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901 SPEAKER PART LIST
Item Num ber 1 2 3 Description Driver, 4.5" G asket, Driver, 4.5" G rille, Front, Dark Brown G rille, Front, Black G rille, Front, Sand G rille, Rear, Dark Brown G ille, Rear, Black G rille, Rear, Sand Logo, Brown/G old Logo, Black/Ivory Nut, Spring G asket, Rear G rille Nut, Knurled, 8-32 W asher, Flat, .174" Trim Ring, Term inal, 4" Carton, RSC Packing, End Cap Sheet, Dec O f Conform ity Screw, Tapp, 8-11 x .625, Pan Bag, Poly, 23 x 44 x 10.5 x 1.25 Foam Tape Part Num ber 124276-5 128407 136888-5 136888-3 136888-1 131436-5 131436-3 131436-1 138507 138508 125756 132323 100424-1 121646 118254 181768 131447 184056 172672-10 100652 118223 Q ty 9 9 1

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1

5 6 7 8 9 10 11 12 13 14 -

1 1 2 2 4 1 1 2 1 27 1 12

Figure 5. 901 Speaker Exploded and Packaging View
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901 EQ DISASSEMBLY/ASSEMBLY PROCEDURES
Note: Numbers in parenthesis correspond to item call outs in Figure 9. 1. Top Cover Removal 1.1 Remove the four screws (17) that secure the top cover (12) to the chassis (11) 1.2 Lift the top cover off. 2. Top Cover Replacement 2.1 Place the top cover (12) onto the chassis (11) and secure it with four screws (17). 3. PCB Removal 3.1 Perform procedure 1 first. 3.2 Remove the six screws (20) (21) that secure the PCB to the chassis (11). 3.3 Lift the PCB up. The front and rear panel will lift up with the PCB. 4. PCB Replacement 4.1 Line up the screw holes in the PCB with the standoffs on the chassis (11). 4.2 Replace the six screws (20) (21) that secure the PCB to the chassis. 5. Front Panel Removal 5.1 Perform procedure 1 and 3 first. 5.2 Pull the slide pot knobs (7) off. The front panel (13) will slide off. 6. Front Panel Replacement 6.1 Slide the front panel (13) on so that the slide pots protrude through the front. Replace the slide pot knobs (7) by pushing them on. 7.2 Remove the four screws (19) that secure the rear panel (14) to the RCA jacks. 7.3 Use a strain relief tool to remove the strain relief (10) that secures the line cord (15) to the rear panel. 8. Rear Panel Replacement 8.1 Replace the four screws (19) that secure the rear panel (14) to the RCA jacks. 8.2 Use a strain relief tool to replace the strain relief (10) that secures the line cord (15) to the rear panel. 7. Rear Panel Removal 7.1 Perform procedure 1 and 3 first.

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901 EQUALIZER TEST PROCEDURES
1. DC Measurement Test 1.1 Measure the DC voltages at the points listed in the following table. Refer to the schematic diagram for the test locations. Test Point TP1 TP2 TP3 TP4 2. Gain Test 2.1 Apply a 500mVrms, 100Hz signal to the left or right input. Adjust both slide pots to their center position and the bass switch to position 1. Reference a dB meter to the applied signal. 2.2 Measure the output according to the following table.
Input Left/Right Output Left /Right Monitor Position Source Gain -0.9 +1.0dB 0 +0.5dB -0.9 +1.2dB No Output Left (Right) Tape Inputs Left (Right) Tape Inputs

4. Distortion Test Note: Adjust both slide pots to the maximum cut position. 4.1 Apply a 2.0Vrms, 35Hz signal to the left and right input. 4.2 Measure the distortion at the left and right output. It should be 0.5%. 4.3 Apply a 1.0Vrms, 1kHz signal to the left and right input. 4.4 Measure the distortion at the left and right input. It should be .09%. 5. Separation Test 5.1 Apply a 600mVrms, 13kHz signal to the right input. Short the left input. 5.2 Measure the left output. It should be 18mVrms. 5.3 Apply a 600mVrms, 13kHz signal to the left input. Short the right input. 5.4 Measure the right output. It should be 18mVrms. 6. Noise Test 6.1 Short the left and right input. Adjust both slide pots to the maximum cut position. Place the monitor switch in the normal position. 6.2 The noise measured at the left and right output should be 30uVrms ANSI Aweighting.

