Heathkit SB-10 Series Troubleshooting Manual page 22

6. 10uf @ 50v capacitor on the Modulator board (C2 on SB series)
7. 10uf @ 50v capacitor on the Bandpass board (C212 on SB series)
8. SB-102 only: two 500uf @ 25v (C941 and C942 located on LMO assembly)
Tighten all screws on printed the circuit boards. Replace any missing screws.
Lube controls (pots and switches) with DeOxit Fader Lube or other similar product. Rotate
controls through full travel several times to distribute lube.
Check tubes on tube checker. Replace any that are very weak or indicate shorts. If all
tubes are removed be sure to label their position for reinstallation in the same
positions.
While tubes and relays are out, clean each socket pin using a small dental brush
moistened with DeOxit D5 or other contact cleaner. If a tube seems loose in a
socket, or intermittent when wiggled, tighten the socket contacts by inserting a fine
sewing needle between the phenolic and contact so the contact exerts more
pressure on the tube pin.
Clean contact area on TX Mixer and Driver tube shields to insure good contact with
grounding tab on the socket. Failure to have good contact (or no shields installed) is
almost guaranteed to cause transmit instability issues.
Clean grounding clips on Driver shield (under chassis). Make sure clip screws are tight.
Clean or replace relays as required. To clean each relay, remove the cover and slip a
piece of index card moistened with contact cleaner between the contacts several
times. For the normally open contacts, it will be necessary to move the actuator to
the activated position to exert a slight pressure between the relay contacts and
moistened index card.
Lube shaft bushings with lightweight oil
Lube SSB/CW filter switch mechanism and ensure smooth operation.
Replace rubber belts on Preselector/Driver and Load controls
Check that the LMO has full travel (5 complete revolutions). Oil the follower pawls. If LMO
operation is stiff, clean grease from capacitor and reapply new grease (note: this
requires removal of the LMO).
Inspect and clean main dial using water only. If there are cracks in visible area, consider
replacing the dial with spare. If cracks in non-visible area, apply superglue to cracks
to prevent spreading (apply only on flat side of the dial, not on spiral side and not at
all on the numbered area!!). Clean spiral groove and apply Silicon Lube to groove.
Inspect spiral groove follower and repair or replace as required
Clean/polish the Preselector/Driver and Final Tune/Load control shafts, if needed. An easy
way to do this is to remove the shafts and chuck them in a drill while using fine
sandpaper to polish the shafts
General Inspection and Restoration Checklist revised 12/17/2021 Page 22