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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 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 (Playback).....................................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 considerations.....................................................19
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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 programming
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 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 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 the 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)
Initialization
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, 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.
