I was really surprised how small it is


Sounds pretty killer 

Any clips?
The proof of the pudding lies in the eating.

Get some Switchcraft jacks to easily see how they operate.

12A is a tip shorting jack, very common.

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If you want to directly see what is going on with a switched jack, just get an open style one like the panel-mount Switchcrafts.

This may be his handwriting 

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Look there's another TDA 2040

Anyhow no dice on this one either can't see jack

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But whatever message to self get a clue and a meter and start probing when the plug is plugged in

And get some compressed air and blow all those spider webs out 

I went to find a different input jack one that has some transparency 
so I could actually see the terminals making contact
What about my Crate

Nope

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Ok let's see I have a RAGE 108 but wait a minute what's this 

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I wonder if this amp has been to Canada ?!?!
 

Running to see if my Audition Chorus has it You cannot view this attachment.

Nope

Man what a trip I may have a super rare G1 modded Peavey Rage 108    

Quote from: Kaz Kylheku on September 15, 2026, 11:05:31 PMThis schematic cannot be right. It makes no sense.

Are you referring to the actual Peavey schematic (attached)?  What is wrong with it as far as the input jacks go?
You did not mention that when using the 'Lo' jack, we go through the R15 22K, but there is also R13 22K to ground (through closed tip switch of J3), so we have a voltage divider of R15 and R13.

The 3 or 6 terminal jacks are for TRS: tip ring sleeve (stereo) plugs, but can be used with standard mono TS type plugs.  With mono plugs, the ring contacts just become redundant sleeve connections.
With the 6 contact types, you have tip, ring, and sleeve contacts, plus a switched contact for each of those: tip switch, ring switch, and sleeve switch (TS,RS,SS).
When you insert the plug, you can see that the 'leaf' contacts of the jack are in contact with the plug, the switch contacts are no longer connected to any other terminals.  So the switch terminals are only closed when nothing is plugged in to the jack.


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I got home from work and straight away went out to the garage and got those input jacks

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Unfortunately they are all closed up so can't see diddly when the plug is plugged in

But it doesn't matter it's clear what's going on

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So the one above with six solder terminals I guess it has 2x sleeve (ground) connectors for whatever reason

And the PCB mount only has input and ground

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