"I have a HP LaserJet IIP, which does not print, but displays Error Code 52. Don, a man who is willing to help me fix mine, has a HP LaserJet series 2 that works. How similar are theses two machines? Is there any chance that one can swap parts to find the problem?"
(From: firstname.lastname@example.org and Michael Schuster (email@example.com).)
Totally different. Different cases, electronics, toner cartridge and system.
(From: Lewis King (firstname.lastname@example.org).)
Error code 52 is 'Scanner Malfunction' and there have been posts on the USENET newsgroup sci.electronics.repair that indicate that this is fairly common and is usually the cable leading to the scanner mechanism. These printers, and the CX before them, use insulation displacement connectors. Quite often the connection gets flaky and pressing down on the wires where they enter the connector will fix a problem (worked on my Xante Accel-a-writer when it was telling me I needed a new DC controller board).
The part you need is the scanner motor... I can't remember the part number, but it is the same as the scanner motor for a IIP+ and a IIIP. The scanner motor has three screws holding it in, in the box where the laser attaches to the side. As you pull off the scanner you will notice a square microprocessor on it's board. the bottom side of that board will probably have a dark spot where that processor got too hot. I fixed about 50 of them that way.
I will find out what the error code means and get back to you.
(From: Tony Duell (email@example.com).)
That sounds like the classic scanner motor failure on these printers. It's a very common fault, alas.
The 'Official' repair is to replace the scanner assembly (the entire unit - the black plastic box - on top of the printer), and if that fails to cure it, then change the DC controller board. But you can normally fix it a lot cheaper than that.
Here's how (I believe) the unit should work:
There's a frequency generator (FG) coil on the motor PCB, just like the one in a VCR. The signal is fed down the cable to J203 on the DC controller and then converted to a TTL signal by IC202A (LM393 comparator). It enters the gate array (IC206) and comes out again when it is fed to a TC9142 chip (IC203) which compares it to a reference clock also from the gate array. The error output from the PPL is conditioned by IC201b (LM358) and fed back to the scanner motor. There is feeds the control input of the TA7259 (IC401) chip which drives the motor windings.
First check that the cables are connected to J203 and J401 (inside the scanner unit). The most common fault is that IC401 has failed and probably burnt out R401 (8R2) with it. Fortunately, this chip is not custom - in the UK it's available from (e.g.) Grandata, so a VCR spares place might have one.
If you've still not got it working, get back to me, and I'll talk you through the test points on the PLL on the DC controller board. Hopefully the gate array is still good, since I've not found a source of those.
Oh yes, how to dismantle the scanner to replace the chip.
Firstly remove the outer casing from the printer. Then unplug the 2 cables on the scanner unit - one on J451 (on the laser PCB) and one on J401 (under the little flap on top). Undo the clamp screw in the back right corner, swing up the clamp and remove the beam detect fibre cable. Then remove the 4 screws and lift out the scanner unit.
Now, CAREFULLY cut back the melted-over studs and lift off the top cover. Keep dust to a minimum (obviously). Remove the circlip on the scanner motor spindle on the bottom of the unit. Remove the rotor and hexagonal mirror, taking care to note where all the washers go. Remove the small screws and lift out the PCB.
(From: Flemming (firstname.lastname@example.org).)
Where the scanner cannot maintain proper speed. Replace electrolytic capacitors on scanner board. All capacitors are 10 uF/16 V. Also replace the current measurement shunt resistor (R301) on scanner board. It has a value of about 1 Ohm. All these parts are in the black plastic box below processor.