bizhub 751 spewing toner.

[allan]

Re: bizhub 751 spewing toner.

Update to my under-toned 601, I noticed after cleaning out the developer unit that the blue loctite was flaking off of the Developer Regulation Blade. Had a friend mail me a very used, but functional developer unit and after performing the PM & drum replacement, Fatso is running like new!

Only took 2 or 3 PMs to figure that one out...

Jip, I get a lot of these machines second hand. Good machines, but they can be really random at times.
Like you said it takes about a half a million clicks to get all the kinks out of some of them.

[Synaux]

Re: bizhub 751 spewing toner.

Jip, I get a lot of these machines second hand. Good machines, but they can be really random at times.
Like you said it takes about a half a million clicks to get all the kinks out of some of them.

Yea...when they run they run. Even with the kinks, this particular machine ran over 120k in a weekend without a single jam. Before I figured out the undertonning issue, I was tempted to suggest an upgrade to a 652 or even a c652. However, given the used machines I was looking at had over 400k, the tranf belt, fuser, and drum would have to be replaced soon relatively soon--which would cost more than the machine itself--the 652 engine is superior in my opinion, but simply more expensive to maintain.

As a side note, I recently started disconnecting the toner recycle clutch so the recycling contraption runs at all times (there is a dip switch too--if you want to deal with that). I find that the tube gets crammed with 'rocks' of toner...hopefully this method will eliminate that issue.

[bronco31]

Re: bizhub 751 spewing toner.

i think i found a fix too...
in drum pec adjustment ... set the LD1 and 2 offset to be plenty dark in between the 2 lines when printing out the test chart on letter R or legal....
i think that then causes the patch formed on the drum (it does that right?) to be a pinch dark so the machine decides to not add so much toner to the mix!

[allan]

Re: bizhub 751 spewing toner.

I will give that a try.

[Synthohol]

Re: bizhub 751 spewing toner.

Hello, I signed up just to reply to this thread.
I have serviced these hundreds of times and the toner spew can be avoided or at least reduced to a minimum
I only want to suggest pretty much what is in the book.
sometimes its best to start from scratch. if you replace the drum and developer blow off all toner from AIDC sensor board with an aircan, a vacuum can cause it to short out. reset the counters, set the proper drum grid manual charge voltage with a good meter, adjust to what the voltage is stamped on the back flange of the drum (usually in the low 700V range) then run through the auto max density adjustment, laser diameter, do the LD1 and LD2 adjust so there is just a faint box just over the first line. then cart install mode print the 10 sheets.
the bit switches mentioned earlier do help but i would set them after doing these adjustments.
the bad part about the toner dumping is when it collects on the web and grinds a stripe in the UFR!
i actually miss working on these big dinosaurs, now everything these days you dont need the finesse you did long ago.
I hope i've helped.

[Synaux]

Re: bizhub 751 spewing toner.

Yeah, yeah, I know this post is ancient, but holy cows, I just discovered a heck of a mess on the 601 I was originally referring to in this post (that I sort of hijacked)!
Anywho, here is my newest story (read for leisure):

This machine has and will historically undertone for the past several years--no biggie though--run the load checks (1, 5, 50 for ~10 sec and repeat as necessary). Why the toner reservoir continues to deplete, will most likely forever be a mystery--especially when considering the coverage on prints is quite low.

Anyways, I get called in twice in one week which is a little crazy as I would only have to "spike" it when I go to clean/check it every 6months or so.

First visit: The PM is actually nearly 3x the life, but so what! Right!? Because the coronas, drum, web (these will fail at ~250k unless you take emery cloth to the rear spring shaft and grease that POS--FYI) were all still good and when it is toner-upped, the prints are perfect--even halftone. Dev was MEH, but quality was great so I let it be. Now, I did replace the cleaning blade in a rush (because it was running very dirty) so what I found on the second visit certainly might have been overlooked.

Second visit: Only 500 additional clicks. Do the same load checks--PQ perfect (yay!)
Stick around and chat with the owner and drink a beer (after hours--lol) as he ran off about 3 reams of paper and lo and behold the it undertones again. He was running off letterheads...
So with a beer in one hand, I do the same load checks, run test pattern 12 100x and same reemerges. So I dig deeper and find that about half of what I am going to call the toner-screw-spring-agitator (I am too lazy to look up the proper name) was toner-welded to the housing (not the delivery tube, but the agitator that runs parallel to the drum). After about an hour with a chisel and hammer I finally got it removed and cleaned the housing.
This also caused portion of toner delivery tube housing to melt...

Not really looking for a fix or anything just wanted to share this. The guy is grumbling about replacing the machine. When I told him that aside from what he pays me and toner, nearly 750K for about $300.00 for a PM is pretty dang good! Also the only jam history were in the ADF lol...