Repair pointers always seem to be easier to remember or visualize when one is faced with an “eleventh hour repair”. I can’t say that there is one tip that can be globalized to all repairs; specific units, however, can have similar fault conditions that make repair pointers much easier to provide. Hence, the only advice that I can offer is to approach each repair with the same method.
Hope the following helps:
- Perform a visual inspection before you power up the unit (to see if there are any burnt components, etc.)
- Start trouble-shooting with the power supply section. Make sure you have all rails up and running. Is there a short from ground to the supply? If so, then check filter caps for shorts and transistor/regulator insulator inconsistencies.
- Break up the unit into three stages: a) input section; b) control section/filtering; and c) output section. If the unit has more than one channel, use the good channel as a reference for your repair.
- Never spend more than two hours on a repair at one time. Take a break or start another repair that you know you can finish quickly. Take the manual home at night and plan another repair strategy for the next attempt.
Paul Buchanan is chief technician at Contact Distribution, servicing amplifiers, processing devices and other professional audio equipment.