HELP with broken Pignose Amp

Deadman1

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Hello!

I got a "good-ish" deal on a Pignose Legendary 7-100 Amp.
They are kind of rare over here... and it was from my birth year. So I thought I'd get it... without knowing if it works (neither did the seller)... - and it doesn't.

First thing that's really broken is the knob / potentiometer.
It fell apart when I turned it.

I have some questions regarding the potentiometer and the power draining.
The original potentiometer worked like a switch... so when turned off... it made a clicking noise and some pushback.

QUESTION 1: What are these pots called?

QUESTION 2: Anyone knows the pot value... the thing is broken so I cannot measure it. And there are no markings.

QUESTION 3: I have no idea how the circuit or the pot works. Can I use a regular audio taper pot and it will also be "off" and drains no battery, when turned to 0? Is the pushback just a haptic feature?

If it will still drain... I thought about installing a regular audio taper and an extra DPDT switch, which I solder between the battery hot wire..
Does that make sense,

Thanks in advance for any Help!

Kind regards :)

d.
 

NoTeleBob

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You can buy pots with an on/off switch on the rear. As you get to "0", it engages the switch and shuts the power off.

They used to be common but you might have to hunt around a bit to find one. I don't know the suppliers over there. As an alternative, you could use a push-pull (easily available now) to switch the power. You'd have to check the power rating though... the old school ones likely handled more power.

I'd start by hunting for a schematic via google. If there's a revision number or year, etc, that might help identify the correct schematic in your search. It sometimes takes a couple hours of hunting and pecking to find a schematic for something older.
 
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W.L.Weller

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Alpha p/n: RV24A02F-10-15S1-B50K

Not sure who the Mouser/DigiKey of the Eurozone is, but 50K linear taper pots with integral switches are not impossible to find (the "click" on and off is not just haptics, there's mechanical switching between electrical contacts causing the "click")
 

Lowerleftcoast

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...and listed in the *Forums* there is the *amp owners club* where a Pignose group gathers. I have the big pigs... G40V and G60VR but there are many more of the 7-100 owners there. So, if you don't find your answers in the *Amp Tech Ctr* thread you might try there.
 

fraser

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Heres a page with the schematic etc...

he shows the pot as a 50 k linear.

the one you want is often called an on/off switching potentiometer, but there are various variations with the same meaning.

looks like the battery is engaged when the plug is inserted into the jack, and my pignose doesnt turn on without a plug inserted, so maybe you can get away with a regular pot and just unplugging when not using it.

but i dont think itll be hard for you to find a switching pot, they are fairly common
 

Deadman1

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You can buy pots with an on/off switch on the rear. As you get to "0", it engages the switch and shuts the power off. I don't know the suppliers over there.

They used to be common but you might have to hunt around a bit to find one. As an alternative, you could use a push-pull (easily available now) to switch the power. You'd have to check the power rating though... the old school ones likely handled more power.

I'd start by hunting for a schematic via google. If there's a revision number or year, etc, that might help identify the correct schematic in your search. It sometimes takes a couple hours of hunting and pecking to find a schematic for something older.

Thank you! the push-pull idea isn't bad.

Looks like a 50k linear switch pot.

url
Wow thanks so much!

url

Alpha p/n: RV24A02F-10-15S1-B50K

Not sure who the Mouser/DigiKey of the Eurozone is, but 50K linear taper pots with integral switches are not impossible to find (the "click" on and off is not just haptics, there's mechanical switching between electrical contacts causing the "click")
Sweet now i have some keywords to find this thing :)

...and listed in the *Forums* there is the *amp owners club* where a Pignose group gathers. I have the big pigs... G40V and G60VR but there are many more of the 7-100 owners there. So, if you don't find your answers in the *Amp Tech Ctr* thread you might try there.
Good idea - thank you!

