Ampex 351 - Page 86

INPUT TRANSFER SWITCH
MIC
ERASE
HEAD
£
I
i
BALANCED BRIDGE
UNBALANCED BRIDGE
O
11
System block diagram
8-13
voltage to note aging of 6CR1. 3R60 may be
reduced in value or shorted out as rectifier ages.
Clean the relay contacts by inserting a piece of
high quality bond paper between contacts and
pulling it back and forth several times.
REPRODUCE
HEAD
2ND
AMP
STAGE
Troubleshooting the Reproduce Amplifier
A circuit for troubleshooting the reproduce
amplifier is shown below (see also — PARTS
3RD
AMP
STAGE
3RD
AMP
STAGE
OUTPUT
XFMR
89-0144
Issue A
1ST
AMP
STAGE
INPUT
XFMR
1ST
AMP
STAGE
4TH AMP
AND
OUTPUT
STAGE
PUSH-
PULL
OUTPUT
ERASE
ADJUST
RECORD
HEAD
4TH
STAGE
PHASE
INVERTER
BIAS
ANO
ERASE
OSC
BIAS
ADJUST
-M-
Corrective Maintenance
The first step in any corrective maintenance
procedure is localizing the faulty circuit. If a
tape recorded on the equipment itself docs not
reproduce correctly, the trouble can be in cither
the record or the reproduce circuit. In this case,
the faulty circuit can be identified by repro 
ducing a standard alignment tape or a commer 
cially recorded tape; if, while reproducing the
standard tape, trouble still exists the fault is
in the reproduce circuit, if the reproduce func 
tion is normal, the fault is in the record circuit.
A run through of the alignment and perform 
ance checks for the offending circuit will
further isolate the trouble or may rectify it,
and the faulty component or mechanical device
then should be identified easily.
2ND
AMP
STAGE
PUSH
PULL
OUTPUT
cy BIAS COUPLING
■O ; Mu-T.-TRACK
i OPERATION
Q
TION 6 TAPE TRANSPORT MECHANISM
and careful performance checks will insure
excellent equipment operation. When the
cleaning, lubricating and demagnetizing pro 
cedures arc followed as prescribed and the sys 
tem is set up according to the instructions in
this manual, equipment performance should
meet the high Ampex standards.
Neglect of maintenance procedures, such as
failure to clean the capstan, the head faces
and the tape guides daily can cause deficiencies
that are reflected in the amplifiers. For in 
stance, poor tape-to-head contact, due to tape
oxide accumulations, will diminish high end
frequency response.
Improper head azimuth adjustment will also
affect high frequency response.
When the user suspects faults, the above in 
formation should be considered, and, if satis 
fied that the cause is in the amplifier, he then
can begin troubleshooting.
Progressive Maintenance of the Amplifiers
Depending on equipment, check B+ voltage
at junction of 3R55 and 3R58 and make a
check of tube emission. Make sure tubes arc
returned to same socket. Check DC filament