Chapter 18, Maintenance and Troubleshooting
ALESIS M20 REFERENCE MANUAL 1.06 18-5

CHAPTER 18

MAINTENANCE AND
TROUBLESHOOTING
Under no circumstances should you remove the top or bottom cover
of the M20 unless you are a qualified and careful technician. It is
possible to damage your heads and other sensitive parts of your
ADAT whenever the cover is open. Do not open up your ADAT to
clean the heads unless you are experienced in MDM or VCR
maintenance, have the approved tools and materials, and follow all
safety procedures.

18.1 ADAT HEAD CLEANING

The most common cause of problems in playback or recording is dirty heads.
Depending on the quality of the tapes used and the environmental conditions where the
M20 and its tapes are stored, head cleaning will eventually become necessary. In
typical professional applications where many different tapes are used, a complete
head cleaning is recommended every 100 to 250 “drum on” hours, or whenever the
error rate (shown on Utility menu #20) begins to climb with a tape that is known to be
good (see section 4.11, “Recording a Benchmark Tape”).
To display the number of hours the head has been against the tape, hold PEAK
CLEAR and press STOP.
Note that due to the error correction process built into the M20, the actual sound quality
of an ADAT recording will not be affected unless there is quite a bit of dirt on the heads.
If the ERROR indicator (in between the two counters in the display) flashes on a
regular basis, even on newly-formatted tapes, we recommend that you bring your
M20 to an authorized Alesis Service Center for cleaning. If the indicator is not
appearing and the unit is performing normally, there is no reason to clean the heads.
Periodic or preventative maintenance on the M20 is NOT required as often as it is on
analog or video decks; in fact, overdoing it may cause premature wear.