D-I-Y Repair Assistance Guide
HP 7100 Series Officejet Printers








Last Update: 5/09/2010
WELCOME!

Service Station Disassembly & Repair

OVERVIEW

Believe it or not, with a single torx wrench and 2 common items from your kitchen junk drawer, you can have your printer disassembled into easy-to-handle components in about 30 minutes, and complete access to your Service Station.

All-important to your printers operation, the service station is responsible for 3 primary functions:

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tools

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Tools Needed

Needed for disassembly are:
1. A cup or dish to hold screws or small parts
2. Painter's tape
3. A small flathead screwdriver
4. A #10 torx-head wrench
(you can get a torx-head wrench assortment similar to the one shown here at most hardware stores for under $5.00)

NOTE: Be sure not to confuse TORX with a HEX / ALLEN wrench. Hex or Allen wrenches / fittings have six flat sides; TORX wrenches / fittings are 6-pointed, and sometimes referred to as 'star' wrenches / fittings.



preparation

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7130 ready for disassembly

To begin we need to move the printer carriage to center (if your unit will do so). Turn your power on and raise the maintenance door, as if to change a cartridge. Once the carriage has moved to center, leave the maintenance door open while disconnecting the power.

Your printer should now be facing you, emptied of all paper and all cords removed. (Ink cartridges/print heads removed at your discretion)

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HP 7100 Disassembly Guide Image

Grasping the sides or center thumb recess, slide the paper tray out and set it aside.



removing the ADF

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HP 7100 Disassembly Guide Image

Raise the Auto Document Feeder to expose the scanning surface, and pull upwards on the black tabs to release the hinge locks. Slightly left of center between the hinge locks the wiring harness connection block is built into the hinge base. Initially you may need to use some gentle tilting/rocking motion to coax the wiring plug into releasing.

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HP 7100 Disassembly Guide Image

Notice the wire harness plug placement shown here. Once the harness plug is disconnected, the ADF will easily lift up and off of the printer base, and can then be set aside.



removing the Duplexer / Access panel

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HP 7100 Disassembly Guide Image

Reaching behind the unit, rotate the center knob to remove the center access panel, or if you have the 2-sided print unit (shown) depress the light grey button on each side and slide out for removal. Set aside.

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Scan Bed removal & Cabinet Disassembly

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HP 7100 Disassembly Guide Image

Lift the maintenance/cartridge access door to raise the scanner bed, as though you were replacing a cartridge. Reach just behind the left panel as shown and gently pull toward the center of the unit, then rotate outwards towards the front to remove the fascia.



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HP 7100 Disassembly Guide Image

Repeat this step for the right fascia panel.

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HP 7100 Disassembly Guide Image

Grasping the lifts just below the hinge point, fold them slightly inward (closed) and lift upwards to detach them from the base. (If this does not release them easily, use your small screwdriver to spread the latch points side to side). Once released, raise the scanner bed to a fully open position.

Caution: the base may now become unsteady as the weight is moved towards the back. Leaning the scanner bed against a wall behind the printer or having a second person to support it will help.



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HP 7100 Disassembly Guide Image

Use the #10 torx wrench to remove the 2 screws shown in the recess of the metal access panel. Lift the panel up at the recess, then slide / tilt it away to one side.

A ground wire is attached by a third screw on the panel. This can also be disconnected to get the panel completely out of the way, but is not necessary.

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HP 7100 Disassembly Guide Image

Below the access panel, you will find 3 wire bundles and an FFC (flat flexible cable), as seen here, each connected to a circuit board and passed through a dark grey/black piece, which is a ferrite shield which helps protect the cables from stray data signals. Unplug each from the circuit board, noting that the FFC has no "plug", but simply slips out of a channel. Be careful to not bend the FFC; keep it nice & flat.

Each plug is a different size, so no need to overly worry about which one went where; they cannot be mixed up. Once disconnected, you can remove the scanning bed w/the wire harnesses and access panel (still attached to the scanner by a small ground wire) by tilting back (open) and lifting straight up. Set the assembly aside.



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HP 7100 Disassembly Guide Image

Reaching in the through the printing bay, disconnect the large ribbon cable at the left, pulling upwards to unplug.

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HP 7100 Disassembly Guide Image

Next remove the 2 #10 torx screws circled in the photo.



