Alesis A6 Service Manual download pdf (Page 16)

Confidential Alesis Service Manual 8-31-0089-C

3.1 General Troubleshooting

While this manual assumes that the reader has a fundamental understanding of electronics and

basic troubleshooting techniques, a review of some of techniques may help.

° Visual Inspection - A short visual inspection of the unit under test will often yield results

without the need of complex signal analysis (burnt, or loose components are a dead

giveaway).

° Self Test - Alesis products that utilize microprocessor control contain built in test

software which exercises many of the units' primary circuit functions. Self test should

always be done following any repair to ensure basic functionality.

° Environmental Testing - Applying heat and cold (heat gun/freeze spray) will often

reveal thermally intermittent components (Clock crystals, I.C.s, and capacitors are

particularly prone to this type of failure).

° Burn in Testing - Leaving a unit running overnight often reveals intermittent failures

such as capacitors that begin to leak excess current after a significant amount of time.

° Cable Checks - Wiggling cables can reveal intermittent failures such as loose cables or

poorly soldered headers. Remember to check power supply cables as well.

° Flexing the PC Board - Poor solder joints and broken traces can often be found by

pressing the PC Board in various places.

° Tapping Components - Sometimes tapping on a component (particularly crystals) will

cause it to fail.

° Power Down/up - Turning the unit off and back on rapidly several times may reveal odd

reset and/or power supply failures.

° Reset Threshold - A Variac (variable transformer) can be used to check reset threshold

levels. This can be particularly useful in helping customers with low line problems.

° Compressors - Using a compressor/limiter is often helpful when attempting to solve low

level noise problems, as well as assisting with DAC adjustments.

° Sweep Tests - Sweep generators are very useful in checking the frequency response

envelopes of anti-aliasing filters.

° Piggybacking - Piggybacking I.C.s is particularly useful when troubleshooting large

sections of logic. This is especially true when working with older units.

° Assembly/Disassembly Organization - When removing assemblies, organize screws

and clips with the assemblies that they were removed from. Organizer trays save a lot of

time during re-assembly since similar screws and clips will not be mixed with each other.

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Alesis A6 Service Manual Page 16