Troubleshooting - Alesis MIDIVERB IV Service Manual

8.00 Troubleshooting

This chart is presented in the interest of helping technicians new to our product line. It is
not intended as a substitute for genuine troubleshooting.
Observed Problem
No power, unit is "DEAD".
Lights up, but no display or function.
Unit locked up (display works but unit
doesn't function).
Garbled LCD display.
No audio.
No effects (wet) output.
Distorted output.
Noisy audio.
No MIDI in.
No MIDI out.
Alesis MidiVerb IV Service Manual'
Possible Cause
Faulty power supply.
Faulty +5V rectifier diode (D2).
Faulty bypass capacitor.
Faulty 8031.
Faulty SRAM.
Unit "crashed".
Faulty M4 ASIC.
Faulty LCD Module.
Loose front panel cable.
Faulty 8031.
Unit "crashed".
Faulty SRAM.
Faulty LCD Module.
Faulty 8031.
Faulty M4 ASIC.
Faulty ADC.
Faulty DAC.
Faulty DIGPOT.
Faulty M4 ASIC.
Faulty 8031.
Faulty DIGPOT.
Input levels set too high.
Faulty ADC.
Faulty DAC.
Faulty or wrong power supply.
Power supply circuitry bad.
Faulty op-amp.
Faulty M4 ASIC.
Faulty ADC.
Faulty DAC.
Faulty opto-isolator.
Faulty 8031.
Faulty 8031.
8
Possible Solution
Replace and retest.
Test diode, replace if necessary.
Check for burnt or hot capacitors. Replace if
necessary.
Replace and retest.
Replace, reinitialize memory (Power unit up
while holding "A" and "D") and retest.
Reinitialize memory and retest. (Power unit
up while holding "A" and "D")
Replace and retest.
Test with known good front panel. Replace if
necessary.
Reseat cable and retest.
Replace and retest.
Reinitialize memory and retest. (Power unit
up while holding "A" and "D")
Reinitialize memory and retest. (Power unit
up while holding "A" and "D")
Test with known good front panel. Replace if
necessary.
Replace and retest.
Replace and retest.
Troubleshoot and repair as necessary.
Troubleshoot and repair as necessary.
Troubleshoot and repair as necessary.
Replace and retest.
Replace and retest.
Troubleshoot and repair as necessary.
Reduce input levels and retest.
Troubleshoot and repair as necessary.
Troubleshoot and repair as necessary.
Replace and retest.
Check regulator outputs and troubleshoot as
necessary.
Troubleshoot and repair as necessary.
Replace and retest.
Troubleshoot and repair as necessary.
Troubleshoot and repair as necessary.
Replace and retest.
Replace and retest.
Replace and retest.
03/05/99