Oberheim Prommer Service Manual 电路图.pdf

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1、Prommer Service Manual 1 Oberheim Prommer Digital MIDI Sampler / PROM Programmer SERVICE MANUAL Paul J. White 1986 Oberheim A Division Of ECC Development Corporation 11650 West Olympic Boulevard, Los Angeles, California 90064 Oberheim, the Oberheim logo and Prommer are trademarks of ECC Development

2、Corporation. RadioFans.CN 收音机爱 好者资料库 Prommer Service Manual 2 Table of Contents Introduction . 3 Power Supply Adjustment. 3 Initialization . 3 Test Programs. 4 Display Intensity. 4 Memory Test. 4 Display test. 5 Sine wave test . 5 VCC Supply test . 5 VPP Power supply test. 6 Relay Test . 6 PROM data

3、 test. 6 Battery replacement. 7 Circuit description. 7 Power supply. 7 Programmable power supplies . 8 Battery backup. 8 RESET circuitry . 8 Microprocessor and memory . 8 Clock and timing circuitry. 9 MIDI interface . 9 Audio input. 10 Analog to digital converter . 10 Digital to Analog conversion (P

4、layback) . 11 Reference voltage generation. 11 Vacuum Fluorescent Display. 12 EPROM Programming circuitry. 12 Switch Matrix . 13 LED audio level meter . 13 External Trigger Input. 13 Prommer 6809 Programming Reference. 14 Interrupts . 14 Memory. 15 Memory Map of the Prommer. 15 Programming considera

5、tions. 19 RadioFans.CN 收音机爱 好者资料库 Prommer Service Manual 3 Introduction This manual is divided into two sections. The first section is designed to assist the service technician in testing and troubleshooting the Oberheim Prommer MIDI Audio sampler / PROM programmer. The second section is a programmi

6、ng reference for the Prommer for those who wish to write application programs for the Prommer. The reader should have a basic knowledge of electronics and microprocessor systems, and be familiar with standard repair techniques. Power Supply Adjustment The first step in testing is the calibration of

7、the +5 volt power supply. This is the only adjustment necessary for correct operation. Open the unit by removing the two screws under the front edge and lifting the front panel open. With AC power ON, connect the common lead of a DC voltmeter to ground and probe the +5 volt test point (the lower end

8、 of resistors R81 and R82). Now, adjust the trimmer VR1 (near the upper right corner of the processor board) until the measured voltage is 5.00 volts +/- 10 millivolts. You may verify the correct operation of the other power supply voltages on the processor board now. There are no adjustments for th

9、e other supplies, but they should be within the specified ranges. Voltage Test point location +12v +/- 600mv Pin 4, U18 (TL084) -12v +/- 600mv Pin 11, U18 (TL084) -5.1v +/- 500mv Pin 7, U14 (4051) -35v +/- 5 volts D7 anode +35 volts +/- 5 volts Q1 collector -4.1v +/- 100mv Pin 1, U9 (TL082) Initiali

10、zation The first time the unit is powered up, the RAM will contain random data. The display will read CHECK BATTERY if the unit has never been initialized or if a memory loss has occurred. To clear the CHECK BATTERY message, initialize all system and block variables and erase all sound storage RAM,

11、turn the unit off, press and hold the CLEAR key, and turn the power back on. Continue holding the CLEAR button until the display lights. RadioFans.CN 收音机爱 好者资料库 Prommer Service Manual 4 Test Programs There are eight test programs built into the Prommer. To access the test programs, hold down the PLA

12、Y and RECORD switches while turning on the AC power. The display should read “TEST PROGRAMS” until the switches are released, and then will display the first test. To skip over any test in the sequence, just press the STOP switch. Display Intensity Display reads: DISPLAY INTENS. . . The arrow button

13、s are used to increase or decrease the brightness of the display. After the display intensity is at an acceptable level, press the STOP switch to access the next test. The brightness will remain set at this level until an ERASE ALL, or power-on erase command resets all memory. Memory Test Display re

14、ads: MEMORY TEST *. Press EXECUTE to start this non-destructive RAM test. The display should read BUSY for about 15 seconds and then if there are no errors in the 64K of data storage memory, the display will read OK. If a memory error occurs, the address of the first bad location will be displayed.

15、To locate a bad RAM chip use the following table. IC number Address range U46 0 8192 U47 8192 16383 U48 16384 24575 U49 24576 32767 U53 32768 40959 U54 40960 49151 U55 49152 57343 U56 57344 65535 Press STOP after the memory test is complete to go to next test. Prommer Service Manual 5 Display test D

16、isplay reads: DISPLAY TEST *. Press EXECUTE to start the display test. The letters A through Z will be displayed in all sixteen character positions in repeating sequence until the STOP key is pressed. Press STOP to end the display test. Sine wave test Display reads: 440HZ SINE WAVE *. Press EXECUTE

17、to start the sine wave test. A 440HZ sine wave will be generated using the Prommer digital to analog circuitry. An amplifier and speaker connected to the Line Output can be used to monitor the output for distortion or an oscilloscope may be used to check the waveshape. The amplitude of the wave at t

18、he output should be about 7 volts peak-to-peak. If the frequency of the wave is not 440.0Hz, there may be a problem with the sample rate generator, or the master clock oscillator. Press STOP to access the next test. VCC Supply test Display reads: VCC SUPPLY TEST *. This test and the next one are use

19、d to verify the operation of the programmable power supplies used for EPROM programming. Make sure the EPROM socket is empty before continuing. Press EXECUTE to start the test. Connect a DC voltmeter to pin 14 (ground) and probe pin 28 of the EPROM socket on the front panel. (Note: pin 14 is located

