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 ADTable of Contents i
Page 4
Page 5
QM7500 Technical Manual
IntroductionThis 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 ADIntroduction 1
Page 6
QM7500 Technical Manual
MaintenanceStartup
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 MaintenanceQM31930/03093 Rev AD
Page 7
QM7500 Technical Manual
Troubleshooting
ProblemPossible CauseSolution
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 ADTroubleshooting 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.)
Page 8
QM7500 Technical Manual
ProblemPossible CauseSolution
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 TroubleshootingQM31930/03093 Rev AD
Page 9
QM7500 Technical Manual
ProblemPossible CauseSolution
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 ADTroubleshooting 5
Page 10
QM7500 Technical Manual
ServicingPreparing the QM7500 for Servicing
Before beginning work on the QM7500, follow these steps. Failure to follow these
steps may result in serious injury or damage to the unit.
To begin servicing the QM7500:
1) Remove the ink bottle.
2) Cover the front of the printhead with an absorbent cloth and purge the
printhead to remove any ink from the system.
3) Remove the QM7500 and power supply to a well-lit, static-free workbench.
Special Notes for Reassembling the QM7500 Printhead
Make sure the regulator is properly seated in the saddle of the printhead base to
allow proper connection of ink bottles. Also ensure that the valve retaining clip
offset is facing the valve board to prevent valves unseating from the valve board.
Finally, make sure that valves are properly oriented and seated in the valve board,
and that all wiring and tubing will not be kinked when the printhead cover is
replaced.
6 ServicingQM31930/03093 Rev AD
Page 11
Standard QM7500 Assembly
1
2
3
4
5
1. Controller
2. Frame
3. Power Supply
4. Bracket Assembly
5. Printhead
QM7500 Technical Manual
QM31930/03093 Rev ADServicing 7
Page 12
QM7500 Technical Manual
1
2
3
4
5
6
7
8
9
10
12
1. Valve Retaining Clip
2. Tubing (Nozzle)
3. Nozzle Block
4. Valve
5. Photocell Board
6. IDC Connector
7. Valve Board
8. Printhead Button
9. Regulator
10. Tubing (Valve)
11. Cable from Controller
12. Printhead Top
11
Printhead Assembly
8 ServicingQM31930/03093 Rev AD
Page 13
QM7500 Technical Manual
1. Gasket
2. Lens
3. Display
4. Tape
5. Controller Bottom Enclosure
6. Printed Circuit Board
7. Keypad
8. Controller Top Enclosure
1
2
3
4
5
6
7
8
Controller Assembly
QM31930/03093 Rev ADServicing 9
Page 14
QM7500 Technical Manual
Backflushing a Nozzle
1) Prepare the QM7500 for servicing. (See page 6.)
2) Remove the printhead cover by removing the three screws from the bottom of
3) From a print sample, locate the nozzle that needs backflushing.
4) Slide out the photocell board.
5) Disconnect the tubing connected between the valve and the nozzle from the
6) Place a cloth at the open end of the tubing.
7) Install the cleaner assembly nozzle (from the service kit) on a bottle of solvent.
the printhead. With the unit flat on the workbench, place your thumb on the
regulator and press down lightly as you lift up the top half of the printhead.
Note: Hold the components in place with your finger if necessary. Make
sure the valve/photocell board assembly remains in the printhead base.
Also, avoid unnecessary flexing of the cable between the two boards to
prevent damaging the cable connections.
valve end only; allow it to hang free.
CAUTION: Remaining ink pressure may cause ink to shoot out of the
tubing.
8) Press the solvent bottle against the clogged nozzle and spray solvent through it
for several seconds.
9) Reconnect the tubing to the valve.
10) Slide the photocell board back into place, photocells facing out.
11) Replace printhead cover, remount, and purge for several minutes.
10 ServicingQM31930/03093 Rev AD
Page 15
QM7500 Technical Manual
Backflushing a Valve
1) Prepare the QM7500 for servicing. (See page 6.)
2) Remove the printhead cover by removing the three screws from the bottom of
the printhead. With the unit flat on the workbench, place your thumb on the
regulator and press down lightly as you lift up the top half of the printhead.
