Repairing

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A NiCd battery that has leaked in a Korg Poly-61, corroding traces and IC legs.
Two broken solder joints (left) and a delaminated PCB trace (right).
Failed electrolytic capacitors with swollen can tops and expelled rubber.

Repairing electronic music gear includes troubleshooting problems, replacing worn or damaged parts (both mechanical and electronic), repairing electrical connections, and performing preventive maintenance.

Prophet 5 rev. 2 missing a power transformer.

Essentials of electronics repair

Be Careful
Avoid causing more damage.
Be organised and take your time.
Start simple
Check easy-to-fix issues first.
External checks
Gather information on symptoms.
Check cables, power supplies and fuses.
Look for signs of physical damage.
Cleaning
Brush and vacuum the device with ESD-safe methods.
Remove contaminants e.g. from spilled drinks
Opening the device
Unplug gear before opening.
Use soft surfaces to avoid scratches, ensure any separated but still connected parts are well supported.
Find the service manual (these can have errors)[1] or watch disassembly videos.
Use containers to keep screws and other fastenings from getting lost.
Take note of where any parts will go when reassembling.
Take detailed photos of the internal setup, you may need to refer to these later.
Initial observations
Check for battery leakage, physical deformities, and blown fuses, (look for the cause of any blown fuse).
Look for signs of overheating or smoke.
Connections between dissimilar metals can corrode or degrade over time.
Fixing process
Re-seating connectors can solve many issues. Be very careful not to bend any pins.
Check for corrosion and clean with contact cleaner.
Avoid fully removing socketed ICs fully; raise the IC slightly and push down again to clean the contacts.
Clean or replace scratchy pots.
Check solder joints and touch up if needed, (with matching solder type). Be careful not to damage any nearby wires plastic parts with the iron.
Common issues
Many problems are mechanical rather than electronic.
In industry when fixing is too time consuming a board is swapped rather than repairing the components.[2]

Showcase

Practical, real-world examples to guide and inspire.

See also

Methods

References

  1. ^ Re: Duplicating old PCBs... strategies? tips?, Mod Wiggler Forum, 6 Oct 2020
  2. ^ How to fix electronic music gear by by Craig Anderton, Harmony Central, 13 Feb 2017

Further reading

  • How to diagnose and fix everything electronic by Michael Jay Geier, McGraw Hill TAB, 2015, ISBN 9780071848305
  • Troubleshooting and Repairing Electronic Music Synthesizers by Delton T. Horn, TAB, 1992, ISBN 9780830639212, (not recommended)
  • Prophet 5 technical manual by Sequential Circuits

External links

Forums

Facebook

YouTube

About the general principles. For repairs to a specific piece of equipment, see its page.

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