Ampex 351 Series - TROUBLESHOOTING AND REPAIR

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IOK 220n
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Microphone response set-up
Microphone Response
Connect an aud io oscillator as s hown in the
illus tration and make the response check by
sweeping the oscill ator t hrou gh the frequency
range to be chec ked.
NOTES ON ALIGNING
STEREOPHONIC EQUIPMENT
Stereophonic equipme nt , consisting of two
electronic assemb li es-a master and a slave.
and tw o track h ead assem blies, is aligned in an
a lm ost identica l fashion to th e monaural sys-
t
em by considering and aligning eac h amp lifi er
se par ately.
Certain s im ple diff ere nc es arc ou tlined for
the user's g uid ance. Before attempting align-
ment of th e two track stereophonic eq uipm ent.
note th e in st ru ct jon s for eac h ca tcgory.
Head Azimuth Adjustment
Because there are two h ea ds in each recor d
and reproduce stack. mak e th e a~jm uth adjus t-
m
ent for an average maximum meter indica-
tion, a
dju sting fir st one head and then the
oth er, and finally adjusting for the average
maximum met er indication.
This compromise azimuth adjustment ap-
plies to
reproduce a nd record heads alike.
When align in g the reco rd h ea ds. energ i ze th e
r
ecor d relays by d epressing the reco rd buttons
on each electronic assembly.
Record Alignment of Stereophonic Equipment
T reat each amplifier as though align in g
for sing le tra ck operation, and following the
instructions in th is section, proceed in this
sequen ce:
1. Cen t er the noise ba l ance ( sl ot parallel to
pl ane of t he c ha ss is face pan el if it is not
within 45° of center position) .
2.
Set th e ERASE AD JUST tr imm er for
proper indi cation .
7- 12
NOTE
When the MET ER and OUTPUT
SWITCH 'is in the ERASE position,
met:er
readings nmst be mad e with
on ly one amplifier i11 th e record mode
because, if both amplifie rs ar e record-
ing, false readings will be tah en.
3. Set the BI AS AD J UST trimmer for proper
indi cat ion.
4.
Set the record ca libr ation for proper read-
in g. R epea t on seco nd cha nn el.
Frequency Response
Frequency r esponse checks ca n be mad e on
both systems simultaneously. or the tracks can
be checked indiv idually.
Noise Balance Adiustment
Step 1: Position the number one amp lifier
RE CORD LEVEL knob fully counter-
clockwise.
Step 2:
Step 3:
Step 4:
Step 5:
Step 6:
Step 7:
Step 8:
Di sconnect any in put.
Place amplifier num b er one ONLY in
the record mode .
Plu g a set of ea rphones into the moni-
tor
jack and listen for the minimum
noise l ocat j on while ad ju sting the
noise b
alance control.
Stop t he recorder.
P
erform steps 1 and 2 on amplifier
number tw o.
Place amplific1·
number two ONLY
in the record mode .
List en for the point of minimum
noise whi le adjusting the noise bal-
ance contro l. Noise balance control
sl
ots should be wHhin 45 degrees of
a line paralleling th e face panel of
the chassis.
MAINTENANCE AND
TROUBLESHOOTING
General Maintenanc e Information
Faithful adherence to the recommended
ROUTINE MAINTENANCE found in SEC-