MP-1: Is this a mod

[kfowler8]

I took off my covers tonight to change out the battery and start prepping for the rear jack mod. I noticed this black jumper wire that looked out of place. Is this some kind of mod? If so, what? The only mods I know that have been done on this unit is the battery mod and the update to version 2.

Thanks,

[MarshallJMP]

This is normal,no mod.

[kfowler8]

Thanks!!!!!!

[El Chiguete]

I guess someone notice they forgot to do that in the board design and had to do that to ALL of them latter! jejeje.

[MarshallJMP]

This was fixed in the V2 mp-1's.This is a sort of factory mod to fix some ground problems.

[kfowler8]

Got it all working now. Took longer to de-solder everything than it did to run the new lines. Works great.

[rnolan]

Good to hear  :thumb-up: :whoohoo!:

[WickedBlade]

Hey guys,

I just noticed that I don't have that wire on my v1 MP-1.
MJMP, would you advise to do this little wiring? I don't think I have ground issues, so maybe "if it ain't broke, don't fix it" should apply?
BTW my board is 423 rev E, whereas kfowler8's is ref F so maybe the issue was introduced with rev F...

[MarshallJMP]

Like i said not all mp-1's have this,can you take a pic of the board so i can check?

[WickedBlade]

Here's a picture of my actual board.

I should mention that it was taken years ago, before I applied any mod, but I don't think that affected the board (I applied the noise mod, MDRT, new filter caps).
I may have applied some fixes from the april 1992 'troubleshooting' mail too, but not the MIDI board Ke/Kd wire thing (that I remember of, anyway). I suspect that is the subject at heart, here...

[MarshallJMP]

That's an old board,what is the REV letter of the mainboard.Can you also take a pic of the mainboard?

[WickedBlade]

Wow, you're fast! BTW I just edited my message above.

Mmmm the main board is a Rev B (B is handwritten). See the attached picture. As before, this was taken before any mod was done (so you can see the original tranny which I changed from the MDRT).

[RobbHell]

Not that its a must be the red wire on the  (KB connector)  was clipped. I noticed your T2 trimpot was set rather low. Are you a little gain user?

[MarshallJMP]

Well this is an old board and it will work without the wire like it is.You can do the update but only if you have ground problem,else i would leave it like it is.

I attached the PDF update file,the update is #8 and #9.

Do you still have the ZETA chips in there?If so i would replace these with the VACTEC's see #6

[WickedBlade]

Sorry guys, I was away for a few days.

Not that its a must be the red wire on the  (KB connector)  was clipped. I noticed your T2 trimpot was set rather low. Are you a little gain user?

As I said, the pictures were taken years ago, as I was unpacking my latest acquisition. I have no clue how my T2 trimpot is set today, but I am entirely satisfied with my gain. I'm using a Pornograffitti-style tone, so there's enough gain for me, and plenty more on tap.

Well this is an old board and it will work without the wire like it is.You can do the update but only if you have ground problem,else i would leave it like it is.

I attached the PDF update file,the update is #8 and #9.

Do you still have the ZETA chips in there?If so i would replace these with the VACTEC's see #6

Thank you for the advice, I'll leave the unit as it is now, since I have no ground issue.
I had done the mods described on your paper already (while I was doing the noise-mod) and I do have Vactrols in place now. That picture is seriously out-of-date :)

Thanks again.