Ricoh MP 7500 -Copies with dark background

[kalaris]

Hi. Ricoh MP-7500. Copies with dark background and dusting from the group development. I replaced the developer and the problem has come back after a few thousand copies. Some experience on this problem? thanks

[Zaxxon]

Re: Ricoh MP 7500 -Copies with dark background

Did you clean the magnetic roller when changing developer?

Vaccum and clean drumunit, check drum state, charge corona and grid.
DO NOT VACCUM DRUM POTENTIAL SENSOR...

[ptrflrs]

Re: Ricoh MP 7500 -Copies with dark background

Agree with zaxxon. from experience these turds usually go light with old developer. Dark copies probably caused by grid/charge or dev bias or even a bad brush roller. Did u put the development filter back on? Worth checking the erase leds under the drum, the density sensor just below the blade and the shiny potential sensor zaxxon mentioned

[allan]

Re: Ricoh MP 7500 -Copies with dark background

Did you initialize the developer?

[slimslob]

Re: Ricoh MP 7500 -Copies with dark background

Check continuity between the drum shaft ground connector that goes to the developer HVPS and the drum shaft. the reading should be less than 10 ohms. Rotate the drum shaft slowly and check if all the way around. If it measures above 10 ohms, replace the drum shaft holder assembly. The ball bearing in the shaft holder is supposed to be conductive and packed with conductive grease. The conductivity of the bearing breaks down and the drum does not charge correctly. Also during drum condition check portion of process control, that lead from the HVPS is used to apply voltage to the drum. This will lead to background and drum charge SC codes accompanied with partial or total black copies. Been there, done that.

[Codex]

Re: Ricoh MP 7500 -Copies with dark background

Hello

I have the same problem with to MP 6500 and one MP 7500, at the same customer, developer and drum replaced one month ago, but the copy/print quality is bad, like gone developer, i checked the VT value and in all three machines it goes from 1.45 V to a maximum of 1.62 V, it seems the machine is in overtoner.....
but it isnt, the copy is light, blurred and the lines are not sharp. see attachment. The developer is NEW and initialized correctly, the Drum was changed with the developer (Original Ricoh D58).

[allan]

Re: Ricoh MP 7500 -Copies with dark background

That looks like a development Bias problem or the charge on the drum is way to low. Looks tweaked.

[kalaris]

Re: Ricoh MP 7500 -Copies with dark background

I happened on other machines this problem and cleaning filters and drains and replacing again the developer has ripristinato.Ma latter is more stubborn and despite having replaced crown and grill, developer drum, continues to create problems dark background, as if it went actually overtoner.

[Codex]

Re: Ricoh MP 7500 -Copies with dark background

Today i cleaned the magnetic rollers with a metal brush, and the quality became a little bit better..... Then i checked the bias board and the charge unit...cleaned the toner hopper and the drum earth... Everything ok.... The strange thing is that the Vt in all three machines is lower then 1.80 V.....

[wester]

Re: Ricoh MP 7500 -Copies with dark background

Today i cleaned the magnetic rollers with a metal brush, and the quality became a little bit better..... Then i checked the bias board and the charge unit...cleaned the toner hopper and the drum earth... Everything ok.... The strange thing is that the Vt in all three machines is lower then 1.80 V.....

Just a thought, have you checked into the transfer belt and its rollers? These have a tendancy to build up with toner.

[Iowatech]

Re: Ricoh MP 7500 -Copies with dark background

I don't know how much this will help, but what is the machine's usage?
If these faster machines aren't used enough, the toner motor isn't on long enough to keep up which can lead to output quite similar to Codex's .pdf example.

[Codex]

Re: Ricoh MP 7500 -Copies with dark background

The machines are in a copy shop.. And running the whole day.... I changed transfer belts and cleaned the transfer rollers, the machines are running with Type 9002 toner, earlier type 6210,ricoh says it's the same.....