Troubleshooting - Hilti DD 120 Mode D'emploi

Use an Allen key to tighten the carriage adjustment
screws to a torque of 5 Nm (finger-tight) and then turn
the screws back ¹/₄ of a turn.
The carriage is correctly adjusted if it remains in position
when no core bit is fitted but moves down under its own
weight when a core bit is fitted.
en

9 Troubleshooting

Fault
The machine doesn't start.
The service indicator lights.
The machine doesn't start and
the service indicator lights.
The machine doesn't start,
carbon brushes have been
changed, service indicator
lights.
The service indicator blinks.
The machine doesn't start,
drilling performance indicator
blinks red.
The machine doesn't start, theft
protection indicator blinks yel-
low.
The motor runs. The diamond
core bit doesn't rotate.
Drilling speed drops.
16
8.6 Checking the power tool after care and
After carrying out care and maintenance, check that all
protective and safety devices are fitted and that they
function faultlessly.
Possible cause
Interruption in the electric supply.
On/off switch defective.
Interruption in the electric supply.
The electronics are defective.
Water in the machine.
The carbon brushes are worn; the
machine will continue to run for a few
hours.
The carbon brushes are worn.
A fault has occurred in the power tool.
Motor speed error.
The machine has overheated.
The machine was overloaded for a
short time.
The power tool has not been un-
locked (tools with optional theft pro-
tection system).
Gear selector doesn't engage.
The gearing is defective.
The diamond core bit is polished.
The diamond core bit is polished.
Water pressure / flow rate too high.
maintenance
Remedy
Plug in another electric appliance and
check whether it works. Check the
plug connections, supply cords and
extension cords, GFCI and electric
supply.
If necessary, the power tool should be
repaired by Hilti Service.
Check the supply cord, extension
cord, supply cord plug, GFCI and
have them replaced by a qualified
electrician if necessary.
The machine should be repaired by
Hilti Service.
Dry the machine.
The machine should be repaired by
Hilti Service.
The carbon brushes should be
changed.
See section: 8.4 Replace the carbon
brushes. 10
Replace the carbon brushes.
See section: 8.4 Replace the carbon
brushes. 10
If necessary, the power tool should be
repaired by Hilti Service.
Have the machine repaired by Hilti
Service.
Wait 90 seconds until the light goes
out. Switch the machine off and on
again.
Switch the machine off and on again.
Use the TPS key to unlock the power
tool.
Move the gear selector until felt to
engage.
If necessary, the machine should be
repaired by Hilti Service.
Sharpen the diamond core bit on a
sharpening plate with water flowing.
The wrong type of core bit has been
used. Seek advice from Hilti.
Reduce the water flow rate by adjust-
ing the flow regulator.