20、 at the lower left corner of the socket, pin 28 is at the diagonally opposite corner and pin 1 is at the top left corner.) Now, the measured voltage should be within about five percent of the voltage displayed on the Prommer front panel (see the table). Use the arrow switches to make the voltage (di

21、splayed in millivolts) go up or down. You may press the “9” switch to set the voltage to its maximum value, or press the CLEAR switch to reset the voltage to zero. The VCC supply should be test at several points including zero volts, five volts (4992 millivolts) and six volts (6016 millivolts). Pres

22、s STOP to go to the next test. VCC test voltages (pin 28) Displayed Minimum Voltage Reading Maximum Voltage Reading 0 -0.05 +0.05 4992 4.75 5.25 6016 5.70 6.30 Prommer Service Manual 6 VPP Power supply test Display reads: VPP SUPPLY TEST *. Press EXECUTE to test the high voltage programmable power s

23、uplly. Connect a DC voltmeter to pin 14 (ground) and probe pin 1 of the EPROM socket on the front panel. Use the arrow switches to change the voltage. Voltages should be within about five percent of the displayed value. Test the VPP supply voltage at zero volts, twelve volts (11978mv), and twenty-fi

24、ve volts (25016mv). Press STOP to go on to the next test. VPP test voltages (pin1) Displayed Minimum Voltage Reading Maximum Voltage Reading 0 -0.05 +0.05 11978 11.5 12.5 25016 24.0 26.0 If an oscilloscope is available, check the rise and fall time of both power supplies as you toggle between zero a

25、nd the maximum voltage. The rise and fall times should be less than 100 microseconds and there should be no more than 0.5 volts of overshoot. Also check the waveforms for ripple or oscillation. There should be no more than 100mv of ripple on either power supply at any setting. Relay Test Display rea

26、ds: RELAY TEST *. Press EXECUTE to turn all relays in the EPROM programming circuitry on and off repeatedly. You should be able to hear the three relays clicking on and off in a steady rhythm. Press STOP to end the relay test. You may need to hold the STOP switch for a second before the Prommer will

27、 respond. If the display still reads RELAY TEST, press STOP again to go to the next test. PROM data test Display reads: PROM DATA TEST *. Press EXECUTE to start the test. Display will then read BUSY. The PROM data test toggles all address and data lines connected to the EPROM socket on the front pan

28、el. An oscilloscope or signature analyzer is required to complete this test. Pressing STOP will now return control to then normal Prommer power-on sequence. Prommer Service Manual 7 Battery replacement The static RAM is powered by a lithium battery when the AC power is off. The battery will require

29、replacement occasionally (normal battery lifetime should be at least one year typically much longer). The battery is a three volt BR-2032-1HB or equivalent. To replace, disconnect the Prommer from its source of AC power and open the unit by removing the two screws securing the front panel. The batte

30、ry is located on the right side of the lower printed circuit board near the front and may be unsoldered and replaced without removing the circuit board. Be careful not to short circuit the battery during removal or replacement and carefully observe correct polarity. The positive terminal of the batt

31、ery should connect to the pad on the right. After installing a new battery, check the standby current drain by connecting a voltmeter across the 1k resistor in series with the battery (R141). Measure the voltage drop and divide the voltage reading by 1000 to obtain the actual current drain. Normal c

32、urrent with power off should be less than 20 microamps (voltage reading of .020 or less). It is not unusual for some units to have a battery current drain that is too low to measure. Circuit description Please refer to the schematic diagram pages indicated. Signal names are shown in capital letters.

33、 Names followed by an asterisk (*) are active low logic signals. Others are active high logic signals or analog signals. Power supply (Processor schematic page 3) The +5 regulator and the VCC programmable regulator draw power from one of two transformer secondaries through rectifier D9 D12 and filte

34、r capacitor C69. The +5 regulator consists of active components U34 (LM723) and Q8 (D880 or 2N3055) and is adjustable with the 1k trim pot. The other transformer secondary supplies power to the +12v and 12v regulators through D15 D18, filtered by capacitors C49 and C50. A voltage doubler consisting

35、of C57, C74, D13 and D14 supplies +35 volts for the VPP programmable regulator. Another voltage doubler (C67, C68, D7 and D8) supplies the negative voltage for the vacuum fluorescent display. A zener diode (D1) and resistor (R43) tap the 12v supply to provide the 5v source for the analog switches U3

36、, U4, and U14. Prommer Service Manual 8 Programmable power supplies (Processor schematic page 3) Various voltages required by different types of EPROMs are generated by two programmable power supplies. Half of U36, Q1, Q3, Q4, and Q6 are the active components in the VPP supply. VPP has a range of ze

37、ro to +27 volts, the output controlled by the reference voltage VPPREF which is produced by a digitally programmed DAC/sample/hold circuit. The supply circuit is current limited and has a voltage gain which is determined by R93 and R94. Digital signal VPPSEL* must be at logic zero to enable the VPP

38、supply. The other half of U36, Q2 and Q5 make up the VCC programmable supply which has an output range of zero to +8 volts. The gain of the VCC circuit is determined by R97 and R99. VCC is also current limited and the circuit is enabled by a logic zero on VCCSEL*. Battery backup (Processor schematic

39、 page 3) In order to retain the contents of memory at all times, a three volt lithium battery supplies power to the CMOS RAM through R141 and D26 when the main power is off. When the power is on, the +5v supply powers the RAM through D25. RESET circuitry (Processor schematic page 5) The PUP (Power UP) circuitry consisting of active components Q10 and U65 disables writing to