New to me Marshall 1974x, can you identify this mod as a PPIMV?

[giogolf]

Hey all,

Up until 2 weeks ago, I never knew this amp existed. TBH, I wasn't really a Marshall type of player even though a majority of the music I listen to is 60/70s Blues Rock. I am very familiar with the JTM 45, Bluesbreaker Combo and then the Plexis to follow, up to the JMPs and their combo variants. But I didn't know Marshall actually made an 18w Plexi'ish small combo in the 60's. In a local craigslist search I came across a listing for a 1974x for an excellent price considering new these things are way overpriced. Picked up, opened up to give it a health check and noticed someone was in there and done some mods.

1st, someone installed a London Power Scaler SV2, but didn't install the VCK and tone shaper. I have removed all that, because the work was soppy at best. In addition to that someone installed a remote lead to what I think maybe a PPIMV. I am including a picture, and placed a Red Star where all the connections are.

If someone can identify what it actually is and explain to me how it's supposed to work, I'd greatly appreciate it.

PPIMV.JPG

PPIMV2.JPG

[JMPGuitars]

It's hard to see what's going on there exactly, but I'll give you a guess, and you can try and confirm.

I'm guessing there are 3 wires there, with 2 connecting to the grid reference resistors. The 3rd wire I would assume is a shield. My assumption is the other end of that wire would be connected to a potentiometer that would effectively make it what I call the "stupid simple master volume."

See if it makes sense compared to this:

Stupid Simple Master Volume.jpg

Again, I'm making a guess here, you'll need to confirm. There's some ugly things going on in that amp. Hopefully it sounds good.

Thanks,
Josh

[giogolf]

It's hard to see what's going on there exactly, but I'll give you a guess, and you can try and confirm.

I'm guessing there are 3 wires there, with 2 connecting to the grid reference resistors. The 3rd wire I would assume is a shield. My assumption is the other end of that wire would be connected to a potentiometer that would effectively make it what I call the "stupid simple master volume."

See if it makes sense compared to this:
Stupid Simple Master Volume.jpg

Again, I'm making a guess here, you'll need to confirm. There's some ugly things going on in that amp. Hopefully it sounds good.

Thanks,
Josh

Yep that's exactly what it is, based on your diagram... The amp sounds great to me. Can you elaborate on what the ugly things are so I can correct them?

[JMPGuitars]

Yep that's exactly what it is, based on your diagram... The amp sounds great to me. Can you elaborate on what the ugly things are so I can correct them?

If you don't have any audible issues you can ignore it and enjoy the amp. If you're bored and want to mess with it, read the modern ground schemes thread in my signature.

Thanks,
Josh

[giogolf]

Yep that's exactly what it is, based on your diagram... The amp sounds great to me. Can you elaborate on what the ugly things are so I can correct them?

If you don't have any audible issues you can ignore it and enjoy the amp. If you're bored and want to mess with it, read the modern ground schemes thread in my signature.

Thanks,
Josh

Thank you, will do!