Help with C500 SC45-20 Error (PS8 & 9)

[dagoof]

Was wondering if anyone could help - I bought a used C500 a couple of years back which I was unfortunately ripped off on (thread here. After initial problems with the corona wires and the waste toner sensor we'd managed to fire it up but weren't getting any colour. I'd managed to find a good tech locally and he reckoned changing the devs would help - and it did, we've got the colour back but the registration was way out. The tech thought it could be an easy manual adjust, but tried several times and the registration's not moving and it's still throwing up the 45 error.

He had tried cleaning the sensors (thought one of the shutters might be sticking) but that didn't help (said he tried swapping around PS8 & 9 but they were still showing the same error). So, he said it could be colour registration unit (pricey) but it could be worth trying to replace the sensors first (cheap).

Could anyone help us track down a part number on PS8 & 9?

[Mr Spock]

have him check the transfer belt. I have seen this stretch and walk to one side causing reg errors.

[Coptech]

I don't think I would change the sensors by themselves as there is a board on the unit and I am sure there is some calibration. The good news is that a board repair service such as Nationwide has the color registartion units advance exchange. I also think that the advice given on the transfer belt walk is the best start. The belts have rubber alignment bands on the inside edges and they will sometimes walk up onto the edge of the drive rollers.

[dagoof]

Thanks guys - he had mentioned the transfer belt can do that but didn't reckon that was the problem. I might be mistaken but I think there was something specifically indicating PS8 & 9 - he thought, replace the sensors (hopefully), failing that the registration unit (not the end of the world), but failing those two he reckoned it was the PCRB (AKA the end of the world).

Coptech - is Nationwide a US thing? I'm in UK unfortunately where the C500 and parts are pretty rare

[Stirton.M]

Replacing the registration assembly would be the first thing I would do if a failure in image registration could not be corrected via the control panel and the transfer belt unit looked in ok condition, no creasing of the edge due to walking, no obvious deformed surface...

If the problem is not resolved on replacing the sensor assembly, then the only other area referenced to this problem is to replace the PRCB, or have it repaired. There should be a repair service in the UK...contact your nearest Konica Minolta service support for information.

[Coptech]

Konica's electronincs are usually very sound. I think all board failures I have ever seen was a blown ICP caused by a shorted motor or technician error. (unplugging connectors under power or dropping a screw onto a powered board). Circuit Board Repair, Canon, Ricoh, Savin, Lanier Gestetner, Konica, Kyocera Mita - Nation-Wide Repair Service, Inc. (NWRS) I am sorry that I had not noticed the distance challenge. The only time I ever saw 45-20 was as mentioned, the belt walk. I removed the belt unit, took the tension springs off, walked it back into place and reversed the procedure to this point. There is also a dipswitch setting to disable the color registration which will let you get the machine powered up so you can run the adjustments to bring it back. Do a search of this site on 45-20. There was a recent thread that never ended but had all of the info needed I feel to fix the machine. Good Luck!

[seeb]

With the machine turned off, hold down the 2&5 keys and turn the power back on continue to hold 2&5 down until the machine comes up in 25 mode. Go to 1) Software switches set switch 25 bit 3 to a 1 this will turn off the automatic color registration. Power the machine off then back on and run copies and check for any missing colors. Correct any faulty colors, if ok start the machine up in 36 mode by holding down the 3&6 keys during power up, go to 2) Image adjustment 2) Timing adjustment 8) Auto color registration adjustment and hit the start key. If the adjustment is successful, go back into 25 mode and set switch 25 bit 3 to 0, turn off and back on and you should be good to go.

[Stirton.M]

Konica's electronincs are usually very sound. I think all board failures I have ever seen was a blown ICP caused by a shorted motor or technician error. (unplugging connectors under power or dropping a screw onto a powered board). Circuit Board Repair, Canon, Ricoh, Savin, Lanier Gestetner, Konica, Kyocera Mita - Nation-Wide Repair Service, Inc. (NWRS) I am sorry that I had not noticed the distance challenge. The only time I ever saw 45-20 was as mentioned, the belt walk. I removed the belt unit, took the tension springs off, walked it back into place and reversed the procedure to this point. There is also a dipswitch setting to disable the color registration which will let you get the machine powered up so you can run the adjustments to bring it back. Do a search of this site on 45-20. There was a recent thread that never ended but had all of the info needed I feel to fix the machine. Good Luck!

