Fisher 125 A AX Service Manual

Page 1

SET 422

FOLDER 9

HEEIOTOFACTX Folcler

FISHER MODELS
125-A, I25-AX

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MODEL 125-Ax p

FISHER MODELS
125-A, 125-AX

TRADE NAME Fisher Models 125»A, 125 AX
MAN U FAC TUR ER
TYPE SET AC Operated Audio Amplifier

TUBES (Ten)

POWER SUPPLY

Types IZAU'I AF Amp. Phase lnv
Volt. Reg. Cont GYGGT Volt. Regulator, (2) SRAGY Rectifier

105425 Volts AC-50/ 60 Cycles

Fisher Radio Corp, 21-21 44th Drive, Long Island City 1, N. Y,

IZAX'T Driver (4) ELSé/ BCA'T Output, GAUB

RATING 1.92 Amp. @ 117 Volts (200 Watts)

ADJUSTMENTS

Connect a 16!; load to the output terminals.

Short the input jack.

Turn Level Adiust (R5) fully counterclockwise.

Remove the 3 caps covering these adjustments. Turn
each control to its mechanical center oi rotation,

Turn on the amplifier and adjust input voltage to 11'? Volts.
Hold Monitor Switchin Screen Volts" positions. Rotate
Screens (R2) until meter pointer coincides with screen
mark on meter.

7. With Monitor Switch in "Plate Current" position, rotate

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proper equipment is available.

ll Connect an accurately calibrated, low distortion audio
generator to the input receptacle.

2. Connectalefl lSUWresistor across the output terminals .

3i Connect either a harmonic or intermodulallondistortion
analyzer across the resistor.

4. Set Impedance Matching Switch (M7) to 169 position,

PERFORMANCE MONITOR ADJUSTMENTS (R2, R3. E4)

Plate Current (R3) until pointer coincides With plate
mark on meter.

. Hold Monitor Switch in Output Balance" position Rotate

Balance (R4) until pointer coincides with balance mark on
meter, or is within 1/ 8 inch.

. Check all three adjustments and repeat il' necessary.

Recheck alter 30 minutes.

. Hproperindications are not obtained, check output tubes

(V3, V4, V5, V6).

DRIVER BALANCE ADJUSTMENT (RE)

This adjustment is not necessary unless the associated circuit has been tampered with or repaired. and then only lithe

Turn ZvMauc Control (m) fully counterclockwise.

I Set the generator to 100% with an output slightly below

the clipping point 0! the amplifier output. Keep generator
output constant.

, Adjust Driver Balance (R6) tor minimum distortion on

the analyzer.

HOWARD W. SAMS & (20.,

The listing oi any available replacement part herein does
not constitute in any case a recommendation, warranty or
guaranty by Howard W. Sams Si Co. , lnc.. as to the quality
and suitability of such replacement part. The numbers oi
these parts have been compiled from information furnished
gsnoward w. Sal-us & Co., lnc., by the manufacturers 01

91

the particular type of replacement part listed.
ductlon or use without express permission, of editorial or
pictorial content in any manner is prohibited. No patent.
liability is assumed with respect to the use of the inlorma-
tioncontainedherein. @ l958 Howard w. Sams soc , lnc ,
Indianapolis 5 Indiana . Printed ln U. S. 0! America

DATE -58 SET 422

Indianapolis 5, Indiana
Repro-

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