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.
HR-16/HR16B Service Manual 1.00 15 Complaint Possible Cause Solutions Unit is truly "dead". (No lights, or sound) Blown power supply. Replace and retest. +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.) Troubleshoot and repair as necessary. Blown DM3AG ASIC. (occasionally these devices will "short" and pull down the 5V supply rail) 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. Blown +5V filter capacitor (C5) Usually blown capacitors will display a "distended" appearance.
Troubleshoot and repair as necessary. Faulty or broken power jack. Troubleshoot and repair as necessary. Faulty or broken power switch. Troubleshoot and repair as necessary. Broken lead on power choke. Troubleshoot and repair as necessary. (see section 7.16) 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) Troubleshoot and repair as necessary. Note that when these capacitors fail, they often turn brown from overheating, and some will occasionally just burn up. Unit powers up, but does not function.
(No LCD display, all LEDs on, buttons don't work, etc.) Unit is simply "crashed". Reinitialize memory and test. C-20 leaking excessively. Troubleshoot and repair as necessary. (see section 7.13) Faulty 8031, EPROM, or SRAM. Troubleshoot and repair as necessary. (see section 3.X) Faulty DM3AG ASIC. (Pulling down the 8031 data buss.) Troubleshoot and repair as necessary. Faulty I/O latch pulling down lines on data buss. Troubleshoot and repair as necessary. (see section 3.2) Other faulty reset component. Troubleshoot and repair as necessary. (see section 3.1) Open or short in 8031 data buss. Troubleshoot and repair as necessary. (see section 3.X) Open or short in 8031 address buss.
Troubleshoot and repair as necessary. (see section 3.X) Faulty LCD pulling down lines on data buss. Test with new LCD. LCD shows no, or scrambled display (the rest of the unit seems to function normally). Faulty LCD. Test with new LCD. Faulty LCD cable. Replace and retest. Faulty 74HC138 (U13), or open between U13 and LCD header. Troubleshoot and repair as necessary. Intermittent reset. C-20 leaking excessively. Troubleshoot and repair as necessary. (see section 7.13) Faulty 8031, EPROM, or SRAM. Troubleshoot and repair as necessary. (see section 3.X) D15 is glass package type (Revision A or CA only). Replace with metal package type (see section 7.2).
R116 is pulling 8031 Vcc too low (revision AQ only). Add jumper across resistor. Complaint Possible Cause Solutions