Operating instructions

5.2 Routine Maintenance
This section covers routine maintenance procedures and a few parts
replacement procedures. See Section 6 for procedures on Alignments.
5.2.1 Removing and Reinserting the Printed Circuit Boards
The PCB Assemblies in the upper and lower card cages are equipped with
convenient levers that uniformly distribute pressure when withdrawing the
cards. Be sure to use the levers rather than pulling on the front lip of the
PCB Assembly shield plate. Grasp both levers by the ends closest to the
middle of the card and pull forward.
CAUTION: Before replacing PCB Assemblies, turn off the power first.
When replacing a PCB Assembly, observe that the PCB Assembly itself
protrudes beyond the metal shield plate. It is the PCB Assembly, not the
metal plate, that must be aligned with the upper and lower guides in the card
cage. Slide the PCB Assembly in carefully, and then press firmly on both
levers to seat the PCB Assembly fully home into its mating connector.
It makes no difference whether any of the PCB Assemblies in the upper cage
(AUDIO PCB Assemblies, cards #1-24) are exchanged with one another; they
are numbered for convenience so that once aligned to a given head assembly
several PCB Assemblies can be removed and reinstalled to the same position,
eliminating the need to realign the machine.
5.2.2 Hour Meter
The Hour Meter PCB Assembly is located under the transport between the
reel motors. To gain access to the Hour Meter, lower the VU Meter Panel and
open the Transport. The total amount of time the MTR-90III is in Load, Play
and Record, and Fast Wind (F.FWD and RWD) modes is indicated on the
Hour Meter PCB Assembly.
LOAD Load mode
PLAY,REC Play and Record modes
FAST Fast Wind modes (Fast Forward and Rewind)
CAUTION! Do not close the Transport while the VU Meter Panel is closed.
Closing the Transport while the VU Meter Panel is closed will cause damage
to the shield motor.
MTR-90III Operation and Maintenance Manual
October 1990
Section 5 Maintenance
5 - 5