Digitech GSP1101 Effects Processor Repair

A frantic spouse called to explain that she was vacuuming and hit this ‘thing’ and broke this little piece off it.  Could I fix it before her husband found out?  The Unbrokenstring Crew to the rescue again!

01GSP brokenThe gain knob on this unit is a rotary encoder.  This component is available from several vendors.

02GSP what to doShe kept the knob, which is GREAT news, because although the rotary encoder is available, the knob is not.

03GSP salvage knobThe remains of the shaft of the rotary encoder was removed from the knob.  So far, so good.

04GSP opensesameLet’s get to work replacing the broken rotary encoder.

05GSP knobs offAs is the usual case, all the knobs come off first.

06GSP board looseThe circuit board lifts away easily.

07GSP spacer1These cool little plastic spacers set the geometry of the rest of the buttons and controls.

08GSP spacer2We will put this piece away somewhere safe while work elsewhere continues.

09GSP remove oldTo minimize the stress on the circuit board while removing the old component, the body of the broken rotary encoder is cut away from the component leads at an angle perpendicular to the circuit board.

10GSP part goneWith the component cut away from the circuit board, de-soldering the legs becomes trivial.

11GSP clear backThe component legs are gone.  This is a high-quality circuit board, double-sided copper and plated-thru holes.

12GSP clear frontBoth sides of the circuit board are cleaned up.

13GSP new partHere is the new part, ready to be soldered onto the circuit board.

14GSP reassemble1We are ready for reassembly.  That plastic spacer is re-installed as it was before.

15GSP reassemble2The cable carries all the signals back and forth to the front panel.  I like this bit of orgami.

16GSP reassemble3The circuit board is held in place by the bodies of the controls, which are in turn bolted to the front panel.

17GSP knobs onEverything is back together, ready for testing.

18GSP power onThis looks good!  While we were at it, we will do a factory reset.

19GSP final testNow, everything is as it once was.  And the husband was scolded for leaving his toys on the floor, where she could hit them with the vacuum.  Maybe I could sell him a rack case?

Thanks for reading all the way through!

CONTACT – David Latchaw EE