User manual ALESIS HR-16 SERVICE MANUAL

[. . . ] HR-16/HR-16B Drum Machines Service Manual V1. 00 7/27/95 HR-16/HR16B Service Manual 1. 00 i 03/31/06 PREFACE This document is intended to assist the service technician in the operation, maintenance and repair of the HR16 and HR-16B Drum Machines. Together with the HR-16/B Reference Manual, this document provides a complete description of the functionality and serviceability of these machines. Any comments or suggestions you may have pertaining to the document are welcome and encouraged. READ THIS! In addition to any purchase price that Alesis may charge as consideration for Alesis selling or otherwise transferring this service manual ("Manual") to you, if you are not a service and repair facility ("Service Center") authorized by Alesis in writing to be an authorized Service Center, Alesis sells or transfers the Manual to you on the following terms and conditions: Only Service Centers authorized by Alesis in writing are authorized to perform service and repairs covered by an Alesis warranty (if any), and transfer of the Manual to you does not authorize you to be an authorized Service Center. Therefore, if you perform, or if the Manual is used to perform, any service or repairs on any Alesis product or part thereof, any and all warranties of Alesis as to that product and any service contract with Alesis for that product shall be voided and shall no longer apply for such product, even if your services or repairs were done in accordance with the Manual. [. . . ] To perform the internal diagnostics, connect a MIDI cable between MIDI in and out. Connect a 1/8 inch cable between Tape in and out. the order of items tested is: 1 ROM Test 2 RAM Test 3 MIDI I/O Test 4 TAPE I/O Test 5 LED Test 6 DAC Adjust 6. 3 DAC Adjustments The only adjustment necessary in the HR-16 is the DAC adjustment. This is normally done at the end of the HR-16's internal diagnostics, however holding the "PATT" button and pressing the "VOICE" button simultaneously also starts the DAC adjust routine. While this routine is running, adjust R90 (the trimpot near the PCM-54 DAC) so that a minimum of noise is heard during each drum hit. A DAC that is out of adjustment will "buzz", particularly at the end of the sample. Note that you may have to turn your amplifier up in order to hear this signal. Once the adjustment is complete, hitting the "STOP" button ends the DAC adjust routine. Tests EPROM for errors Tests SRAM for errors Tests MIDI input/output functions Tests Tape input/output functions Lights each front panel LED for a couple seconds Enters DAC adjust mode (press stop to exit). HR-16/HR16B Service Manual 1. 00 8 7. 0 Updates and Corrections 2N4401 Diagram 7 Diagram 6 7. 1 New SRAM Supply Circuit · All Revisions. The new SRAM supply circuit (See diagram 7) supplies a solid 5V to the SRAM, preventing input data from being higher in amplitude than the supply voltage, which can cause data corruption. First, remove the original diode (D8), then install the new circuit. Diagram 8 shows the location to install the circuit in Revision A & CA PC boards, while diagram 6 shows the location for revision AQ PC boards. The installation of this circuit is highly recommended, and is absolutely necessary if a 58257 SRAM is in the unit. This is because '257s are much more sensitive to supply voltage the older '256 SRAMs. · Diagram 8 7. 2 Glass Zener (D15) Revisions A & CA. For a short time, glass package 1N5231B zener diodes were used instead of the more familiar metal package. These were found to be unreliable, and should be replaced with metal package zeners. HR-16/HR16B Service Manual 1. 00 9 7. 3 Dirty Cliff jacks · All Revisions. Occasionally, oxidation will build up on the cliff jack contacts, causing the jack normaling to fail. When this happens, some drum sounds will be "lost" when using the unit in mono. The solution is to thoroughly clean the normaling contacts (See diagram 9 for location). Diagram 9 7. 4 Ground CE · All Revisions. It was discovered that many units returned for odd crashes all appeared to have a common component (National EPROMs). After further investigation it was revealed that it was not due Diagram 10 to defective components, but due to a minor "incompatibility". It was determined that using CE (pin 20) to enable the device took too long, and the 8031 would occasionally attempt to read it's instructions before the data was valid. [. . . ] 000000xxB 0xxxxxxyB 0yyyyyyyB 000nnnnnB | data | 00000000B F7H x: MSB of number of unpacked bytes of data after header y: LSB of number of unpacked bytes of data after header if y_0, then x=x+1 n: copy mode: 0=copy patt, 1-16=copy drum, 17=copy song The data is packed as 8 MIDI bytes per 7 data bytes as described above in the MIDI bulk dump explanation. This extra byte is required for proper operation EOX When transmitting any copy function, it is recommended that a pause of one second be inserted between the copy mode byte and the data that follows it to insure that the receiving HR-16 has enough time to move memory around to make room for the new pattern or song. In addition, it is recommended that a delay be added before sending additional MIDI commands, since it may take a few seconds for the copy operation to be complete, during which time MIDI data will be ignored. The amount of time required will be dependent on the length of the patterns or songs being copied, and the amount of free memory available. 06H STEP EDIT MODE This command is used to enter or exit step edit mode, as well as for stepping through the edited pattern. [. . . ]