Rich Mod PPIMV - Help

[bds9487]

I'm trying install the rich mod PPIMV on my Marshall 1959spl reissue, the newer one with the fx loop. Can any of you tell me if I've identified the correct place on the circuit board to insert the mod? See the picture below. Thanks for your help.

Here's a large view of the circuit board:

http://sidener.com/photos/marshallAmps/marshall1959CircuitBoardppi.jpg

and, here's the schematic:

http://www.drtube.com/schematics/marshall/1959-01-60-02.pdf

 

[Vrad]

Yes that's the right spot. Thats' the Phase Inverter.

 

[bds9487]

Yes that's the right spot. Thats' the Phase Inverter.

Thank's Vrad. You da man!!!

 

[Vrad]

Yes that's the right spot. Thats' the Phase Inverter.

Thank's Vrad. You da man!!!

Anytime...
One thing I did... not sure if you want to try this or not... I used 470K resistors in place of the 220K. When I did the math originally, the pot turned all the way up did not equal the 220k resistance and the amp always sounded very mushy and brown. With higher resistor values, the pot at 10 the resistance is close to the original 220k. If that makes any sense...

 

[bds9487]

Yes that's the right spot. Thats' the Phase Inverter.

Thank's Vrad. You da man!!!

Anytime...
One thing I did... not sure if you want to try this or not... I used 470K resistors in place of the 220K. When I did the math originally, the pot turned all the way up did not equal the 220k resistance and the amp always sounded very mushy and brown. With higher resistor values, the pot at 10 the resistance is close to the original 220k. If that makes any sense...

Thanks for the tip. That sounds like a great idea. Hopefully, I'll have time to try it tonight. I'll let you know how it works.

 

[Vrad]

Yes that's the right spot. Thats' the Phase Inverter.

Thank's Vrad. You da man!!!

Anytime...
One thing I did... not sure if you want to try this or not... I used 470K resistors in place of the 220K. When I did the math originally, the pot turned all the way up did not equal the 220k resistance and the amp always sounded very mushy and brown. With higher resistor values, the pot at 10 the resistance is close to the original 220k. If that makes any sense...

Thanks for the tip. That sounds like a great idea. Hopefully, I'll have time to try it tonight. I'll let you know how it works.

Sure thing... And so it begins...

"Do I like a 220k/330k/470k reisistor?"
"Do I like a 250k/500k/1meg pot?"

 

[jerrydyer]

right spot but the yellow drawing scares me. Depending on which one you are using, the one that keeps the 220k's or the one that gets rid of them as to there are two 2.2meg resistors on your dual 250k pot. you break the connection between the orange and green wires to the 220k res on the power tube side.

 

[bds9487]

right spot but the yellow drawing scares me. Depending on which one you are using, the one that keeps the 220k's or the one that gets rid of them as to there are two 2.2meg resistors on your dual 250k pot. you break the connection between the orange and green wires to the 220k res on the power tube side.

Sorry Jerry, I'm not following you. I'm assuming the the caps and resistors are soldered together where the yellow lines are. If my assumption is correct, that's where I plan on breaking both connections and inserting the pot. Would that be correct?

 

[Vrad]

right spot but the yellow drawing scares me. Depending on which one you are using, the one that keeps the 220k's or the one that gets rid of them as to there are two 2.2meg resistors on your dual 250k pot. you break the connection between the orange and green wires to the 220k res on the power tube side.

Sorry Jerry, I'm not following you. I'm assuming the the caps and resistors are soldered together where the yellow lines are. Is that not correct?

If I remember correctly, the Rich Mod uses a dual pot. I think the caps get one pot and the resistors get the other pot.

 

[bds9487]

right spot but the yellow drawing scares me. Depending on which one you are using, the one that keeps the 220k's or the one that gets rid of them as to there are two 2.2meg resistors on your dual 250k pot. you break the connection between the orange and green wires to the 220k res on the power tube side.

Sorry Jerry, I'm not following you. I'm assuming the the caps and resistors are soldered together where the yellow lines are. Is that not correct?

If I remember correctly, the Rich Mod uses a dual pot. I think the caps get one pot and the resistors get the other pot.

I believe it is a dual pot, Vrad.

 

[Vrad]

right spot but the yellow drawing scares me. Depending on which one you are using, the one that keeps the 220k's or the one that gets rid of them as to there are two 2.2meg resistors on your dual 250k pot. you break the connection between the orange and green wires to the 220k res on the power tube side.

Sorry Jerry, I'm not following you. I'm assuming the the caps and resistors are soldered together where the yellow lines are. Is that not correct?

If I remember correctly, the Rich Mod uses a dual pot. I think the caps get one pot and the resistors get the other pot.

I believe it is a dual pot, Vrad.

Yup... so it's connected like that pic...

Just put another 220k or so in series with the other 220k's and you should be good to go.

 

[bds9487]

Here's the document I've been working from:

http://sidener.com/docs/marshallAmps/PP ... 20Step.pdf

 

[Vrad]

Here's the document I've been working from:

http://sidener.com/docs/marshallAmps/PP ... 20Step.pdf

Yep.. Same as the pic I posted.
Dual 500.

 

[jerrydyer]

take a good look at this. if you do this one as it its prob the best otherwise use a dual 500k audio pot and leave the 220k's

 

[bds9487]

take a good look at this. if you do this one as it its prob the best otherwise use a dual 500k audio pot and leave the 220k's

That's quite different than the diagram I've been working from. Is this considered the Rich Mod, Jerry?

 

[jerrydyer]

they both work great the one with the 2.2 meg res has a safety feature..

 

[Vrad]

And just to make things even more interesting... there's also the Lar-Mar PPIMV. Haven't tried that one, but folks seem to love it.

 

[Greazygeo]

And just to make things even more interesting... there's also the Lar-Mar PPIMV. Haven't tried that one, but folks seem to love it.

They all stink. You can only go down about 1/4th before the tone starts getting messed up.

Yes Im bored.

 

[Vrad]

And just to make things even more interesting... there's also the Lar-Mar PPIMV. Haven't tried that one, but folks seem to love it.

They all stink. You can only go down about 1/4th before the tone starts getting messed up.

Yes Im bored.

No... you're absolutely right...
I had to pair my Rich Mod with a Hotplate.

 

[Greazygeo]

And just to make things even more interesting... there's also the Lar-Mar PPIMV. Haven't tried that one, but folks seem to love it.

They all stink. You can only go down about 1/4th before the tone starts getting messed up.

Yes Im bored.

No... you're absolutely right...
I had to pair my Rich Mod with a Hotplate.

I just had a guy bring me a metro amp he was trying to put in one of these masters. Told me it worked for a few minutes then quit. I don't see how it could have ever worked, he didnt have it wired right, not a big deal easy to get this stuff mixed up. He did a great job on the layout, soldering and such. Just think he looked at it too hard probably.

Anyway, playing it reminded me how much I hate these masters!