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. [. . . ] The threshold detection circuitry surround U1C is relatively straight forward. R14 and R15 establish the threshold level with R12 and C9 acting as a filter to stabilize the threshold level and prevent oscillation. R21 establishes some hysteresis and R13 is a pullup for the open collector output of the LM339. The output of the '339 is sent directly to the 8031 in the form of an interrupt line. Forcing the 8031 to respond immediately to tape input is necessary due to the timing constraints required for I/O (especially in tape sync situations). 6. 0 Test Procedures If possible, user data should always be saved (DataDisk, or equivalent, recommended) prior to servicing. While this may not be immediately possible (or possible at all), it should be attempted as soon as possible. HR-16/HR16B Service Manual 1. 00 7 6. 1 General Testing General testing should, at a minimum, consist of self test, and a short audio test (including testing key response and recording and playing back a pattern). More extensive testing would include: Checking battery backup Actually sending and receiving MIDI information Saving and loading data from tape Copying full patterns to themselves, then to other patterns so that memory becomes completely full (this ensures that the 8031 address buss functions correctly, as the self test does not take addressing into consideration). 6. 2 Internal Diagnostics and Hidden Keys Below is a list of the key presses necessary to activate hidden functions. Power up while holding "ERASE", "DELETE", and "RECORD"------------Clear memory/Reinitialize system. Power up while holding "QUANT" and "MIDI UTIL"---------------------------Self test. Hold "PATT" and press "VOICE"--------------------------------------------------DAC Adjust mode (press "STOP" to exit). Be aware that the self test will erase all internal memory (equivalent to reinitializing). To perform the internal diagnostics, connect a MIDI cable between MIDI 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. 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. [. . . ] If the command is to copy a drum, the drum number sent in the mode byte (-1) will be copied to the drum button hit within 3 seconds of receiving this command, otherwise it will be ignored. 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. [. . . ]