User Guide

MM-220 OR PM-220 METER REPLACEMENT INSTRUCTIONS

PARTS SUPPLIED WITH THIS KIT:

(1) MM-220 or PM-220 Replacement Meter (Multi-Meter or Plate Meter)

(2) Panel Drilling Templates

To start the installation, read these instructions very carefully. Now unplug the amplifier

and remove any input, output and control cables that may be connected to the back of the

amplifier. Place the amplifier on a book, front panel up, and remove the bottom screws holding the

feet and case in place. Lift the case up and remove it from the amplifier. Place the amplifier on the

bench with the front panel facing you. You are now ready to proceed with the installation.

( ) Remove the 15 sheet metal screws that hold the perforated cover in place and remove this

along with the top rear plate cover.

( ) Remove the 3 large and 2 small knobs from the front panel.

( ) Remove the nut and washer holding the band switch to the front panel.

( ) Remove the nuts and washers holding the meter switch and sensitivity pot to the front

panel.

( ) Remove the 2 Phillips-head screws on the right side of the front panel.

( ) Remove the 2 Phillips-head screws on the left side of the front panel and loosen the front

panel. It may require a slight prying action with a screwdriver to separate the front panel

from the chassis due to paint stickage.

( ) Pull out the pilot lamp assemblies from each meter.

( ) On the back of each meter remove the nuts that secure the solder lugs to the meter.

( ) Remove the terminal strip attached to the front panel. The lower left nut on the plate

current meter fastens it. The front panel should now be free.

( ) Remove and save the mounting nuts for both meters and remove the meters from the

panel. The panel should now be free of all parts except for the Heathkit logo.

( ) Take a moment to clean the face of the front panel with hot water and dishwashing

detergent.

( ) Cut the supplied template sheet in half to separate the two templates. One of these is a

spare.

( ) Place one of the templates on the rear of the front panel and very carefully align the hole

patterns of the meter being replaced. The adjacent meter should be very close to also

being aligned (holding the panel up to a light source will aid in alignment).

( ) Hold the template in place with tape so that it will not move during the following operations.

Now check the alignment again.

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MM-220 OR PM-220 METER REPLACEMENT INSTRUCTIONS PART S SUPPLIED WITH T HIS KIT : (1) MM-220 or PM-220 Replacement Meter (Multi-Meter or Plate Meter) (2) Panel Drilling Templates To start the installation, read these instructions very carefully. Now unplug the amplifier and remove any input, output and control cables that m ay be connected to the back of the amplifier. Place the amplifier on a book, front panel up, and remove the b ot to m sc re w s holding the feet and case in place.
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() Carefully center punch the new upper right and lower left mounting holes. () Drill these holes w ith a 1/16” drill, keeping the drill perpendicular to the panel (a drill press helps, but is not necessary). () Drill out the upper right hole with a 1/8” drill. () If you have a 3/32” drill bit, use it to enlarge the lower left 1/16” hole, otherwise carefu lly enlarge this hole with the 1/8” dr ill. Th e drill will tend to drift into the larger (old) hole. The final size hole is to be 1/8”.
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() Reinstall the lamp assem bly into the meter not being replaced. () Bring the front panel up to the chassis. Put the tuning capacitor, loading capacitor and bandswitch shafts through their respective holes. Hold the front panel in place with the bandswitch m ounting washer and nut (loosely installed). () Replace the (4) 6-32 Phillips-head screws at each corner of the front panel. Secure with a lock washer and nut and tighten firmly.