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HP 7100 Disassembly Guide Image

Now tip the unit onto it's back for access to 4 of the 6 interlock tabs that will release the main shell from the deck. The two side latches are readily visible, but the two at the front are recessed. You can also see/feel the front catches from inside the case, but once located they are easiest to release from underneath using your screwdriver to unlock them.

Getting them all unlatched at once but not too far out of position can be a little tricky and works best by doing one side at a time (left w/left front, right w/right front). Just get them unlocked; don't try to remove the housing yet. Once they're loose, carefully stand the unit back upright, holding onto it by the metal base not the housing.

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HP 7100 Disassembly Guide Image

The remaining 2 latches are tucked in on each side of the rear access panel, and they release in reverse of the other latches (the open end of the tab is pointed up, not down). Note the location of my fingertips in the photos at left & below: feel for the latches and then slip your fingertip between the latch and the outer shell to press the latches inward and lift slightly to release the shell. Again, only dislodge the housing enough to prevent it's snapping back into place.



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HP 7100 Disassembly Guide Image

TIP: To prevent the cabinet snapping back down as you work, place a thin paperboard strip, such as a matchbook cover, between the upper and lower case sections at each point as you separate them.

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HP 7100 Disassembly Guide Image

To remove the main housing, lift carefully, keeping it level front-to-back, the right side (service station side) slightly ahead/higher than the left. Watch on the left from above, where the metal access panel was, as the fax/phone circuit board must slide closely from behind the main board as it rises.

You can alternately first remove the fax/phone module by removing the single screw and cover surrounding the phone jacks, then pulling straight outward on the board to disconnect and remove it.



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HP 7100 Disassembly Guide Image

For service station repair, the right-hand base trim must also be removed. Start by unlocking the front tab as shown here, while slightly tipping the front wrap upwards.

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HP 7100 Disassembly Guide Image

A similar action is used to unlatch the back tab, although I found it easier to reach from below.

Take notice of the location of the small notch opening where the screwdriver is in this photo.



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HP 7100 Disassembly Guide Image

Once the front and back tabs are loose, rotate the trim down and away to unhook two side tabs from the metal base.

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HP 7100 Disassembly Guide Image

On the rear right-hand corner, disconnect the harness shown here.

Also note the large, gauged black discs on the rear wall; these are alignment dials which should not be loosened or disturbed!



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HP 7100 Disassembly Guide Image

Now, facing the front, slide the printer carriage all the way to the left side. Look closely at how the encoder strip (the smoke-color plastic ribbon) attaches to a spring metal tab on the left and is hooked over an angled metal pin at the right, just above the service station tray. On the right, pinch the strip between your fingers and gently pull to the right and tilt, unhooking the strip from the pin.

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HP 7100 Disassembly Guide Image

Keeping the strip taught but not stretching or over-tensioned, use a small piece of tape to temporarily secure the loose end to the metal shield just behind. This simply helps to keep the encoder strip properly attached and threaded through the printer carriage while you continue.



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HP 7100 Disassembly Guide Image

Remove the single screw holding the encoder mast to the gantry (round rail), and lift the mast up to unhook it.

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HP 7100 Disassembly Guide Image

The service station is now completely free. Carefully slide it straight out the right side of the deck, paying attention to not get caught in the wiring at the back near the motor.



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HP 7100 Disassembly Guide Image

Looking at the underside of the service station, you can see the single screw attaching the motor strap and holding the motor in place. The 2 screws below do not need be undone unless you wish to clean transfer gearing. The red arrow is where you will disconnect the wire harness for ease of working to transfer the small circuit board to the new motor. The blue arrow notes the U-shape position sensor which works by reading the passage of the tabs/spaces that fringe the round disc on the end.

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HP 7100 Disassembly Guide Image

After disconnection of the wire harness and removal from the service station mounting, your original motor unit will include: a brass worm gear on shaft "A", and a small circuit board plus a black or clear plastic disc on shaft "B". Holding the worm gear in one hand to prevent the shaft spinning, use a gentle "unscrewing" motion to remove the plastic disc with the other hand. Next, remove the circuit board by carefully un-soldering from the two terminal points. (You may have to work each terminal a little at a time, "inching" the board upward until off of the terminals.)



