HP CP4025 CP4525 - 59.F0 Error, diagnostics and repair - fast method

[blueytoo]

Service manual describes the supposed fix. But it is incorrect and following it could cost a lot of money. The described service manual steps would result in replacing sensor, fuser and ITB, none of which may be faulty and the machine would still generate the error message and then be deemed "unfixable".

As per the youtube videos on this error, in an old machine it is caused by a sticky solenoid and is fixable with no parts required. The videos show the major disassembly method required to removed the whole solenoid - includes removing 3/4 of the circuit boards and connectors.

Mine is CP4025 built 2011. I have fixed mine the long way. Now i believe it is fixable without major disassembly.

The core problem is age-related disintegration of polyurethane foam. Happens to both the solenoid damper and the ITB. ITB foam disintegration causes longitudinal print quality faults. The sticky solenoid is detected by the printer as transfer belt alienation failure.

My printer made a noise like slipping gears on powerup, which I believe is a gear spinning and the solenoid arm bouncing off it.

To verify the error, the diagnostics menu contains a number of tests. Manual drive motor tests verify that the motors for fuser drive, fuser pressure release and ITB are functional and do not generate the slipping gear noise. Manual sensor tests show bit state of sensors (0 off; 1 on) which can be flipped by manipulating the sensor. The ITB sensor flag sensor can be verified to be fully functional. (easier to play with with top cover removed.) Those tests make the troubleshooting steps and fixes in the service manual redundant. 

To access the solenoid requires removal of the top cover. Follow the instructions in the service manual. Note the upper left cover is the only cover with flexible tabs (top edge). All other parts release by flexing the whole part to release ramp catches or wide pins. Lever gently preferably with a wide blunt instrument. (I think a blunt table knife would cause less marking than screwdriver.)

The solenoid spring and lever are visible through a small access hole (approx 1/2 inch square) deep just to right next to the 4 straight wires (presume high voltage) in black plastic carrier. Study the solenoid. Coil is horizontal and lever vertical with right angle tab on bottom visible through the access hole.The lever is only attached by the spring, 2 long pins locate in notches on the arm. One pin is bent partly over, the other is straight. Once the spring is removed the arm comes off by lifting the side with straight pin.

Suitably bent wire can be used to push the solenoid arm, near the tab, towards the left hand end of the printer to verify the sticking problem with activation/deactivation.

To repair without further disassembly, a special tool (maybe bent wire or might need to be stronger) is required to hold the solenoid arm firmly and remove it after unhooking the spring. Extra long thin pliers or a locking surgical clamp might work. A spring hook or a small locking clamp are required. If the spring is dropped, major disassembly may be required to retrieve it. Access can be improved by moving the top wiring frame to the right - release the pin catch. (Pics in post below.)

I did this repair the hard way following a couple of youtube videos. To remove the solenoid requires major disassembly. Knowing more, it could be a very quick job, since the solenoid arm is accessible from the top access hole.

The gummy adhesive needs to be removed from the solenoid body and arm. (I used methylated spirits.) I used automotive wiring loom furry tape on the body and arm as a new noise damper. A cotton tip with wire down the hollow plastic centre could be bent and used to clean the adhesive off the solenoid body in situ.

(Disclaimer: i have not tested this minimal disassembly method since my printer is fixed, but photos illustrate access is feasible. Worst case scenario is the major disassembly method.)

I also replaced the disintegrated ITB foam with 3x3mm adhesive foam aircon duct foam tape cut down on guillotine. Still have some print quality issues and either need to replace ITB cleaning assembly (nongenuine) or the ITB.

My printer is less than 50% of ITB and fuser life, and the error is fixed.

[blueytoo]

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Why can't we post helpful pics?

[blueytoo]

Print quality has been restored to virtually as new. Just a few random specs I think come from the toner cartridge drums.

ITB wiping blade was contaminated with the gummy residue from the disintegrating polyurethane foam "wiper", and did not clean the ITB properly. The ITB cleaning assembly can be removed for cleaning.

Remove the ITB assembly from the machine and place on a suitable surface. Polyethylene foam sheet seems good. Bubblewrap is probably good too. Loosen the screw at each end of the black plastic part of the assembly. The two arms need to be gently separated so the front end can be fully unhooked from the ball bearing that locates it - needs about 5mm separation. The back end has a much longer greased pin, so unhook it second. Beware the front end of the cleaning assembly is where a number of small gears are and unclipping the whole part will result in the gears needing to be put back in place. (Doable but tricky.)

A. clean the ITB wiping blade with isopropyl alcohol until it is clean.

B. inspect and possibly replace the foam strip "wiper" (not sure if this functions as a mechanical wiper or just contains the air circulation around ITB cleaning)

Reassemble.

ITB belt can be cleaned with isopropyl alcohol on soft lint-free cloth. (Methylated spirits leaves water residue temporarily.) Putting the ITB assembly two thirds into the machine permits manual rotation of the white gear (UP is natural direction), inspection for surface contamination, and cleaning

[blueytoo]

solenoid arm and spring from toptypical design of wiring support frame pin catch and hooksmounting hole for solenoid after major disassembly - gear is locked by solenoid armgummy adhesive residuedisintegrated foamnew auto wiring loom tapesolenoid modelpin catch for wiring frame - top of machine

[blueytoo]

The long way - major disassembly. https://www.youtube.com/watch?v=J4wHU4dFQ0g 

Slightly shorter way - don't have to remove the DC controller PCA. https://www.youtube.com/watch?v=Bpwu8hRWBko

But do have to loosen enough cables and parts to move it enough to get access to the screws holding the" High-voltage power supply upper" (HVPS-T). I followed this guide but found I had to remove and loosen more to be comfortable to not cause damage. Require extra care to ensure the lower left corner (from rear) of the HVPS-T is on the outside of its mounting bracket when replacing.