Troubleshooting Steps - Danfoss MCV104A Manual

TROUBLESHOOTING STEPS

1.
pressure when applying an electrical signal, actuate the
take the necessary safety precautions in the event full output
pressure is reached. If output pressure is reached with the
manual operator the problem may be electrical, in which
case skip to step 5.
2. If the manual operator fails to achieve full output in both
directions, ensure a minimum pump charge pressure.
within the PCP such as a lodged particle. Move to step 3
and check for the proper internal pressure reactions.
3. Checking the PCP internal pressures at neutral (null) and
with a full rated electrical command can help isolate a
problem. First shut
the two #6 SAE plugs in the sides of the PCP and place a
0-500 psi gage into each of these control ports. Once the
gages are in place start the system. The gage reading will
rise to approximately 40 ± 75 psi. If below 40 psi ensure
Readings should be within 10 psi or less of each other with
no command signal (i.e., 55 and 64 psi). If greater than 15
psi of each other replace the PCP. If the problem is a pump
creep in one direction and the gage readings are relatively
close to within 10 psi of each other, restoring the PCP null
is an option, proceed to step 4. Observe the gage readings
while stroking the valve manually, then stroke it electrically.
If either case fails to reach the proper minimum
pressure (psid) level replace the PCP.
© Danfoss, 2013
the hydraulic system then locate
erential
C1
control (EDC), pump or motor, do not adjust the pilot null. Adjust the
second stage valve null.
K07116 • Rev AB • September 2013
4. To restore the PCP null requires the hydraulic system to
be running and a gage in each control port. Locate and
remove the null access screw, a small amount of silicone
oil will likely escape from this opening which is acceptable.
Then insert a 3/32 allen wrench just beyond this opening
into the adjustment set screw and very slowly adjust CW
and/or CCW until gages are reading the same. Replace the
5. Checking for the proper electrical voltage or current requires
a Volt Ohm Meter (VOM). Check voltage set meter to the
Volt dc scale and place meter leads across the two wires
going to the PCP coil. Voltage requirements may vary from
one PCP model to another:
2.0 to 2.5 volts for single coil 14 to 85 mA models
2.0 to 3.0 volts for dual coil 22 to 130 mA models
4.0 to 15.0 volts for single coil 4 to 20 mA models
When checking current, place the VOM in series between the
electrical controller and the valve. Set the meter to the dc
amp scale and set the range to read mAs. The current level
should reach the minimum. If the proper internal pressures
are reached with the electrical signal (see Troubleshooting
Step 1), there is likely a problem with the second stage the
PCP is mounted to and it should be replaced.
Manual operator
Null adjust access screw-
remove screw, make null
adjustment with 3/32 inch
kex key, replace screw
CAUTION
C2
3002
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