Note: Hold the components in place with your finger if necessary. Make
sure the valve/photocell board assembly remains in the printhead base.
Also, avoid unnecessary flexing of the cable between the two boards to
prevent damaging the cable connections.
3) Slide out the photocell board.
4) Locate the valve that needs backflushing. (Valves requiring backflushing can
be identified by a print sample or by drooling or leaking ink.)
5) Disconnect the tubing between the regulator and the valve from the regulator.
CAUTION: Remaining ink pressure may cause ink to shoot out of the
tubing.
6) Remove the tubing between the valve and the nozzle from the valve.
7) Install the cleaner assembly nozzle (from the service kit) on a bottle of solvent.
8) Install tubing (from the service kit) on the cleaner assembly nozzle.
9) Connect the tubing from the cleaner assembly nozzle to the outlet (center) port
of the valve.
10) Place an absorbent cloth around the open end of the other tubing connected to
the valve.
11) Plug in the power supply and purge. (See the Owner's Manual for how to
purge.)
Note: If the QM7500 is not purging, you will not be able to run solvent
through the valve.
12) Spray solvent through the valve for several seconds.
13) Disconnect the solvent bottle from the valve port.
14) Reconnect the tubing from the inlet (off-center) port of the valve to the
regulator; reconnect the tubing from the nozzle to the outlet (center) port of
the valve.
15) Slide the photocell board back into place, photocells facing out.
16) Replace the printhead cover, remount, and purge for several minutes.
Replacing the Nozzle Block
QM31930/03093 Rev ADServicing 11
Removing the Nozzle Block
1) Prepare your QM7500 for servicing. (See page 6.)
2) Remove the printhead cover by removing the three screws from the bottom of
the printhead. With the unit flat on the workbench, place your thumb on the
regulator and press down lightly as you lift up the top half of the printhead.
Page 16
QM7500 Technical Manual
3) Carefully lift the controller mounting frame off the bottom half of the
4) Carefully slide up the photocell board.
5) Slide out the nozzle block.
Installing the New Nozzle Block
1) Pull off the ink tubes one at a time. As you disconnect an ink tube from the old
2) Slide the newly connected nozzle block into its slot in the printhead.
3) Replace the photocell board and printhead cover. Be careful not to pinch any
4) Install an ink bottle, plug the system in, and purge the QM7500 with ink to
Note: Hold the components in place with your finger if necessary. Make
sure the valve/photocell board assembly remains in the printhead base.
Also, avoid unnecessary flexing of the cable between the two boards to
prevent damaging the cable connections.
printhead.
nozzle block, connect it to the corresponding nozzle of the replacement nozzle
block. (See Figure B.)
of the wires in the printhead.
remove any air introduced into the system.
Your unit is ready to return to norm al operation.
Figure B: Valve Board to Nozzle Block Diagram
ValveValve
1
2
2
4
6
Optional 7 mm, 15 mm, and 20 mm Nozzle Blocks
An optional 7 mm, 15 mm and 20 mm nozzle block is available for the QM7500
printhead. If you wish to install a 7 mm, 15 mm or 20 mm nozzle block, see the
Parts List section of this manual for ordering information and follow the procedure
for replacing the nozzle block.
3
4
5
6
7
Nozzle
Block
Front View
1
3
5
7
12 ServicingQM31930/03093 Rev AD
Replacing a Valve
Removing the Valve
1) Prepare your QM7500 for servicing. (See page 6.)
Page 17
QM7500 Technical Manual
2) Remove the printhead cover by removing the three screws from the bottom of
the printhead. With the unit flat on the workbench, place your thumb on the
regulator and press down lightly as you lift up the top half of the printhead.
Note: Hold the components in place with your finger if necessary. Make
sure the valve/photocell board assembly remains in the printhead base.
Also, avoid unnecessary flexing of the cable between the two boards to
prevent damaging the cable connections.
3) Slide out the photocell board.
4) Locate the defective valve. (If a valve has shorted, it will usually be locked
open with ink leaking. A good valve has a resistance reading of approximately
16 ohms.)
