Symptom
Low Power and/or Low Free
Speed
Air leakage through the Speed
Control and/or Valve Stem.
Vibration/Rough Operation
Note: All Sections referred to under "Solution" are located at the end of the manual in "Service Instructions"
Troubleshooting Guide
Possible Cause
Insufficient Air Pressure
Clogged Muffler(s)
Plugged Inlet Screen
One or more Worn or Broken Vanes
Internal air leakage in the Motor Housing
indicated by higher than normal air con-
sumption and lower than normal speed.
Motor Parts Worn
Worn or broken Spindle Bearings
Dirty, broken or bent Valve Spring, Valve
or Valve Seat.
Incorrect Pad
Addition of interface pad or other material
Improper lubrication or buildup of foreign
debris.
Worn or broken Rear or Front Motor
Bearing(s)
For 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.
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).
See the "Housing Disassembly" section for Muffler
removal. The Item 38 Muffler can be back flushed
with a clean, suitable cleaning solution until all con-
taminates and obstructions have been removed.
If the Muffler can not be properly cleaned then
replace it. Replace Item 39, Muffler Insert (See the
"Housing Assembly" Section).
Clean the Inlet Screen with a clean, suitable
cleaning solution. If Screen does not come clean
replace it.
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".
Check for proper Motor alignment and Lock Ring
engagement. Check for damaged O-Ring in Lock
Ring groove. Remove Motor Assembly and Re-In-
stall the Motor Assembly. See "Motor Disassembly"
and "Motor Assembly".
Overhaul Motor. Contact authorized Mirka Service
Center.
Replace the worn or broken Bearings. See "Shaft
Balancer and Spindle Disassembly" and "Spindle
Bearings, AirSHIELD™ and Shaft Balancer As-
sembly".
Disassemble, inspect and replace wore or dam-
aged parts. See Steps 2 and 3 in "Housing Disas-
sembly" and Steps 2 and 3 in "Housing Assembly".
Only use Pad Sizes and Weights designed for the
machine.
Only use abrasive and/or interface designed for the
machine. Do not attach anything to the Sanders
Pad face that was not specifically designed to be
used with the Pad and Sander.
Disassemble the Sander and clean in a suitable
cleaning solution. Assemble the Sander. (See
"Service Manual")
Replace the worn or broken Bearings. See "Motor
Disassembly" and "Motor Assembly".
For SGV machines add extra washer(s) to the pad
spindle to increase the gap between the pad and
shroud. For CV machines reduce vacuum through
the vacuum system and/or add extra washer(s)
to the pad.
7
Solution