Marantz 250 Addendum 1

Page 1

Addendum for Model 250

This manual is applicable to units bearing serial
numbers above 3500 and is the same as the manual
for units below that serial number except for the

following:

Throughout the original manual, replace A", "B",
"Channel A" and "Channel B" with "L", R, "L
Channel" and "R Channel", respectively.

Pagesz - Replace Figure 1. (Amplifier Simpli-

and 3

Page4 --

Page 4 -

Page 5 _

fied Schematic) with Figure 1. con-
tained herein.

Replace Figure 2. (Rectifier/Relay
Board Simplified Schematic) with Fig-
ure 2. contained herein.

Replace Figure 3. (250 Metering Cir-
cuit Simplified Diagram) with Fig-
ure 3. contained herein.

Replace 100, 220-VOLT AC CON-
VERSION with:

220-VOLT AC CONVERSION

To convert the Model 250 to 220-volt
operation, perform the following steps:

1. Remove the top cover.

2. Orient the Model 250 so that the
rear panel is facing toward the
viewer.

3. Locate TBI, the strip located on
the power transformer half shell
facing the rear panel, which ter-
minates the power transformer
primary wires.

4. Unsolder all jumpers from TBI.

5. Solder a jumper (18 AWG) to
TBl connecting the grey and
violet transformer wires.

6. Re-attach the top cover.

7. Replace the 6-amp, 250V fuse in
the unit with the 4-amp, 250V
fuse, Part #4514003, supplied
with the 220-volt conversion kit,
Part #105-1007-1.

8. Affix labels, supplied in conver-
sion kit, in the appropriate loca-
tions on the unit cover, and ad-
jacent to the line cord, fuse
holder and accessory outlets.

The Model 250 is n0w ready for 220-
volt operation.

Page 7 -

100-VO LT AC CONVE RSION

To convert the Model 250 to loo-volt
operation, follow the procedure out-
lined for 220-volt conversion except
for items 4, 5, 7 and 8. Item 7 is
eliminated. These items will read:

4. Unsolder the black and white
power lead-in wires and all
jumpers from TB1.

5. Solder two jumpers (18 AWG)
to TBI, one connecting the
orange and violet transformer
wires, and one connecting the
grey and white transformer wires.
Solder the black and white power
lead-in wires to the white and
orange transformer wires, re
spectively, at TBI.

8. Affix labels, supplied in the 100
volt conversion kit, Part #105-
1008-1, in the appropriate loca-
tions on the unit cover, and ad-
jacent to the line cord and ac-
cessory outlets.

The Model 250 is now ready for 100-
volt operation.

In Table l, for AC Power Control
Box, replace Fabricate in accord-
ance with Figure 3." with Fabricate
in accordance with Figure 4."; for
Amplifier Output Load Box, replace
Fabricate in accordance with Fig-
ure 4. with "Fabricate in accordance
with Figure 5..

In "PERFORMANCE VERIFICATION TEST
PROCEDURE," replace as indicated:

Page 8 -

Page 8 -

Page 8 -

Page 8 -

Page 9 -

In paragraph C. (DC Balance Test),
sub-paragraph 3 - Replace R504"
with "R502.

In paragraph D. (Total Hum and Noise
Test), sub«paragraph 2 - Replace
0.25 mv with 0.2 mv."

In paragraph E.(Bias Adjustment Test),
sub-paragraph 6 - Replace 10
watts with 7 watts."

In paragraph E.(Bias Adjustment Test),
sub-paragraph 7 ~ Replace R536
with R526" and replace 10 watts"
with "7 watts."

In paragraph F.(Maximum Power Out-
put), sub~paragraph 7 .. Replace
"analyzer with oscillator."

Page 2

Page 9 -

Page 9 -

Page 10 -

In paragraph G. (Relay Operation),
sub-paragraph 1 - Replace 2 min-
utes with 30 seconds.

In paragraph G. (Relay Operation),
sub-paragraph 3 - Add Drive both
channels.

Replace Figure 4. (AC Power Control
Box Simplified Schematic) with Fig-
ure 4. contained herein.

In "TROUBLE ANALYSIS, replace as indicated:

Page 11 -

Page 11 -

Page 11 -

Page 11 -

In SYMPTOM 1. - Replace "(100
watts or more)" with (80 watts or
more).

In SYMPTOM 1. PROCEDURE b. -
Replace "Check for open control
R224, 215-1005-1 bias assembly" with
"Check for open 215-1006-1 bias
assembly."

In SYMPTOM 5.- Add PROCEDURE
c. - Check C502 for leakage."

In SYMPTOM 7. - Replace PROCE-
DURE a. with Check for defective
C505, C506, C508, C509, C510, C516,
C519 and C520.

Page 12 -

Page 12 -

Pages 13 -
and 14

Page 15 -

Page 17 -

Pages 18 -
and 19

In SYMPTOM 9. - Replace PROCE-
DURE b. with "Check output for
proper clipping into 4 ohm load with
25.5 volts AC output (positive and
negative levels must not vary more
than 1 volt at 2 KHz).

Add SYMPTOM 11. - No Output
and add PROCEDURE a. Check
R529, 0510, 0511, 0802, 0803,
0804 and 0805.

PARTS LIST - The Parts List con-
tained herein identifies all parts which
differ from those used in units prior to
serial number 3501.

Replace Figure 7. (Power Amplifier
Board Component Assembly Diagram)
with Figure 7. contained herein.

Replace Figure 9. (Meter Board Com-
ponent Assembly Diagram) with Fig-
ure 9. contained herein.

Replace Figure 10. (Model 250 Sche-
matic) with Figure 10. contained
herein.