Behringer v-tone GMX212, fx board damaged, remove and bypass instructions

[hozone]

hello,

i've buy a damaged gmx212 for a few euros.

the dsp fx board was damaged, sometimes it display the "d2" error, sometimes just make the audio signal buzz, or do not work nothing.
voltages seams ok, ic and components seams all ok and the dsp.
i've scope around but i can not find anything wronk (i'm a software developer with electronics hobby, i'm not a pro here), so i've decided to remove this board and bypass the dsp.

i've found schematics here: BEHRINGER GMX1200H - Electrónica - Esquemas - TV - Áudio - Digital

the dsp board control the signal path, using the two 4053, IC8 to control "insert" signal, IC9 to control channel 1/2 selection.
to remove the dsp board we have to control the 4053.

IC8 must let the signal flow from pin 4 to 3, and from 14 to 13, because i want to bypass the dsp.
IC7 must let the signal flow according to a channel selection.

solution step:
1) pin 13 of x27 connected to a 10k resistor (optional), to put 5v on the 4053 ABC circuit control.
2) pin 13 of x27 connected to pin 20 to put ABC of IC8 high, and bypass the dsp board insert signal.
3) pin 24 of x27 connected to GROUND or disconnected from GROUND to select channel 1 or 2, i've used a switch and removed the sw9 to use the sw9 hole.
4) optional: connect a mono jack to the new switch selector to use an external pedal for channel selection.
5) put damaged dsp in litter basket

hope it will help.

p.s. sorry for my english

[hozone]

correction: the optional resistor on solution step 1 should be a 1k resistor not 10k

[wblakesx]

My gmx 210 ust gave up- switching channels only intermittently available (depending on unplugging or ust repowering by power switch... abit complicated as it is a variable effect); no signal except briefly when switching channels or effects (sounds for about 1/4 second when the effects or channel select works at all).
I need to study the diagrams and open up the amp. Back later.

perhaps some help here: http://music-electronics-forum.com/t21673/

[f4t_p]

Hi, I too am having troubles with this amp. I don't suppose anybody knows what the part is called for the potentiometer labelled SW2 (The FX Pot)? I have 2 broken pots and am in the middle of replacing them, but I don't for the life of me know what to order. I also need the presence pot (VR12) but think I may have found this (50k audio potentiometer from RS Components). Thanks in advance good people!