Troubleshooting - Digitech Multi Effects Pedal

[Thomas Davies]

Hi Guys, 

 

I've found a Digitech RPX400 multieffects pedal in a box of bits that was given to me years ago. It's ancient but in firing it up, the lights come on and the unit seems functional. 

 

Only problem is that the output is really dodgy, whether using Guitar, Bass or Uke (cables all tested and working fine), the signal cuts in and out constantly and there's intermittent feedback, either using a 1/4 output to an amp or the 3.5mm headphone jack to some earbuds. 

 

Is the unit toast or is it possibly the power supply? The one in the box seems to be for a broadband router/hub rather than the effects pedal (though it's still a 9V). 

 

Any other obvious troubleshooting tips? 

 

PS: My first post, looking forward to getting to know you all. 

[john]

Hey Thomas, have you opened the unit up?

[Thomas Davies]

On 7/23/2018 at 3:24 PM, john said:

Hey Thomas, have you opened the unit up?

 

I haven't, though I'm not sure I'd know what I was looking for if I did, any suggestions?

[john]

My suspicion is that the output circuitry is compromised, possibly with a cracked circuit board, or more likely a botched repair. It sounds similar to when the output jack has broken, one of the contacts has detached from the circuit board... and then someone has tried to solder it back on, and they have overheated the joint and the layers of the circuit board have separated. You then get pretty unpredictable behaviour. 

 

I suppose it is possible the output processing is malfunctioning somehow.

 

Neither is easy to fix, if at all. The only thing you could do is try, at least running some diagnostics. Do you have any understanding of electronics at all? Do you have a multimeter? You could source a circuit diagram.

 

The first thing would be to open the box and look at the circuit board. Look at the circuit board around the output connectors. Does it look like it has been re-soldered? It is likely to be obviously different soldering/ The circuit board may also look separated.

 

Another possibility would be, similar to the separated laters, the circuit around the output has actually lifted off the board (also a symptom of over heating.). You could post pics of top, bottom and side of the circuit board around the output block connectors.

 

Alternatively, put it into a shop and see what they say. It would be safer. Yes it would cost for them to look at, but not much. They can at least estimate a repair cost.