Motor Drive Amplifier
4840393
RTZ Professional Audio, LLC
2
1. INTRODUCTION
Thank you for purchasing your new RTZ motor
drive amplifier for Ampex MM-1200 studio
recorders! All cards are hand built and
individually tested prior to shipping. Before
installing the card, please read this document
thoroughly and retain it for future reference.
Additional copies of this manual are available
upon request or may be downloaded from our
website at
http://www.rtzaudio.com
.
All items are carefully packed to endure the
rigors of shipping and handling. However,
please inspect all contents and packaging
immediately upon receipt. Please report any
problems to us immediately. In the event of
damage, retain all shipping and packaging
materials for shipper damage claims inspection.
2. DESCRIPTION
The RTZ MDA (motor drive amplifier) replaces
the original Ampex MDA for the MM-1200 and is
designed for use in machines with three TO-3
motor driver output transistors on the MDA
heatsink chassis. The RTZ MDA is optimized to
work with the DTC-1200 digital transport
controller, but can also be used with the
standard Ampex transport controller as well.
The RTZ MDA includes torque offset adjustment
trimmers that allow fine adjustment of the torque
balance between reel motors. Balanced torque
offset is critical for use with the DTC-1200
controller.
The RTZ MDA torque offset is calibrated by
using the DTC-
1200’s zero torque adjustment
diagnostic feature. The offset trimmers are
adjusted until the motor just begins to develop
torque at a known reference DAC level. The
motor drive torque signal can be observed with
an oscilloscope connected to test points on the
MDA board as well.
3. WARNING! - ELECTRICAL HAZARDS
ARE PRESENT IN THE MDA AREA!
THE MDA CIRCUIT AND ASSOCIATED
COMPONENTS CONTAIN RECTIFIED AC
MAINS VOLTAGE. HIGH VOLTAGE DC IS
PRESENT
ON
THE
MDA
CARD
AND
EXTREME CAUTION SHOULD BE USED ANY
TIME MEASUREMENTS OR ADJUSTMENTS
ARE BEING MADE. WHEN INSTALLING OR
WORKING WITH THE MDA OR IT’S
ASSOCIATED
COMPONENTS,
USE
A
QUALIFIED SERVICE TECHNICIAN. ALWAYS
USE EXTREME CAUTION ANY TIME YOU
ARE WORKING WITH THE MDA CARD!
NEVER DIRECTLY TOUCH THE MDA CARD
OR ANY
OF IT’S PCB COMPONENTS WHILE
THE
BOARD
IS
INSTALLED
IN
THE
MACHINE. ALWAYS ASSUME THAT THE
MDA
BOARD
AND
ANY
OF
IT’S
COMPONENTS CONTAIN LIVE VOLTAGES
PRESENT
WHILE
INSTALLED
IN
THE
MACHINE!
USE EXTREME CAUTION IF THE MDA CARD
IS INSTALLED IN THE MACHINE ON AN
EXTENDER CARD! MAKE ABSOLUTELY
SURE THAT NO BODY
PARTS,
TOOLS,
TEST
CLIPS, WIRES OR OTHER
OBJECTS
COME
INTO
CONTACT WITH THE MDA
BOARD OR ANY OF
IT’S
COMPONENTS AT ANY
TIME!
A MOMENTARY SHORT TO THE CARD CAN
CAUSE SPECTACULAR ARC-AND-SPARK
ACTIVITIES AS WELL AS THE VERY REAL
POSSIBILITY OF DAMAGING THE MDA
CARD AND THE REST OF THE MACHINE!!!
DO NOT HOT SWAP THIS CARD! ALWAYS
REMOVE POWER BEFORE INSERTING OR
REMOVING THE MDA CARD FROM THE
MACHINE!!!
DISCLAIMER
THE USER ASSUMES ALL RISK BY
INSTALLING OR USING THIS MDA
CARD. RTZ PROFESSIONAL AUDIO,
LLC ASSUMES NO LIABILITY OR
RESPONSIBILITY FROM USING THIS
CARD. THE MDA CARD IS SOLD AS IS
WITHOUT WARRANTY AND WITHOUT
ANY MECHANTABILITY OR FITNESS
FOR ANY PARTICULAR PURPOSE.