Audio Research REF75SE Technical manual

PROCEDURE NUMBER

REF75SE Update

ISSUED: 3/20/2015

Title:

REF75SE

Update Procedure

Caution Electrical Shock Hazard:

To prevent electrical shock make sure the AC POWER CORD IS NOT CONNECTED TO

THE REF75

DO NOT touch the Vacuum Tube Socket Pins when inserting or removing the vacuum

tubes, as there may be hazardous voltages present even after the REF75 has been

switched “Off” for a period of time.

If the REF75 has been “ON”, allow the Hot Vacuum Tubes to cool first before removing.

PROCEDURE FOR:

REF75SE Update

PAGE: 1 of 11

ISSUED: 3/20/2015

1.0 PURPOSE

The purpose of this document is to define the process for updating the REF75

Amplifier to a REF75SE Amplifier.

2.0 SCOPE

This document specifies materials, equipment, and assembly instruction and safety

precaution requirements for assembling the SE Update Kit.

3.0 EQUIPMENT

3.1. Hand Tools Required:

3.1.1 Diagonal cutters, Needle Nose Pliers, Nut Driver, and Phillips Screwdriver

3.2. Solder Tools Required

3.2.1. Small and Large Tips, High Power Solder Iron, Solder Remover or Solder Sucker

3.3. Kit Includes

Quantity

Description

Part

Number

Top Cover SE Badge

10132310

Rear SE Badge

10132410

Tube Damper

20004660

6-32 X 2.0" Hex Spacer

21406031

Hubbel Connector (IEC)

23201820

High Speed Diode

30506700

6H30P Tube

32002301

KT150 Tube

32002601

3.15A Fuse

34600302

1.0Ù 3W Resistor

43100006

19.5" 16 GA White Wire

N/A

19.5" 16 GA White Wire With Black Sleeve

N/A

19.5" 16 GA Clear Wire

N/A

PROCEDURE FOR:

REF75SE Update

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ISSUED: 3/20/2015

4.0. PROCEDURE

4.1. Panel and Input Wire Removal

4.1.1. Remove 18 –#6 Screws that secure the Top Cover to the Chassis.

4.1.2. Remove Top Cover.

4.1.3. Discharge the Power Supply!!

Refer to Figure 1 and 2 for the Discharge Points

Figure 1 Figure 2

4.1.4. Remove the 4 –KT120 and 2 –6H30P Tubes.

4.1.5. Use a large tip Solder Iron to remove 6 –Output Wires from the 2 –XLR Connectors.

Refer to Figure 3 for an example of an adequate Tip

Refer to Figure 4

PROCEDURE FOR:

REF75SE Update

PAGE: 3 of 11

ISSUED: 3/20/2015

Figure 3

Figure 4

Tip used for

resistor install

Tip used for

Component removal

PROCEDURE FOR:

REF75SE Update

PAGE: 4 of 11

ISSUED: 3/20/2015

4.2. IEC Update

4.2.1. Loosen the two terminal screws on the IEC that hold the Blue and Brown wires.

4.2.2. Remove 2 –Screws that secure the IEC to the Chassis.

Refer to Figure 5

4.2.3. Pull IEC out of the chassis far enough to gain access to the ground screw that holds

the GRN/YEL Wire and loosen the green screw to free the IEC.

Refer to Figure 6

4.2.4. Discard the old IEC and replace with the new IEC (23201820).

*Make sure the GRN/YEL, Brown, and Blue wire ends are tight!

*Loosen all the terminal screws on the new IEC to allow for easy insertion of the

Blue and Brown wires once mounted in the chassis.

4.2.5. Insert the GRN/YEL wire into the ground terminal and secure the terminal screw

tightly.

Refer to Figure 7

4.2.6. Insert the new IEC into the chassis and secure with the 2 –Screws removed in Step

4.2.2.

4.2.7. Place the Blue and Brown wires back into their respective terminals and tighten the

screws firmly.

Refer to Figure 8

*Use care when working around the fuse holder terminals as they can be broken

without the proper care!

PROCEDURE FOR:

REF75SE Update

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ISSUED: 3/20/2015

Figure 5 Figure 6

Figure 7 Figure 8

Figure 9

PROCEDURE FOR:

REF75SE Update

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ISSUED: 3/20/2015

4.2. Resistor Replacement

4.2.1. Remove 4 –1- 1.0Ù 2W Resistors (outlined in Figure 10) and replace with 4 - 1.0Ù

3W Resistors from the update kit.

*Reuse the containment sleeves from the removed resistors on the new ones.

*Make sure to heat the component and through hole enough so as not to pull the

through hole pads out with the components!

Figure 10

Figure 11

Figure 12 Figure 13

PROCEDURE FOR:

REF75SE Update

PAGE: 7 of 11

ISSUED: 3/20/2015

4.3. Diode Replacement

4.3.1. Remove the 4 –Diodes from the main board and replace with the 4 –High Speed

Diodes (30506700) from the update kit.

*When removing the old diodes, start by removing the lead closest to the capacitor

bank first, followed by the lead near the edge of the board; this will allow you to

access both leads with the solder iron!

4.3.2. Prepare the 4 –Diodes by forming the leads like the Diode shown on the right in

Figure 16.

Figure 14 Figure 15

Figure 16 Figure 17

*Arrow indicates the side the text faces!

PROCEDURE FOR:

REF75SE Update

PAGE: 8 of 11

ISSUED: 3/20/2015

4.4. Mainboard Hex Spacer Replacement

4.4.1. Place masking tape over 6 –Screws on the bottom of the chassis that secure the Hex

Spacers.

*The other 2 –Screws are partially under the feet, so they won’t fall out when

removing spacers!

4.4.2. Remove 1 –Screw/Lock Washer from the top of the mainboard and the 2-1/4” Hex

Spacer, then replace with a 2” Hex Spacer from the update kit one at a time until all 8

–Spacers are replaced.

*Note: When replacing Hex Spacer, do not tighten the screws fully until all Screws

are started in the Spacers, this will allow for proper alignment of the Screws and

prevent you from stripping the threads on the Hex Spacers!

Figure 18 Figure 19

“+”Indicates Hex Spacer Screw! *If one or more of the Hex Spacers doesn’t

line up, loosen the bottom screw, get the

screw started, and then retighten the

bottom screw!

PROCEDURE FOR:

REF75SE Update

PAGE: 9 of 11

ISSUED: 3/20/2015

4.5. Input Wires and Panel

*Make sure the following wires are through the through hole before soldering and

when soldering use extreme caution not to melt and damage the wire insulation!

Repeat Steps 4.5.1 –4.5.4 for each channel

4.5.1. Solder 1 –16 GA White Wire w/Sleeve from the update kit to the “+” location on the

main board.

4.5.2. Solder 1 –16 GA Clear Wire from the update kit to the Ground location on the main

board between the “+” and “-” locations.

4.5.3. Solder 1 –16 GA White Wire from the update kit to the “-” location on the main

board.

4.5.4. Twist the 3 –Wires in 1-1/2 Counter Clockwise Rotations (when standing at the

front of the unit) and then place in the respective locations in the XLR Connectors

and solder.

Refer to Figure 21 to make sure the wires are in the correct orientation!

Figure 20 Figure 21

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