Harbach Electronics PM-200 User Manual

PM-200 POWER SUPPLY MODULE INSTALLATION INSTRUCTIONS

PARTS S UPPLIED WIT H THIS KIT:

(1) PM-200 Power Su pply Mod ule Circuit Board
(1) 15KΩ ½W 1% Resistor

To start the installation, read these instructions very carefully. Unplug the amplifier and
remove any input, output and control cables that may be connected to the back of the amplifier.
Remove the chassis from the case and remove the perforated sheet metal RF shield from the top
of the chassis. Remove the tubes and place them in a safe place. You are now ready to proceed
with the installation.

( ) Place the amplifier on its side (transformer down). Unsolder all wires connected to the

power supply circuit board. These are the RED and RED & YELLOW trans form er wires on

the top side of the circuit board, a GRAY wire and a YELLOW wire from the top side of the

board (these wires pass through the hole in the circuit board), the (3) 4.7MΩ resistor

assembly on the bot tom of th e circ uit board an d the heav y BLUE HV wire on the bottom

side of the board.

( ) Remove the fixed end of the (3) 4.7MΩ resistor assembly from the terminal strip lug and

discard these resistors.

( ) Remove the (9) 6-32 x 3/8” screws, was hers and nut s th at s ec ure t he c ircu it boa rd in place.

Save this hardware.

( ) Place the amplifier right side up and remove the 5 control knobs from their shafts.

( ) Remove the 3 nuts and washers that secure the bandswitch, meter switch and sensitivity

potentiometer and save them.

( ) Remove the (4) 6-32 x 3/8” Phillips-head screw s, washers and nuts that secure the front

panel. Save this hardware.

( ) Gently tilt the front panel forward. You may have to carefully pry it loose with a sm all

screwdriver because of paint stickage. Place the front panel down in front of the chassis.

( ) Lift the circu it board from the fro nt so that it tilts u pw ard about 1 ”.

( ) Using diagonal cutters, cut the old circuit board from the front left corner all the way back to

the wire hole. This will break out a path for the wires to exit. Be careful not to cut any wires

during this process. This will free the old circuit board so that is can be removed without

further unsoldering of wires.

( ) Carefully work the old circuit board out of the com partment and d iscard it.

( ) Take the n ew circuit board and work it into position with the wires passing through the slot

in the board.

( ) Secure the board on the right side with 2 or 3 of the 6-32 x 3/8” screws, washers and nuts.

Tighten enoug h to hold the board . They will be ad justed later.

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( ) Reinstall the YELLOW and GRAY wires in their marked holes in the circuit board and

solder.

( ) Swing the front panel back into position and reinstall the (4) 6-32 x 3/8” Phillips-head

screws, washers and nuts.

( ) Reinstall the 3 control flat washers and nuts and tighten.

( ) With the amplifier on its side (transformer down), install the remaining 6-32 x 3/8” screws,

washers and nuts holding the circuit board in place. Tighten all screws. You will have one

screw left ove r.

( ) Put the RED and RED & YELLOW transfo rmer w ires through their app ropriate holes in the

circuit board and s older.

( ) Place the amplifier upside down.

( ) Locate the 2-lug term inal strip just to the rear of the new circuit board. Remove the 15KΩ

resistor and clean the holes in the terminal strip lugs. Note: There is still a blue wire

connected to the insulated terminal lug.

( ) Connect the sm all BLUE wire connected to hole A on the circuit board to the insulated lug

of the term inal strip. DO NOT solder yet.

( ) Connect the supplied 15KΩ ½W 1% resistor between the 2 lugs of the terminal strip.

Solder all connectio ns (See pic torial).

( ) So lder the heavy BLUE HV wire to the circle pad marked “H” on the circuit board.

( ) Carefully inspect all work. Replace the front panel knobs (make sure they are prop erly

aligned with the fro nt pa nel markings).

( ) If you are also installing the SS-200 “Soft Start” module, you can proceed to those

instructions. If not, continue with these instructions.

( ) Reinstall the tubes and the perforated sheet metal RF shield on the top of the chassis and

put the chassis back into the case.

This completes the installation of the PM-20 0 pow er supply module. It will provide you with
a better power supply that provides the necessary B+ filtering and regulation. Your amplifier
should not experience any power supply problems in the future.

HARBACH ELECTRONICS

Jeff Weinberg – W8CQ

468 County Road 620

Polk, OH 44866-9711

[phone]

htt p://www.harbachelectronics.com

info@harbachelect roni cs. com

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