MSSC qm7500 Technical Manual
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Table of Contents
QM7500 Technical Manual
Table of Contents . . . i
Introduction . . . 1
Maintenance . . . 2
Startup . . . 2
Shutdown . . . 2
Troubleshooting . . . 3
Servicing . . . 6
Preparing the QM7500 for Servicing . . . 6
Special Notes for Reassembling the QM7500 Printhead . . . 6
Standard QM7500 Assembly . . . 7
Printhead Assembly . . . 8
Controller Assembly . . . 9
Backflushing a Nozzle . . . 10
Backflushing a Valve . . . 11
Replacing the Nozzle Block . . . 11
Optional 7 mm, 15 mm, and 20 mm Nozzle Blocks . . . 12
Replacing a Valve . . . 12
Replacing the Regulator . . . 13
Replacing the Valve/Photocell Board . . . 15
Replacing the Display . . . 17
Replacing the Battery . . . 18
Replacing the Circuit Board . . . 19
Parts List . . . 20
Introduction . . . 20
QM7500 100/240V with US Power Cord . . . 21
QM7500 100/240V with International Power Cord . . . 21
QM7500 100/240V Arabic . . . 21
QM7500 100/240V Chinese . . . 21
QM7500 Printhead Assembly . . . 23
QM7500 Controller Assembly . . . 25
Consumables – Porous . . . 26
Other Components . . . 26
QM31930/03093 Rev AD Table of Contents i
QM7500 Technical Manual
Introduction This QM7500 Technical Manual provides you with complete maintenance,
troubleshooting and servicing information for the MSSC QM7500 Ink Jet Printer. It
also contains a replacement parts list.
CAUTION: This manual is designed for use by qualified technicians only. Any
unauthorized repairs will void your warranty. Unless you are a qualified
technician, do not attempt maintenance that is not discussed in the QM7500
Owners Manual (PN QM32004). You may accidentally damage components
resulting in injury or damage to the equipment.
For more information or assistance contact your local distributor or MSSC
Technical Support any time at (573) 437-7030; FAX: (573) 437-4030.\
QM31930/03093 Rev AD Introduction 1
QM7500 Technical Manual
Maintenance Startup
At beginning of each shift:
1) With the spray cap on the solvent bottle, spray the nozzles with solvent. In
harsh environments, you may need to spray the nozzles more often than once
per shift.
2) Purge the printhead.
3) Check the ink level in the bottle; install a new bottle if necessary. In harsh
environments, or if print quality declines, replace the ink bottle with solvent
and purge solvent through the unit.
Shutdown
If you are shutting down the unit for less than two weeks, simply turn off the
controller. You do not need to purge the printheads with ink or solvent. Also, do not
remove any ink that may have caked on the nozzle block. This will keep
contaminants from entering the nozzles. When you restart the unit, follow the daily
maintenance procedures on page 2.
If you are shutting down the unit for more than two weeks purge the printheads
with porous solvent. Leave the solvent in the ink lines until you restart the unit.
2 Maintenance QM31930/03093 Rev AD
QM7500 Technical Manual
Troubleshooting
Problem Possible Cause Solution
Row of keys fail to work. Chips loose on the circuit board. Make sure the RAM chip (U8) and
the software (U7) are properly
installed, and that the Zilog chip is
not loose.
Printed circuit board is defective. Replace the printed circuit board.
(See page 19.)
The green light is on, but the unit
will not print.
The unit prints intermittently. Wires disconnected from the
The print light is constantly
orange.
Wires loose from the barrel
terminals.
barrel terminals.
Printhead photocell board
defective.
Reseat any loose wires in the
barrel terminals. (See Figure A.)
Reseat any loose wires in the
barrel terminals. (See Figure A.)
Replace the printhead photocell
board. (See page 15.)
The machine resets itself. V alve shorted out. Replace the defective valve. (See
page 12.)
The unit will purge but not print. Wires loose from the barrel
terminals.
Reseat any loose wires in the
barrel terminals. (See Figure A.)
A dot or dots missing. Unit ran out of ink. Replace the ink bottle.
Nozzle clogged. 1.Spray the nozzle block with
solvent.
2.Backflush the nozzle. (See
page 10.)
3.Replace nozzle block. (See
page 11.)
Tube and jewel assembly in the
nozzle block cracked,
Replace the nozzle block. (See
page 11.)
QM31930/03093 Rev AD Troubleshooting 3
Worn valve. Increase dot size to temporarily
adjust for worn valve.
Valve became loose from the
valve board.
Reseat the valve on the valve
board.
V alve is defective. Replace the valve. (See page 12.)
Ink line became loose. Reattach the ink line.
Wires loose from the barrel
terminals.
Reseat the wires in the barrel
terminals. (See Figure A.)
QM7500 Technical Manual
Problem Possible Cause Solution
One or more valves fail to work,
resulting in missing dots
The unit comes on and the print
key is orange.
The dots are splattering on the
print sample.
Cable from the controller to the
printhead touched the valve board
causing a short.
Secure the cable from the
controller to the printhead with a
tie wrap.
V alve is defective. Replace the valve. (See page 12.)
V alve/photocell board is defective. Replace the valve/photocell
board. (See page 15.)
Unit locked up. 1.Unplug the power supply from
the unit, then plug it back in.
2.Zap the controller by keying in Z
A P Shift A.
CAUTION: Zapping the controller
will result in the loss of all print
parameter settings (dot size,
character width, print delay). These
will need to be reset after the ZAP
routine.
Note: Always perform the ZAP
routine after replacing softwar e.
Printhead too far away from the
product.
Position the printhead as close as
possible to the product without
rubbing against it and no further
than 3/8" (9.5 mm) away.
Note: Avoid contact between the
printhead and the product as this
may cause print quality to suffer.
No power. Unit is not properly plugged in. Plug unit into an appropriate
power source.
Ink is leaking from the regulator. Regulator is cracked or defective. Replace the regulator. (See
page 13.)
The bottle will not engage when
replacing the bottle.
Regulator is not properly seated in
the saddle of the printhead base.
Reseat the regulator in the
printhead base.
Regulator is cracked. Replace the regulator. (See
page 13.)
Display screen is blank or garbled. Display is defective. Replace the display. (See
page 17.)
4 Troubleshooting QM31930/03093 Rev AD
QM7500 Technical Manual
Problem Possible Cause Solution
Prints unrecognizable characters
when displayed correctly.
Message prints backwards or is
too long.
Power supply has recycled and
the QM7500 has defaulted to the
Hebrew language.
1.Type in th e correct language
code for the language you are
using. (If English is the
language being used type
ENGL.)
2.Zap the controller by keying in
ZAP Shift A.
CAUTION: Zapping the controller
will result in the loss of all print
parameter settings (dot size,
character width, print delay). These
will need to be reset after the ZAP
routine.
One of the two photocells are
dirty.
1.Clean the photocells.
2.Manually set the conveyor
direction, eliminating the need
for two photocells. See your
Owner’s Manual for instructions
on setting the conveyor
direction.
Photocell is defective. Replace the photocell boa rd. (See
page 15.)
Keyboard is not responding. Contacts on the PC board are
dirty.
Contacts on the back of the
keypad are dirty.
Figure A: Barrel Terminal Wiring Diagram
light brown
pink
brown
white
red
yellow
Clean the contacts.
Clean the contacts.
purple
gray
green
orange
blue
black
QM31930/03093 Rev AD Troubleshooting 5
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