Marantz 2 Service Manual

Page 1

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The perforated protective grille is held in place by Emir spring clamps. It can
he removed. nest euily with a light eastward pull. on it's hottan edges. Do not
attempt to pry slang top or sides with tools or amaze to the finish may result.
Remve all protective packing around the tubes and. replace grille ether carefully
positioning flush with tap and sides. A little pressure nu]. snap it hack into
nlsce.

Input and output cables may be attached and dressed am the tram: and under the
amplifier where it can then be led out the beck. The grille will then hiss all
wires, tubes, etc.

0mm m values :

117 Volts, 60 cycles (for 11.0. operation only). All specification are based. on
this voltage. The usable range 15 mm 105 to 125 volts, 50-60 cycles.

INF!!! CONNECTIONS:
There is a choice of three input connections to the Hammer Pane: amplifier;

1.- PREAMP- This input is reccmmemed for most preslnpiltiers.
A1; this connection a 2 volt sigaul will drive the
Amplifier to it's mu output. A subsonic filter
runs at! frequencies below 20 cycles so as to
supress speaker "breathing" and other subsonic dis-
turbanees.

2.- mm GAIN, nm- For preamplifiers cut have s law out-
pm: Voltage capability. Also my be used. where
loudspeaker has very low efficiency. A signal or
0.7 volts is required here for full ho watt output.
subsonic filtering is also in effect.

3.- HIGH GAIN, W- Same an above in sensitivity but
without the subsonic filter, response being maintained
to helm 2 cycles. This imam: is direct to the in-
put grid and is used in testing frequency response
or for special applicabinns where aubsnrdc response
is needed.

OUTPUI WIDNS:
when not using Variable Damping:

l..- Use "Ground Return" (center terminal.) on land. speaker ant-
puf. terminal strip together with impedmce tap on
right which watches speaker.

2.- Variable Denying control must be switched of! tar yroper
uperstion. -

To Use Variable Designs:
L- Instead of usual ground return, connect to correspuxmng
"Variable Damping Return".
For Exsmle: An 8 Ahm speaker will hsve one lead on the
8am tn}: 1:0 ugh: am the other on 128 tap to the left.
2.- Tum Weriebls Damping" control. on end unjust to desired
semi-DB factor.

M WAIT-20 um sun-ox:
This unit has been designed primarily an a 1&0 watt uleruinesr Amplifier. maker

systems of a lever paler rating could euiLv be damaged by unwanted. pulses caning
thrwgh at full power. To protect these systems we have incorporated I switch

Page 2

which changes the nutyut connections to Triode operation limiting the punter output
to 22 or 23 watts. This control, lunar-ed near the cum terminal strip, is
marked "ho Watt UL" and. "20 watt. m".

m EMS and W5:

Bach Amplifier is euemlly adjusted at the rectory for proper operation. Never-
mlese the mt should check the operating conditions after 15 minutes when
first placed in service and again after the *Iu'hes have "aged" perhaps 12 hours.
Recheck every few months.

The belt and Mustache aec¢ion of the amplifier wins the renewing:

- An accurate dAraonval type meter calibrated. on the left

2.-

3--

1581 momma:

for both the Ac and. the DC balances and again on the right to
imitate the proper 120 Dillinger: BIAS condition.

Three screwdriver adjustments mined. AG BALANCE, DC BAIANCB
Ind BIAS. erped mind the meter, they ere protected.
um accidental shifting of calibration by black plastic
screw-on cape. These should be renamed before warming up
for test to avail] burning hands on hot tubes.

A heat switch having four pasitions marked: woman. (playinz
yosition), ms, D.c. mm am me. mm. m latter
three are the bent yositione corresponding to the meter readings
and adjustments listed in 1 a 2 above.

(Before nah these tests be sure to turn the vvlume control down
on the s1 sauree connect to lifie

1.-

3.-

Turn {Nat Switch he the BIAS test position. The mefier pointer
will swim; in the right. Turn the Bias mutant caremuy
with a screwdriver until the meter reading is an the BIAS-

120 m. mark. (This reading v1.1.1 normally vary slightly during
use with the line voltage and with wax-mp. In installation the
BIAS may have to be reset. A current setting in excess of

120 me. will tend to decrease tube lire.)

antenna to the next best position, marked 1M). BALANCE,

proceed as before, turning the D.C BALANCE Adduentnt until
the needle 1a centered over the W" or zero mark an
the left or the meter dial face.

The A.C. 1:ch nosition on the test switch has a wring
return an that if. will not accidentally be left in this
martian for any period of tin. 50mm; the knob to this
position a M eecends at a time turn the A.C. 3W
Adjustment so that the needle again is centered over the
Balance-Zero m1:- In this test the needle will be seen to
vibrate scum but it mu not be difficult to read. the
correct position-

:l'he Amplifier 13 now correctm manned and the teat switch
should be returned to the NORMAL or playing position. it
sure to replace the pratective plastic adjustment can

so that the amplifier will not be accidennm thrwn

out of calibration.

We Company, 25-11: Broadway, Long Island City 6, N. Y.