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HP 7100 Disassembly Guide Image

In removing the brass worm gear, it is critical that you not damage the thread surfaces. My approach was thus: I located a scrap of plate metal just thin enough to fit between the motor body and the inner end of the worm gear. Using a hacksaw, I cut a slot in the metal scrap just wide enough for the shaft to slide through. Placing the unit in the mouth of a vise (without clamping the motor), find a nail or rod just smaller than the shaft and flatten the end, then with light taps of a hammer use as a driving pin to drive the motor shaft out of the worm gear. (a drop of light oil or WD-40 is of help, too)

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preparing the new motor

Step 1: Firmly, but carefully, clamp shaft "B" into the vise and tap the worm gear into place on shaft "A", taking care to seat it down the shaft the same distance out from the motor it was on the original. (I used my scrap metal plate as a guide).

You have two options at this point; to shorten or not to shorten shaft "B". To shorten the shaft, mark the shaft to be cut so that it matches the length of the original. Clamp the area that is to be cut off firmly in the vise, and use the edge of the vise as guide for your hacksaw. Smooth the cut end with fine sandpaper or a file to remove any burrs.

If you do not wish to shorten the shaft, the alternative is going to be using a drill bit the same size as the shaft to core the end of the black plastic disc, so that it can slide clear down a shaft instead of seating on the end. You will then secure the disc onto the shaft at the proper distance using a super-glue. There is ample room inside the printer housing for the extended length of the shaft, and it will not interfere with operation. If shortening the shaft, do so now before moving to the next step. If using the alternative, proceed to the next step now.

Step 2: Re-mounting the circuit board. The new motor will have 2 wire leads attached to the terminals which will need to be un-soldered and removed. In doing so, find any existing mark or use a felt-tip pen on the side of the motor to create a mark noting which terminal has the white lead wire.

Now, temporarily plug your wire harness back onto the circuit board. Notice the harness is all green wires, with only one white wire, which is on the left of the plug when viewing the board from the outer face. Trace the printed path on the circuit board leading from the white wire connection on the plug; as I recall, it will lead to the terminal connection that will be towards the left, passing by the black sensor block. You want to be soldering the circuit board onto the new motor so that the path from the white wire of the plug connects to the terminal on the motor which had the white lead wire attached. When you are sure of the correct polarity, solder the board onto the new motor, again "inching" down the terminals if needed, until seated evenly near the base of the motor. Do not remove any clear plastic disc from the motor before soldering! This acts to prevent contacts on the board from shorting against the motor housing!(Pins from the sensor and plug are soldered through the board, so the board will not necessarily seat in tight contact with the motor housing.

Step 3: If you cut off shaft "B", you can now re-attach the black disc onto the end of the new shaft. When it is fully seated, the tabs on the outer edge of the disc should pass freely through the center of the sensor block, but without touching it. (See diagram below)



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HP 7100 Disassembly Guide Image

If you opted not to cut off the shaft, find a drill bit that fits into the center of the plastic disc without binding. (i.e. preferably slightly smaller in size than the motor shaft) Use the bit to drill on through the outer face of the disc. Now you should be able to slide the disc onto the shaft, and past the tip, where the extra length of the shaft protrudes beyond the outer face of the disc. Ideally the disc still has some resistance against the shaft, not spinning freely, but allowing the shaft to pass on through the face. Once you have made sure the disc can be slid down the shaft into the proper place, clean the shaft and the center core of the disc with alcohol to remove any oils or grease. Lightly sand the surface of the shaft using emery paper if you have such, then press the disc down the shaft and position it into the proper location. If the disc easily slips / spins on the shaft, add a drop of super-glue around the disc center to ensure its location. Allow a few minutes for the glue to dry, then gently test for adhesion. (As there will never be any contact or force against the disc, it only need be secure enough that it won't spin out of place.)

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Your replacement motor assembly is now complete, and you are ready to start putting the printer back together. Before re-attaching the motor to the service station, take this opportunity to clean the station of all the past ink build-up. When you put the motor back into place, use the edge of the black disc to rotate the station through some of it's positioning, making sure everything is moves freely. You do not need to pre-set the station to any particular starting position; the only provision is to not have it beginning where the head seals (blue rubber squares) are in the fully up and "sealed" position. Leave the printer carriage out in the working area, not returned to the station. When you power up for the first time, the printer will take care of the initial re-aligning all on it's own.



The rest is easy; just follow the instructions in reverse, taking care to make sure pieces align easily without force, and that wiring, etc. is always free of binding.

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