I've seen a few PRCBs fail on this series, and a few on the C6500 series too, specific to this issue. But yes, more often than not, the ICP was at fault...but in some situations, the IC itself was also damaged, in spite of the ICP being blown...chicken and egg kind of thing I think.

But that said, access to ICP suppliers is not really practical for end users...mostly because the suppliers sell these in bulk, usually lots of 1000 or so. Great if you are board repair dude...not so much for end users...assuming they were skilled at surface mount soldering...yet another hurdle...

[HORSE]

Are you 100% sure that the transfer belt is actually moving?

[Coptech]

assuming they were skilled at surface mount soldering...yet another hurdle...

OK, time to come clean. I usually bought replacement ICPs from an electronics supply house and left the old bad ICP in place and just piggybacked the new ICP to the old bad one. Sometimes it still left me solderng in a tight spot but as mentioned, I have no skills in surface mount soldering.

That being said, I really like the procedure that Seeb lated out for you.

[dagoof]

Thanks for the replies, I appreciate it. I should mention that last time we'd tried to fix this (almost a year ago) he'd had to replace the corona wires, and on starting up again this time round one of them had blown again. He said he'd be concerned if this happened again (that it could point to an HV problem) but luckily it didn't. Said it could just be down to the fact it's been sitting in a cold garage for 18 months.

Stirton - can you replace the sensor assembly separately, or just the whole registration unit?

Coptech & Seeb - thanks, I'll try both and see where it gets me.

Horse - it's giving the registration read-offs so I'm assuming so (and would've thought the tech would've been aware if that was an issue) but I don't actually know myself.

If it came to it I'd be prepared to find someone to do soldering if I could get an ICP. I'll be a broken man if it comes down to the PRCB - I convinced my dad we should buy this machine and it's cost several thousands already and so far it's scrap

[Stirton.M]

The registrations sensors come as an assembly.

65AA R758 00 is the part number to this.

Might I suggest that you get a certified tech to look at the machine. You will likely have better luck resolving this with someone who is trained on the unit and has some experience fixing them.

[dagoof]

Thanks Stirton - both techs have been certified AFAIK! If you see on my original thread, the first was from the company that originally supplied the machine (to the owner before me) but their tech didn't have a clue!

The guy we're using now was KM trained and knows the machine well, the only slight downside is that for the last couple of years he's been working for a company that do a range of brands.

[Stirton.M]

Oh...nuts!

Well, I guess the latter guy is the best route, though he may have limited resources. Not sure where you can go beyond this. If the belt is fine, no stretching or walking, is physically turning, the drive coupling on the belt to the drive motor is intact and not snapped off, cleaning unit is not preventing the belt from moving normally, registration sensor assembly has been checked, cleaned and or replaced. If all of that checks out as ok, the only item left is a possible issue with the PRCB, or some kind of problem with image reproduction, drum drive, laser issues...without a direct inspection with my own eyes, I cannot say with any certainty what else could be at fault. Charge units might be at fault...if the wire inside is broken and possibly arcing to the frame, though that is not very likely.

[dagoof]

Just a quick update - I've not had a spare minute to check anything else out (will be doing so tomorrow) but I spoke to my tech again and it's definitely not the transfer belt. He said it's turning ok, and he had tried the spare (used but working) belt I had - he'd also swapped the cleaning units around.

Funnily enough though, I was speaking to another ex-KM tech on here who said he'd seen this happen before when a machine had been moved (like mine) and the sensors had got really dirty. He said the sensors took a good couple of cleans with alcohol to get going again. Even though my tech had tried cleaning, I'm wondering if maybe they just need a bit more elbow grease. I'd like to try this and was hoping someone might have a guide to doing this? Have seen good, detailed, pictured how-to's on other threads.