Heres a page with the schematic etc...
url

he shows the pot as a 50 k linear.

the one you want is often called an on/off switching potentiometer, but there are various variations with the same meaning.

looks like the battery is engaged when the plug is inserted into the jack, and my pignose doesnt turn on without a plug inserted, so maybe you can get away with a regular pot and just unplugging when not using it.

but i dont think itll be hard for you to find a switching pot, they are fairly common

Thanks so much..
about the battery and the plug...
@fraser @Lowerleftcoast @W.L.Weller @NoTeleBob
is there any way i can measure this with the multimeter wether it is draining the battery, when nothing is plugged in or not?
because if this is the case... i absolutely wouldnt mind using a "normal" pot...
 

Lowerleftcoast

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If the pot is the only problem with this 7-100, it looks like the vol pot and switch can be by-passed while you wait for a replacement. The guitar volume can serve as the vol control.

As mentioned above when the guitar is not plugged in it should disable the power.

You can meter for 9VDC at R6 and/or R10 to see if power is *on*.
 

Gunny

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Thank you! the push-pull idea isn't bad.


Wow thanks so much!


Sweet now i have some keywords to find this thing :)


Good idea - thank you!



Thanks so much..
about the battery and the plug...
@fraser @Lowerleftcoast @W.L.Weller @NoTeleBob
is there any way i can measure this with the multimeter wether it is draining the battery, when nothing is plugged in or not?
because if this is the case... i absolutely wouldnt mind using a "normal" pot...
Lift the end of one of the batteries and connect your multimeter (current measuring mode) between the battery terminal and it's normal connection point. That will show if there's current being supplied from the battery when nothing is plugged in.
 

Deadman1

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If the pot is the only problem with this 7-100, it looks like the vol pot and switch can be by-passed while you wait for a replacement. The guitar volume can serve as the vol control.

As mentioned above when the guitar is not plugged in it should disable the power.

You can meter for 9VDC at R6 and/or R10 to see if power is *on*.
Thanks for the Info!!

If you don't want to use a switch pot, you could always add a hole and install a switch *and* a pot.
haha... thanks yeah... might do that in the end... wanted to mod this thing a bit anyway so another few DPDT switches won't bother anyone ;)

Lift the end of one of the batteries and connect your multimeter (current measuring mode) between the battery terminal and it's normal connection point. That will show if there's current being supplied from the battery when nothing is plugged in.
Oh this is a great info! thanks
 

Deadman1

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Thank you very much for all the help @fraser @Lowerleftcoast @W.L.Weller @NoTeleBob @SherwoodGreen @Gunny !
I kinda f*cked it up...

I used a regular potentiometer. 50k Audio Taper (i thought it would be better controlable than linear?)
But when finished, it wasnt working correctly.
aside from the hum.... when dialed on around 8-9 it was barely as loud as my laptop speaker...
when dialed on 10.. the sound was gone..
Could this happen due to a bad soldering job? (It was little space to work in there and i had troubles working... so this could be possible)

so i took it apart again...
when i tried taking everything apart...another 2 wires 'fell' off
and i am not sure if i rewired everything correctly, as i wasnt able to see where the wires come from and what the colors mean.

the next days i will take it apart completely and try again
 

W.L.Weller

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The other forum thread linked above does include this rundown of the offboard wiring:



And looking at the position of that volume pot, it is basically replicating the volume control on your guitar. If you wanted to, I think you could do away with it altogether and just have an on/off DPST switch, controlling the overall volume with your guitar.

Are you powering it with batteries or a 9V adapter?
 

Gunny

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when dialed on around 8-9 it was barely as loud as my laptop speaker...
when dialed on 10.. the sound was gone..
That makes no sense, so yes - there's a wiring error with your pot or else the pot is defective. In theory, the audio taper should work better than a linear pot. Sounds like you have it wired in reverse. With the pot out of the amp, measuring from the wiper to one of the end connections, check resistance at 50% rotation. Is it ~25K? if so, you've got a linear pot.
Second test: rotate the pot fully clock wise and see which leg has 0 or almost 0 Ohms with respect to the wiper. That (end) leg must connect to the 'hot' input connection on the jack that you plug your guitar into. So, identify the spot on the circuit board (where the pot connects) to verify which of the 3 connections has continuity to the input jack hot lead connection. Then ensure your pot leg from the second test is soldered to that point.
 




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