Common Solutions - Alesis HR-16 Service Manual

8.0 Common Solutions

A thorough knowledge of the software history can help solve a great many situations quickly.
Also be aware that with devices as full of options as the HR-16(B), there are even more possibilities
for user error (i.e. the user claims that MIDI out isn't working, but on checking the settings, the tech
finds that both MIDI clock, and DRUM NOTES OUT are turned off). Understanding how the user
has the unit in his (her) setup is an important tool in troubleshooting units that act like there is
nothing wrong with them.
While it is simply beyond the scope of this manual to present every possibility, the chart
below offers a majority of solutions to common situations.
Complaint
Unit is truly "dead". (No lights, or sound)
Unit powers up, but does not function. (No
LCD display, all LEDs on, buttons don't work,
etc.)
LCD shows no, or scrambled display (the rest
of the unit seems to function normally).
Intermittent reset.
Complaint
HR-16/HR16B Service Manual 1.00
Possible Cause
Blown power supply.
+5V rectifier blown (D5). (Note that 1N4001s
were used originally, but some were found to
be unreliable. We have since switched to
using 1N4004s exclusively.)
Blown DM3AG ASIC. (occasionally these
devices will "short" and pull down the 5V
supply rail)
Blown +5V filter capacitor (C5)
Usually blown capacitors
"distended" appearance.
Faulty or broken power jack.
Faulty or broken power switch.
Broken lead on power choke.
Blown monolithic filter capacitor. (Any of the
small blue RAM capacitors used as bypass
capacitors can become shorted and pull the
rail low. We are currently using ceramic disk
capacitors as replacements exclusively)
Unit is simply "crashed".
C-20 leaking excessively.
Faulty 8031, EPROM, or SRAM.
Faulty DM3AG ASIC. (Pulling down the 8031
data buss.)
Faulty I/O latch pulling down lines on data
buss.
Other faulty reset component.
Open or short in 8031 data buss.
Open or short in 8031 address buss.
Faulty LCD pulling down lines on data buss.
Faulty LCD.
Faulty LCD cable.
Faulty 74HC138 (U13), or open between U13
and LCD header.
C-20 leaking excessively.
Faulty 8031, EPROM, or SRAM.
D15 is glass package type (Revision A or CA
only).
R116 is pulling 8031 V cc too low (revision AQ
only).
Possible Cause
15
Replace and retest.
Troubleshoot and repair as necessary.
Remove ASIC and attempt power up. Also
note that this type of ASIC failure usually
causes the ASIC to become extremely hot to
the touch.
Troubleshoot and repair as necessary.
will display a
Troubleshoot and repair as necessary.
Troubleshoot and repair as necessary.
Troubleshoot and repair as necessary. (see
section 7.16)
Troubleshoot and repair as necessary. Note
that when these capacitors fail, they often turn
brown from overheating, and some will
occasionally just burn up.
Reinitialize memory and test.
Troubleshoot and repair as necessary. (see
section 7.13)
Troubleshoot and repair as necessary. (see
section 3.X)
Troubleshoot and repair as necessary.
Troubleshoot and repair as necessary. (see
section 3.2)
Troubleshoot and repair as necessary. (see
section 3.1)
Troubleshoot and repair as necessary. (see
section 3.X)
Troubleshoot and repair as necessary. (see
section 3.X)
Test with new LCD.
Test with new LCD.
Replace and retest.
Troubleshoot and repair as necessary.
Troubleshoot and repair as necessary. (see
section 7.13)
Troubleshoot and repair as necessary. (see
section 3.X)
Replace with metal package type (see section
7.2).
Add jumper across resistor.
Solutions
Solutions