Min. DC 22.5 14.25 -25.5 -15.75

Nominal DC 24.0 15.0 -24.0 -15.0

Max. DC 25.5 15.75 -22.5 -14.25

Left/Right Left/Right Tape Left/Right Left Tape /Right

Source Tape

3. Frequency Response Test 3.1 Apply a 500mVrms, 100Hz signal to the left and right input. Reference a dB meter to the left or right output. 3.2 Measure the left and right output according to the following table.
Freq. Bass 1 (dB) 9.8 1.5 Reference -5.8 1.0 -7.7 1.0 +.2 1.5 +.5 1.5 +12.2 1.5 Bass 2 (dB) 2.8 2.0 Both Pots Both Pots Max. Cut Max. (dB) Boost (dB) -12.5 2.0 -10.5 2.0 -3.4 2.0 +2.8 2.0 +0.5 2.0 -5.1 2.0 +4.3 2.0 +20.8 2.0

35Hz 100Hz 225Hz 650Hz 1.85kHz 3kHz 13kHz

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PART LIST NOTES
1. This part is not normally available from Customer Service. Approval from the Field Service Manager is required before ordering.

2. This part is critical for safety purposes. Failure to use a substitute replacement with the same safety characteristics as the recommended replacement part might create shock, fire and or other hazards.

VOLTAGE CONVERSION
Note: See Figures 6, 7 and 8 for the following procedures. The convertible transformer's part number is 120993.
120993

1. 220V to 120V Conversion Only 1.1 Remove LK-1 which is located in front of the transformer. 1.2 Insert two jumpers in the unmarked holes in front of LK-1. These jumpers should run parallel to each other. 1.3 Remove the 220V label that is located above the line cord. A label indicating the unit is 120V is located under the 220V label. 2. 120V to 220V Conversion Only
LK 1

LK 1

C1

P2

Figure 6. 220V Transformer 120993

120993

2.1 Remove the 120V transformer and replace it with the convertible transformer part number 120993. 2.2 Insert a jumper at the location marked LK-1 which is located in front of the transformer. 2.3 Replace C1 with the 220V value, part number 146354. 2.4 Place a label above the line cord indicating the unit is for 220V operation.

C1

P2

Figure 7. 120V Transformer 120993

120992

LK-1

Caution!
The location of LK-1 on early revisions of the 901 VI PCB were incorrectly marked. Refer to the following figures for the proper location of LK-1.

C1

P2

Figure 8. 120V Transformer 120992

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901 EQUALIZER ASSEMBLY PART LIST
(See Figure 9)
Item Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Description END CAP, 901 BUMPER, RUBBER BRACKET, MOUNTING, LED SLEEVING, CUT, CLEAR PVC SLEEVING 0.308" KNOB, SWITCH KNOB, POT SLEEVE, SWITCH KNOB FASTENER, TWIN FLAT, 8-32 STRAIN RELIEF CHASSIS, 901 VI EQ CABINET, EXTRUDED, CSI-1 PANEL, FRONT, BLK/GOLD 901-VI PANEL, REAR, 901 LINE CORD, 120V, POLARIZED, USA LINE CORD, 220V, EURO LINE CORD, 100V, NON-POLAR, JAPAN NUT, HEX, 4-40 STEEL SCREW, MACH, 8-32x2.37, PAN, XREC SCREW, MACH, 8-32x3/8, RNDW, XREC SCREW, MACH, 4-40x3/8, PAN, XREC SCREW, MACH, 4-40x3/8, PAN, XREC SCREW, MACH, 4-40x1/4, PAN, XREC CLIP, SPRING 1.31" Part Number 120988-10 103593 120975 134326-080 120987 120989 120990 120996 120997 106346 131507 131508 131509-0 136157-0 142801 113608 111672 103237-440 121316-38 121317-06 121319-06 121345-06 103140-04 121314 Qty 2 4 1 1 4 2 2 1 4 1 1 1 1 1 1

16 17 18 19 20 21 -

4 4 4 4 2 4 4

Figure 9. 901 Equalizer Assembly View
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