Alesis QS7.1 Manuel de service télécharger pdf (Page 5)

Alesis QS Series Keyboards Service Manual V1.00 v 11/19/06

General Troubleshooting

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

electronics and basic troubleshooting techniques, a review of some of the techniques used by

our staff 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.

1 2 3 4 5 6 7 8 9 10 ... 96 97

Pas de commentaire

Alesis QS7.1 Manuel de service Page 5