5) Remove the valve retaining clip.
6) If necessary move aside functioning valves to get to the defective valve.
7) Disconnect both pieces of tubing from the valve.
CAUTION: Remaining ink pressure may cause ink to shoot out of the
tubing.
8) Disconnect the old valve from the valve board.
Installing the New Valve
1) Connect the tubing from the ink manifold to the intake (off-center) port on the
new valve.
2) Connect the tubing from the nozzle to the outlet (center) port on the new
valve.
3) Plug the new valve into the valve board.
4) Replace the valve retaining clip.
5) Slide the photocell board back into place, photocells facing out.
6) Replace the printhead cover, remount, and purge for several minutes.
Replacing the Regulator
Removing the Regulator
1) Prepare your QM7500 for servicing. (See page 6.)
2) Remove the printhead cover by removing the three screws from the bottom of
the printhead. With the unit flat on the workbench, place your thumb on the
regulator and press down lightly as you lift up the top half of the printhead.
Note: Hold the components in place with your finger if necessary. Make
sure the valve/photocell board assembly remains in the printhead base.
Avoid unnecessary flexing of the cable between the two boards to
prevent damaging the cable connections.
QM31930/03093 Rev ADServicing 13
3) Carefully lift the controller mounting frame off the bottom half of the
printhead.
4) Carefully pull the tubing off the regulator ports.
Page 18
QM7500 Technical Manual
5) Remove the regulator through the valve board.
Installing the New Regulator
Note: The new regulator has been factory adjusted. Any additional adjustment
will void your warranty and cause operating difficulties.
1) Position the new regulator through the opening in the valve board.
2) Using pliers, carefully slide the tubing onto the regulator ports, one at a time.
3) Replace the printhead cover. Be careful not to pinch any of the wires in the
4) Secure the printhead halves with the three screws.
5) Install an ink bottle, plug the system in, and purge the QM7500 with ink to
Your unit is ready to return to norm al operation.
Note: Over time the tubing end may stretch. You must trim the tubing to
ensure a snug fit on the new regulator ports.
printhead.
remove any air introduced into the system.
14 ServicingQM31930/03093 Rev AD
Page 19
QM7500 Technical Manual
Replacing the Valve/Photocell Board
Removing the Valve/Photocell Board
1) Prepare your QM7500 for servicing. (See page 6.)
2) Remove the printhead cover by removing the three screws from the bottom of
the printhead. With the unit flat on the workbench, place your thumb on the
regulator and press down lightly as you lift up the top half of the printhead.
Note: Hold the components in place with your finger if necessary. Make
sure the valve/photocell board assembly remains in the printhead base.
Also, avoid unnecessary flexing of the cable between the two boards to
prevent damaging the cable connections.
3) Carefully lift the controller mounting frame off the bottom half of the
printhead.
4) Carefully pull the tubing off the regulator ports.
Note: Over time the tubing end may stretch. You must trim the tubing to
ensure a snug fit on the new regulator ports or you may need to replace
the tubing.
5) Pull the tubing (all of it) through the opening in the valve board.
6) Disconnect the IDC connector from the valve board.
7) Remove the regulator.
8) Slide out the nozzle block; leave the valves connected to the nozzle block.
9) Slide out the valve/photocell board assembly.
10) Remove the valve retaining clip.
11) Disconnect the valves from the old valve board taking care not to bend or
break valve leads.
QM31930/03093 Rev ADServicing 15
Page 20
QM7500 Technical Manual
Front View
Installing the New Valve/Photocell Board
1) Plug the valves in on the new valve board. (See Figure C.)
2) Carefully slide in the new valve/photocell board assembly.
3) Slide the nozzle block into position.
4) Slide in the valve retaining clip and seat the valves.
5) Reposition the regulator.
6) Plug in the IDC connector.
7) Pull the tubing back through the opening in the valve board.
8) Reconnect the tubing to the regulator.
9) Replace the printhead cover, remount, and purge for several minutes.
Figure C: Valve Board to Nozzle Block Diagram
ValveValve
1
2
2
4
6
3
4
5
6
7
Nozzle
Block
1
3
5
7
16 ServicingQM31930/03093 Rev AD
Page 21
QM7500 Technical Manual
Replacing the Display
Removing the Display
1) Prepare your QM7500 for servicing. (See page 6.)
