Alpha 87A Blower Replacement Procedure

Unplug amplifier from mains power and remove top cover and power transformer.

1.0 Remove AC Module (AHX-X517)

l.l Unplug orange 3-pin connector at front of AC Module.

1.2 Remove #6-32 nut and washer at front of AC Module, and two #6-32x5/16 screwsand lock washers from back of chassis immediatelv above and below fuses. Pull ACModule clear of chassis center partition.

1.3 Remove two {16-32 screws and lock washers from front and left side edges of T/RModule cover, lift perforated cover off. Remove two *f4-40x1l2 screws and lock washersfrom back of chassis. Screws are located to right ofRF OUTPUT connector (viewedfrom rear of amp).

1.4 Remove two tl6-32x5/16 screws with lock washers on back of panel near 20Al250vfuse holders.

1.5 Unscrew #10-32x318 screw from inside T/R Module that mounts horizontal section ofplate choke to module.

1.6 Remove #10-32x3/8 screw from other end of horizontal section of plate choke.

1.7 Remove #10-32x3/8 screw from white Delrin post that connects solder lug to end oftank coil tubing. Remove tubes at this time.

1.8 Unplug 5 connectors from circuit board inside T/R Module. Remove two #6-32x318screws with lock washers and flat washers from left side of center chassis partition thatsecure T/R Module. Remove one lt6-32x3l8 screw with lock washer and flat washer fromback panel of chassis that secures coo( clamp. The T/R Module is now free of the chassisand can be lifted out of the way to remove blower assembly after step 3.3.

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2.0 Remove Tube deck

2.1 Remove four #6-32x5l16 screws with lock washers from top of tube deck. Removetwo #6-32x5l16 screws with lock washers from left 'lip' of tube deck.

2.2 Remove one #G32x5l16 screw with lock washer from front left-side of tube deck.

2.3 Remove one #6-32x5/16 screw with lock washer and flat washer from nylon cableclamp on front left-side of tube deck.

2.4 Remove two #6-32x5l16 screws with lock washers on back of panel near RELAY andRF INPUT connectors.

2.5Lift up on left side of 87A and stand it on right side of chassis. Remove four #6-32x5/16 screws with lock washers from bottom of tube deck. Remove tube deck bottomplate.

2.6Inside tube dech unsolder small white wire from feed through capacitor lead thatpasses through hole in INPUT MATCH board. This is in the upper-right corner ofthetube deck as viewed with amplifier standing on its right side.

2.7 Remove two #6-32x5/16 scrervs with lock washers and flat washers that are INSIDEthe tube declg near the lower edge of the INP{-ff MATCH board. A right-anglescrewdriver may be necessary.

2.8 Remove tfuee#6-32x5l16 screws with lock washers from inside oftube deck inside.These are along the edge of the tube deck on the same side as the previous two screws.Lift tube deck up and remove metal plate around blower housing.

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3.0 Remove Blower

3.1 Cut the orange 3-pin connector that was previous$ removed from AC Module (step1.1) from black blower wires. This will make removal of wires easier.

3.2 If blower shipping screws are installed, remove them (two #lo-32x318 screws withfiber washers) from back panel of chassis.

3.3 Remove six #6-32x5/16 screws with lock washers from bottom of chassis. This willloosen blower assembly and allow it to be lifted out of the amplifier.

3.4 Lower 87A chassis onto benctr, lift TiR Module out. Carefully lift the tube deck upout of its normal position, grasp the blower and remove it through the area where thetube deck was located. Do not scrape or nick windings of plate choke.

4.0 Replace Blower

4.1 Place new blower assembly in chassis, routing black wires the same way the originalblower wires were routed in amplifier. Do not nick or scrape windings of plate choke!

4.2 Follow steps 3.3 to l.l in reverse order, being careful not to pinch wires whenreplacing the T/R Module over the blower and tightening the mounting hardware.

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