Alesis A4/A8 Amplifiers Service Manual------ 9 03/07/03
3.00 Troubleshooting
The following chart is intended to help point a technician in the right direction.
Unfortunately there isn't space to provide an absolutely comprehensive list, however this should
help with some of the more common solutions.
Symptoms Probable Cause Solution
No Power (No LED, No Fan) Tripped breaker. Reset breaker.
Faulty breaker. Replace breaker.
Faulty transformer. Replace transformers and
retest.
Faulty A.C. Be sure that 30 amp service
is available without significant
voltage drop.
No output, no LED, Fan
running full on.
Fan board/Main harness
disconnected.
Reconnect and retest.
Faulty +15V regulator. Troubleshoot and repair as
necessary.
Clip LED on, no output. Blown output section. Replace all active
components following the
diver I.C. (U2-channel A U3
channel B) in blown channel.
Also replace any out of
tolerance resistors in the
output section.
Poor solder on the large
power supply capacitors.
(Causes ground reference to
drift).
Troubleshoot and repair as
necessary.
J1 or J14 loose. Reseat cable and apply hot
glue to prevent re loosening.
One channel out. Poor solder connections at
the Neutrik connector or the
high pass capacitors (see
section 1.20).
Troubleshoot and repair as
necessary.
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