2) Remove the controller from the controller mounting frame.
3) Remove the three screws from the controller bottom to remove the controller
top.
4) Remove the tape that holds the display in place.
5) Disconnect the display from the connector on the printed circuit board.
Installing the New Display
1) Plug the new display connector into the printed circuit board.
2) Secure the display in place with tape.
3) Reconnect the halves of the controller.
4) Remount the controller to its mounting frame.
5) If necessary, adjust the intensity of the display screen by adjusting the
potentiometer on the back side of the circuit board.
QM31930/03093 Rev ADServicing 17
Page 22
QM7500 Technical Manual
Replacing the Battery
CAUTION: Danger of explosion if battery is incorrectly replaced. Replace only
with the same or equivalent type recommended by the manufacturer. Dispose
of used batteries according to the manufacturer’s instructions.
VORSICHT! Explosionsgefahr bei unsachgemäßem Austa usch der Batterie.
Ersatz nur durch denselben oder einen vom Hersteller empfohlenen
gleichwertigen Typ. Entsorgung gebrauchter Batterien nach An gaben des
Herstellers.
Removing the Battery
1) Prepare your QM7500 for servicing. (See page 6.)
2) Remove the controller from the controller mounting frame.
3) Remove the three screws from the controller bottom to remove the controller
4) Using a small screwdriver, carefully remove the battery.
Installing the New Battery
1) Install the new battery. Make sure to line up the mark on the battery with the
bottom.
notch on the chip.
2) Reinstall the bottom cover, and secure with three screws.
3) Reinstall the controller onto the mounting frame.
4) Reinstall the mounting frame on the conveyor bracketry.
5) Plug the power cable into the controller.
6) Plug in the power supply.
7) Reinstall the ink bottle.
18 ServicingQM31930/03093 Rev AD
Page 23
QM7500 Technical Manual
Replacing the Circuit Board
Removing the Circuit Board
1) Prepare your QM7500 for servicing. (See page 6.)
2) Remove the controller from the controller mounting frame.
3) Remove the three screws from the controller bottom to remove the controller
top.
Note: Avoid handling the new circuit board as much as pos s ibl e;
repeated handling could damage it.
4) Using pliers, carefully pull out the wires from the barrel terminals one at a
time.
5) Remove the old circuit board.
6) Remove the display from the old circuit board, disconnecting the connector.
7) Remove the PROM if necessary, by carefully prying it out. Be careful not to
bend the legs. Make note of the direction of the notch on the PROM. This
notch must match up to the notch on the socket on the new circuit board.
Installing the New Circuit Board
1) Insert the PROM into its connector on the new circuit board. Match up the
notch on the PROM with the notch on the socket to make sure the PROM is
pointing in the proper direction.
2) Replace the display in the new circuit board.
3) Place the new circuit board in the top half of the controller.
4) Reconnect the barrel terminals. Next to each barrel terminal on the circuit
board, is printed the color code of the wire that must be installed into that
specific terminal. (See Figure D.)
5) If necessary, adjust the intensity of the display screen by adjusting the
potentiometer on the back side of the circuit board.
Figure D: Barrel Terminal Wiring Diagram
light brown
brown
yellow
pink
white
red
purple
gray
green
orange
blue
black
QM31930/03093 Rev ADServicing 19
Page 24
QM7500 Technical Manual
Parts ListIntroduction
Use the Parts List to obtain whatever you might need to expand, upgrade, repair, or
maintain your system. The Parts List includes exploded illustrations of system
components with a textual parts listing.
To place an order, provide your local distributor or MSSC with part numbers and
quantities.
20 Parts ListQM31930/03093 Rev AD
Page 25
QM7500 Technical Manual
DescriptionPart Number
QM7500 100/240V with US Power Cord
QM7500 100/240V with International Power Cord
QM7500 100/240V Arabic
QM7500 100/240V Chinese
1. Power Supply, with US Power Cord
Power Supply, with International Power Cord