37
Symptom
Possible Cause
Solution
Low power and/or low free
speed.
Insufficient air pressure.
Check air line pressure at the inlet of the Sander
while the tool is running at free speed. It must be
6.2 Bar (90 psig/620 kPa).
Clogged Muffler(s).
Model: OS 70x198mm
See the “Housing Disassembly” section for Muffler
removal. Replace Item 48, Muffler Insert (see the
“Housing Assembly” section).
Clogged Muffler(s).
Model: OS 75x100mm
See the “Housing Disassembly” section for Muffler
removal. Replace Item 46, Muffler Insert (see the
“Housing Assembly” section).
Clogged Muffler(s).
Model: OS 81x133mm
See the “Housing Disassembly” section for Muffler
removal. Replace Item 50, Muffler Insert (see the
“Housing Assembly” section).
Plugged Inlet Screen.
Clean the Inlet Screen with a clean, suitable
cleaning solution. If the Screen cannot be cleaned,
replace it.
One or more worn or broken Vanes.
Install a complete set of new Vanes (all vanes must
be replaced for proper operation). Coat all vanes
with quality pneumatic tool oil. See “Motor Disas-
sembly” and “Motor Assembly”.
Internal air leakage in the Motor Housing
indicated by higher than normal air con-
sumption and lower than normal speed.
Check for proper Motor alignment and Lock Ring
engagement. Check for damaged O-Ring in Lock
Ring groove. Remove Motor Assembly and Rein-
stall the Motor Assembly. See “Motor Disassembly”
and “Motor Assembly”.
Motor Parts Worn.
Overhaul Motor. Contact authorized Mirka Service
Center.
Worn or broken Spindle Bearings.
Replace the worn or broken Bearings. See “Shaft
Balancer and Spindle Disassembly” and “Spindle
Bearings, AirSHIELD™ and Shaft Balancer As-
sembly”.
Air leakage through the Speed
Control and/or Valve Stem.
Dirty, broken or bent Valve Spring, Valve
or Valve Seat.
Disassemble, inspect and replace worn or dam-
aged parts. See steps 2 and 3 in “Housing Disas-
sembly” and steps 2 and 3 in “Housing Assembly”.
Vibration/rough operation.
Incorrect Pad.
Only use Pad sizes and weights designed for the
machine.
Addition of interface pad or other material.
Only use abrasives and/or interfaces designed for
the machine. Do not attach anything to the Sander
Pad face that was not specifically designed to be
used with the Pad and Sander.
Improper lubrication or build-up of foreign
debris.
Disassemble the Sander and clean in a suitable
cleaning solution. Reassemble the Sander. (See
“Service Manual”.)
Worn or broken rear or front Motor
Bearing(s).
Replace the worn or broken Bearings. See “Motor
Disassembly” and “Motor Assembly”.
For central vacuum machines it is possible
to have too much vacuum while sanding
on a flat surface, causing the pad to stick
to the sanding surface.
For CV machines, reduce vacuum through the
vacuum system.
Troubleshooting Guide
DOC 0745
Rev 05/17/22
Summary of Contents for OS 343CV
Page 1: ...70 mm x 198 mm 3 x 8 75 mm x 100 mm 3 x 4 81 mm x 133 mm 3 x 5...
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