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|Printer and Photocopier Troubleshooting and Repair Collection : Guide to disassembly and reassembly of H..
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I used to fix lots and lots of HP II and HP III here in Brazil.
So, with time, I developed a "checklist" for HP II and III repairing,
that is safe enough to keep the printer working for years (4 years
and NO defects whatsoever) and customers were happy. I'll include things
not necessary for Americans (Brazil is HOT. Hotter than USA!) because
friends all over the world may need this info.
What you need: Isopropyl alcohol, toner sucker, good screwdrivers,
cotton, cotton swabs, screw picker (that little handy tool to
pick/put screws in tight places), some rags - and lots of space!
I'll take the HP III as an example, The HP II is equal, with very
minor differences. Please apologize me for any incorrections, since
I'm telling everything from memory.
- Be prepared to do a complete tear-down of the printer. Dismantle
it to the last screw. This is a day-long work, so better you are
prepared to do it. If you let for the following day, you WILL forget
where the assemblies go, and will make your job a trip to hell.
- Take the body cover entirely off. You will take total 6 screws,
one of them in the back of the printer. You take it off pivoting it
on your direction. It is a clumsy process, don't know why HP didn't made
- Take the front "shield" off. The "front shield" is a big sheet of
metal that covers the entire front of the printer. 5 or 6 screws, 2
ol the sides, 2 on the front, 1 or 2 on the top.
- Take the Power Supply off. You need to unscrew 2 screws on the
front of the printer, and one on the back of the power module,
besides the main motor. Also, disconnect the cable of the motor from
the power module.
- Look at the solenoids of the power module. It is very common to
have the solenoids' felts inside it became a messy glue. Take the
metal flap off (take care with the coil) and clean everything that
seems messy. Take 2 or 3 small squares of electrical tape, and put in
the nucleus of the solenoid. Do it on both, replace flap. Don't
forget the coil! Check the solder of the power module.
- Now is time to take the ozone filter support out. This is a black
plastic piece with 2 screws - one on the top, and another near the
motor. Clean everything with compressed air and a rag. Be sure the
filter is unobstructed. Better if you CHANGE the filter, but these
are impossible to be found in Brazil. So you clean it. Or you will
have some messy ex-gears. You have been warned.
- Take the fuser out - it has 4 screws on the corners. Take care of
it, there is a big and expensive lamp inside, and you don't want to
buy a new one, eh? We will not disassembly the fuser module if not
needed. But if you open the cover, pick the cleaning pad out and see
black lines on the fuser roller, it is time for a cleaning!!!
Dismantling the fuser is a complicated matter, but here we go: First
of all, study how every piece fits its place. You should begin the
dismantling by the right side, taking great care with the lamp. Take
off the plastic pieces at the sides of the fuser, take the lamp out,
so you are free to work. Store the lamp in a quiet place (no one
should even touch it he he he) and don'ts touch the glass with your
fingers - do it by the ceramic sides, or the wires. Clean the lamp
with cotton embedded in isopropyl alcohol and set aside. Take off the
locks of the gear on the right side of the fuser roller, there is an
equal lock on the left. Take off the fuser roller, and PLEASE don'ts
scratch it. You will see 2 thermistors on the fuser assembly, covered
with yellow plastic. Clean it with cotton swabs and alcohol. If they
are damaged (plastic is broken, missing a piece, has a hole, etc)
CHANGE IT. If the surface of these thermistors isn't smooth, it
WILL mark the surface of the fuser roller and WILL DAMAGE it. And
this is not a cheap part. Everything clean, assembly it again, doing
backwards what you did to unassembly. Remember this is a GOOD time to
change the fuser roller.
- Take off the AC module, where almost all the CX engine problems
are located :o) This is the aluminum "tower" besides the fuser
assembly, and where the AC cable comes in. Dismantle everything,
change the little little little heat accumulator (yep, it is so little
that should be called "heat accumulator") from the black TRIAC
besides the mains power connector, and put a good heatsink with heat
paste there. Also, clean THOROUGHLY the upper fan assembly, because
when it fails, it can make things hotter. Hot enough to melt the
fuser gears. :o) Remember: ERROR 50 = TRIAC open. A TIC 226 fits the
bill on place. Of course there are other causes for error 50. But
I've never seen that in Brazil.
- Time to go to paper path! Take the 4 screws that locks the
registration assembly in place. The registration assembly is the
module where you have the big green handle. Clean everything and note
if the "L" of the front is straight. If it doesn't make a 90 degrees
angle, fix it. Also, change the separation pad. It is the culprit of
99% of the pickup paper problems. What? You live in Brazil and cannot
buy new separation pads? So clean the black mess that was a long
time before a hard rubber, and put some kind of rubber or cork on it.
Also, take about 10 cm of isolating tape and cover the
lower half of the "separation pad" you did. The printer will not give
ONE pickup error for YEARS. BTW, I never had one return of this
method. When you put the registration assembly back, don'ts forget the
small yellowish piece on the front roller is assembled pointing the
frontal part of the printer!!! This is very important!
- Take the pickup roller out and clean it thoroughly. Use
turpentine to make it softer, it will last years! Of course, if
you have a replacement unit, better to use that.
- Using a cotton swab, alcohol and LOTS OF PATIENCE, clean the
corona wire. Be careful as you can, not to break the diagonal wires
that surround it.
- Do a GOOD cleanup on the inside of the printer. Use compressed
air (with a dehumidifier) and don'ts throw air in the scanner
assembly. Better never mess with that. Only open the scanner assembly
if you HAVE a problem with it. Hope you never have.
- Of course you already took the toner cart off, eh? Well, you
have a black metal plate, with instructions of putting a cart there.
Slide that plate to right, and move it up. You will see a very nice
and delicate frontal mirror. Use only cotton and alcohol to clean
that, and after only cotton to polish it. Make it clean, and close
the lid. Of course, you don'ts want to let it exposed. A nick on this
mirror, and there goes your print quality away.
- You have 2 contacts on the left part of the printer cover. They
touch the fuser assembly below. Do a continuity test there, you
should find some ohms, but continuity. If you don'ts find it, you have
a broken "erasing lamp" inside the printer cover. 2 screws keep you
far from them, better change it now
- Close the printer cover, turn the printer upside down, take out
the plastic pan on the bottom of it, take the metal pan, clean
everything including the lower fan. Of course, a lower fan broken,
is a laser printer broken. NEVER, I said NEVER run the printer with
the lower and upper fan disconnected, OK? Do you remember what I
said? You have been warned 2.0 :o)
Well, this completes my "HP Refurbishing method". To reassemble it, you
do the following:
- Bottom aluminum pan
- Bottom plastic pan
- Turn the printer up
- Registration assembly
- Pickup Roller
- AC Power module
- Ozone Filter Support (the black plastic thing)
- Fuser Assembly
- DC Module (don'ts forget the main motor cable!!!)
- Frontal shield
- Top cover (don'ts forget the cable for the front panel)
And so you have a healthy HP III. It will last for YEARS if you did
it right. don'ts forget to put a fresh new cart of toner and it will
last forever. Of course, you want to clean everything externally too.
The common disclaimers apply here. Do it at your own risk. I've fixed
some 500 HP LaserJet IIs and IIIs, and never had a problem, return or
anything doing that. Your mileage may vary. Greetings for Brazilian
friends, and for all around the world that uses that guide. :o)
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