Bizhub 421 with recurrent C-3902 Errors

[PeterG]

We have a customer that has persistent 3902 errors during winter. Almost always they are on a Monday morning, before the room has warmed up. It gets cold here, but not that cold compared to other countries. Once the machine has warmed up all is fine until the room heating is turned off and the machine goes to sleep.
So far the thermistors have been replaced twice, firmware updated and the entire fuser has also been replaced. Konica are suggesting the Print Control Board or the power supply.

My problem is that I may replace these boards & not know whether is has fixed the problem until next winter.
Any Input would be greatly appreciated.

[Shadow]

Re: Bizhub 421 with recurrent C-3902 Errors

did you replace thermistor 2 and reform it to make contact with the heat roller?
have you replaced the upper fuser roller with an inferior part?
have you removed the lamp and inadvertently rolled it so the nipple is pointed in the wrong direction when reinstalling it?
do you have thermistors 1 and 2 plugged in to the correct connectors?
have you done a firmware update to the latest version?
just some things for you to check.

[SmellsHot]

Re: Bizhub 421 with recurrent C-3902 Errors

Sounds like you answered your own question. Fuser is getting too cold and has a tough time warming up. A simple cold breeze in the right spot can through fuser codes. I've seen this with an open window in winter.....I'd shut off the low power/sleep mode and see if it codes out then.

[pepper38_cnd]

Re: Bizhub 421 with recurrent C-3902 Errors

Keep it simple. You say it doesn't get very cold there, but the operating specs are 10-30C or 50-86F. Tell your customer to set their night time thermostat to 55F or 13C and you won't have a problem if they shut the heat off totally at night and the temp drops to say 45F it may be warm when they arrive but the fuser roller inside the machine is still at 48F and can't warm up fast enough. Other wise turn off Sleep mode set the machine for Low Power Mode and instruct the customer never to turn it off.

[SmellsHot]

Re: Bizhub 421 with recurrent C-3902 Errors

Forgot to mention for 15$ at a local hardware store you can go and grab a little handheld temperature and humidity thing. I'd set that right next to the machine. Ours can record record highs and lows.....It's come in handy at a few places.....

[PeterG]

Re: Bizhub 421 with recurrent C-3902 Errors

Thanks for the replies guy's. It is interesting to note . Although I am aware that the machine is being operated out of spec. We have other machines here operating under similar conditions, no problems. I am afraid telling the customer to leave the heaters on overnight would not go down well here. I think it must be an Australian thing. If you can only use the copier between 10-30 degs, it would mean the machine would be out of action for 6 months of the year. I will try turning off sleep mode. If that doesn't work, I guess they are just going to have to accept the "out of spec" info. Thank's again fella's, it's good to run this stuff past like mind's.