Behringer GMX input PC board rebuild?

[Bonediggers]

I was given a Behringer GMX with a broken pc board—the one that holds the input jack. It was destroyed. They tried to change a broken jack. It appears that all the parts have values printed on them or the board. Has anyone tried creating a schematic and building a board from new components? There isn't that many. I'd like to give it a try for the helluvit. I really like the sound of these amps. I already have a working 210 so I don't need to do this. I just want to make something broken work again. Possible? I defer to your expertise.

Thanks in advance.

[Jazz P Bass]

Which model GMX?

How about a pic of the board.

[Bonediggers]

Which model GMX?

How about a pic of the board.

I've uploaded pics of each side. This is a GMX 110. Can the micro circuitry be replaced by standard resistors, caps, etc? If so I would have to mount the board remotely and run wires to the input jack terminals. Is this feasible? It's a cheap amp, but where better to learn? Thanks!

[Jazz P Bass]

GMX Input Circuit

In my opinion, you would be better off simply installing a new jack & running jumper wires to the proper connection points on the existing (albeit, bitched up) board.
I have attached a copy of the input circuit.
The proper jack must have the tip & ring with a normally closed contact.

[Bonediggers]

In my opinion, you would be better off simply installing a new jack & running jumper wires to the proper connection points on the existing (albeit, bitched up) board.
I have attached a copy of the input circuit.
The proper jack must have the tip & ring with a normally closed contact.

Thank you Jazz P for your input and pdf. Rewiring the existing board is my fall back position. I have a proper TRS jack with metal barrel/threads coming. I'm not sure all the paths on the board are functional. Continuity is easy enough to check but I was hoping to create something DIY while solving this problem. Is there a reason building a new board would not work, or be better? Thanks.

[MarkusBass]

Is there a reason building a new board would not work, or be better?

There is a simple reason for this: high cost of manufacturing 1 board only. If you want to check it, get KiCAD or similar software, design the board and order 1 pcs. If you order 20-30 boards, you will get them cheap but I assume you only need 1 pcs.
In my opinion the board that you have can be still used. All you need it to learn how to clean it, fix it (if this is needed) and solder back. It's easy but not everyone knows. It was described several times on this forum.

Mark

[Enzo]

Mark, the circuit is one JFET and a few passive parts. It is a source follower to buffer the input. One COULD just do without and wire the input straight into the amp like a zillion Fenders, but one need not go to all that engineering to make up a one transistor circuit on a bit of perf board.

[MarkusBass]

Mark, the circuit is one JFET and a few passive parts. It is a source follower to buffer the input. One COULD just do without and wire the input straight into the amp like a zillion Fenders, but one need not go to all that engineering to make up a one transistor circuit on a bit of perf board.

I know. I was referring to situation when the OP wants to have the board as it was originally. I know one could rebuild the board with an universal board, or even build it with point-to-point method. But in my opinion the old board could be easily fixed (at least I could easily do it).

Mark

[audiopete]

If it was me, I'd repair the board (its not destroyed IMO) with point to point jumpers, get the proper pc mount jack and re-use it. I wouldn't reinvent the wheel if I didn't have to. Then you don't have to deal with the quick connect terminals.

[gui_tarzan]

No, it definitely isn't destroyed. If it were mine I'd repair the traces, change the jack and put it back in. I understand wanting something to learn on but there's no sense in butchering a working amp and becoming "that guy".

Bonedigger, take the advice from someone who is still learning the build aspect (from some of the best teachers on the 'net right here) and start fresh with a simple amp circuit. That way you're not going to potentially kill a working amp if you make a mistake. I burned up a lot of ICs and LEDs back in the day before I caught on what NOT to do when building something. Yeah, sometimes I'm a little slow on the up-take but if I keep beating it into my head it eventually gets there.