Alesis MicroVerb Service Manual page 10

8.0 Troubleshooting and Repair
Described Symptom
Unit is completely dead. (No lights, no effects).
Unit turns on, but no effects.
LED stays green no matter what.
LED stays red no matter what.
Distorted effects.
Noise when switching effects.
Intermittent effects.
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MicroVerb/MicroVerb II Service Manual 1.00
Possible Causes
Faulty Power supply.
Faulty P.S. jack.
Faulty +5 volts.
C23 is leaking.
Faulty ASIC.
Faulty DAC.
Faulty 4053.
C13 is leaking.
C16 is leaking.
Faulty ASIC
Problem with LSTMSB line. (This will usually be
noticed as a DC offset in the signal at U14 pin
7).
Failure in power supply section (+ or - 12V rail
is bad).
Faulty or wrong type 4053 (This can cause a
DC offset at the input to the comparator [U8 pin
3]).
Faulty ASIC.
Faulty DRAM(s).
Faulty DAC
Input sample capacitor is leaky.
Goldstar 7404s.
Faulty shaft encoder.
C23 leaking somewhat.
Faulty shaft encoder
Bypass jack normaling contact is dirty.
6
Solution
Replace supply and retest.
Replace and retest.
Troubleshoot and repair as necessary.
Replace and retest.
Troubleshoot and repair as necessary.
Troubleshoot and repair as necessary.
Troubleshoot and repair as necessary. (See
also section 6.7).
Replace and retest.
Replace and retest.
Troubleshoot and repair as necessary.
Troubleshoot and repair as necessary. (See
also section 4.1).
Troubleshoot and repair as necessary.
Troubleshoot and repair as necessary. (See
also section 6.7).
Troubleshoot and repair as necessary.
Troubleshoot and repair as necessary.
Troubleshoot and repair as necessary.
Troubleshoot and repair as necessary.
See section 6.8.
Replace and retest.
Replace and retest.
Replace and retest.
Troubleshoot and replace if necessary.
3/7/2003