j'ai trouvé en écrivant à digitech, ils me laissent dans mon caca, mais j'ai trouvé un magasin d'electronique qui me fera la répa!
c'est un problème officialisé par le fabricant!
"On occasion, a JamMan will exhibit a problem where the dry guitar signal will fade out while the playback remains unaffected. The problem in this case is an intermittent connection on pins 2 and 4 of the 40 pin ribbon cable between the top and main PCBs. While it is possible to replace the ribbon cable to fix this problem (new ribbon cables come from a different supplier), this is a very difficult job and can easily result in a damaged PCB. The following method also fixes the problem and does not require removing the top PCB from the chassis. It is necessary to remove the main PCB from the chassis.
Cut two pieces of 26 or 28 AWG solid (non-stranded) hookup wire; one 6.25” long, the other 5.5” long. Strip 1/16” off of all four ends of the two wires.
Solder one end of the longer wire to the rearmost pad (away from the jacks) of R145. Note this is an unused pad (R145 is omitted). Solder the other end to pin 2 of the ribbon cable on the top board. Pin 2 is a corner pin farthest from the USB jack.
Solder one end of the shorter wire to the end of R21 farthest from U18. Solder the other end to pin 4 of the ribbon cable on the top board (adjacent to pin 2 from the previous step).
It is important to route the new wires correctly so that they cannot pull off the board or pick up noise. Tack the wires to the PCB at the base of RC2 on the main board with hot glue or silicone glue. This should reduce stress from the surface mount pads the wires are soldered to. Tack the wires to the ribbon cable several times with hot glue or silicone glue to guarantee they stay positioned very close to the edge of the ribbon cable when the unit is reassembled."