crate gfx-212 - bad input?

[bustamooooove]

I have been working on a crate gfx 212 that was given to me by someone who didn't care to fix the input jack. I figured that was easy enough, but evidently, it wasn't all the problem.

Now, I plug into the 'insert' jack, and I get plenty of volume but lose all my tone controls. That has always worked.
I plug into the new 'input' jack, and I can use all the controls on the amp, but it plays at an almost inaudible volume.

The only thing i have been able to do to increase volume while using the 'input' jack, was to put just the tip of a cable into the footswitch jacks in the back of the amp. If i put the cable in the whole way, it makes no difference, but if I just put the tip in and make contact it seems to boost volume, but still nowhere near as loud as this amp should be.

First possibility - I replaced stock mono jack with a stereo jack, but i figured if i left the middle ring empty it would serve the same purpose. Could this be the problem?

FYI -

-I have resoldered all the joints on the bottom of the board, and replaced what I thought was a bad bridge rectifier, to no avail.
-I have made noise through the input while moving all of the dials from 10 to zero and back to 10, to make sure it wasn't a faulty pot.
-I have tried plugging things into the effects jacks, but this has no effect (sorry for the pun).

I am all out of ideas and would really hate to scrap this amp after putting this much effort into it.
Any ideas would be greatly appreciated.
I tried to link a manual here, but couldn't find it.
Thanks in advance!

[Jazz P Bass]

TRS footswitch jack

The footswitch jack is stereo. Tip, Ring, Sleeve.
Tip is gain boost, Ring is channel select. Sleeve is ground (zero volts)
That is what is happening at the FS jack.
Insert is part of the FX loop, is it not?
In that case, you have bypassed the preamp controls.
What happened at the input jack, I do not know.
Why was it replaced?
You may have ripped up or cracked traces on the circuit board.

[bustamooooove]

The input was replaced because it got hit while a cable was in it and bent it. That's the only history i know. I've replaced them before though, so I knew it wasn't bad.

The circuit board seems ok to me, i haven't bent it or dropped it or anything but I'm not very experienced with it.. Any telltale signs to look for ripped/cracked traces?

[Jazz P Bass]

Crate GFX

Here is the schematic.
With the amplifier off, insert an instrument cord into the input jack.
At the other end of the cord measure the sleeve resistance to ground.
Should be zero ohms.
Now measure the tip of the cord and see if you have continuity to C 3.
Also, I do not know what C9 is doing there, but if it is leaky you may have 40 Vdc on the tip.
With the amplifier on, measure the Vdc from tip to ring of your input cord. Should be 0Vdc.

[Enzo]

C9 is connected to ground, so if it shorts, it will ground off the 40v supply. It won;t get on the tip.

You plugged into the insert jack and the power amp worked through the speakers. That is only half the test. Plug the guitar into the regular input, and a spare cord into the insert. And the opther end of that cord into the input of some other amp. SO we can listen to what is there. You have to pull the plug half way out of the INSERT jack.

And I am concerned about the insert jack itself. With some signal playing into the amp, look down at the insert jack contacts. Push down on each blade with the point of a ball pen or something. Does the sound come back?

In fact, whenever I work on Crates or any other amp with those Cliff jacks, I ALWAYS measure the contact resistances. Look at the jacks. Ther is a blade running crosswise atop the plug when inserted. The plug lifts this blade. Ther is an extra contact the blade sits on when there is NO plug inserted. So with no plugs in any of them, measure resistance between the moving blade and the resting contact. It should read less than half an ohm. I am concerned for the tip contacts on the insert jack.

[bustamooooove]

I replaced the cliff jack with a panel mount jack, and ran wires from below the board to the jack above, so it would have clearance to mount to the panel.

I'm not sure how to measure resistance, but I picked up a multimeter yesterday so I will work on figuring that out.
Thanks for the advice!