is this?

[cerealk]

Dear All,

ADA MP-1 owner since 1993 here and about 2012 I had a small mod done to my ADA based on schematics I found on the old ADA depot website. I have looked high and low and cannot find the mod anywhere or what it was!

Here are two pics of what was done. Please can someone tell me what this Mod was and also, hopefully, have one of the old pdfs of it!

A huge thank you in advance!

Best wishes

Simon
A Brit in Australia

[cerealk]

Thanks to MJMP!

This was the NMI mod, which was a 1992 recommended ADA update to older models.

[scole]

Nice! Always great to get an answer to a mystery! Gives me the idea for a new post as I discovered something while troubleshooting my no output issue.

[MarshallJMP]

This update is can also done on older V1 models from the factory, but the resistor will be mounted on top between 2 IC's.