Why ask why? #2

[blackcat4866]

On e Studio 853, I was getting grainy light images like undertoning, but the developer was at less than 1/2 yield. It's a fairly dusty location, and I've cleaned laser slit glass and/or laser optics before on other machines at this location, so I started there first.

Here is where it gets interesting. When I booted up, the machine went into an add toner cycle for nearly 2 minutes. The resulting images were nicely toned.

I've dealt with potential control issues before with Canons. I do know that potential control often regulates developer bias, primary charge, transfer charge, separation charge, toner density, laser intensity.
So here's the question: What does a dirty laser slit glass have to do with toner density? =^..^=

[NeoMatrix]

Re: Why ask why? #2

Re. Grainy ?
Is the developer(ferrite) coming out on the copies ?

Is the copy coming out grey scale?

Dirty slit glass interferes with the laser writing the latent image on the drum, which equates to charge density on the drum, an therefore how much, or how little, toner is attracted to the drum.

I not sure I've answered the question...

[Iowatech]

Re: Why ask why? #2

That is weird. As lack of laser equals lack of image, you'd think that a less dense drum condition sensor pattern (I've only worked on analog Toshibas, not sure what the correct technical term is for that) would create an overtonered condition.
I was going to say something about drum ground, but from what I've seen that doesn't cause the developer to become undertonered, the drum only attracts less toner than it should then.
You've started a fine mystery story here. I look forward to seeing how it ends.

[allan]

Re: Why ask why? #2

Like the KM B600 there is no TD/TCR sensor. It leaves the control up to the ID sensor. A dirty still glass would have the same effect as a dirty optical sensor. B600 will overtone trying compensate.

[Mr Spock]

Re: Why ask why? #2

Like the KM B600 there is no TD/TCR sensor. It leaves the control up to the ID sensor. A dirty still glass would have the same effect as a dirty optical sensor. B600 will overtone trying compensate.

I agree. This machine calibrates the toner off a toner density patch off the drum. If the laser is dirty then less toner causing the machine to "pull" more toner out of the dev unit. Cleaning the laser gives a better defined patch and dev tones back up.

[bryand]

Re: Why ask why? #2

I've had luck just running 05-290 when these machines get light copies.

[SalesServiceGuy]

Re: Why ask why? #2

Make sure there is not a light layer of dust on the thermistors. This cause "image quality" and "wait warming up" issues.

[blackcat4866]

Re: Why ask why? #2

Make sure there is not a light layer of dust on the thermistors. This cause "image quality" and "wait warming up" issues.

It also means that your thermistor isn't touching whatever it's supposed to, because light dust would rub off if there was contact. =^..^=

[Desert Rat]

Re: Why ask why? #2

What I usually see is that the dirtier the optics the lighter the copy. When I wipe the laser slit glass I also clean the scanner
mirrors, reflectors, ccd lens and bottom of platen glass. Heat from the lamp creates enough static to attrack dust to the bottom
side of the platen glass.
So are we to understand that this happens in copy as well as print mode?


DR

[blackcat4866]

Re: Why ask why? #2

Yes correct. =^..^=

[Desert Rat]

Re: Why ask why? #2

It sounds like it's having trouble keeping up with demand. When it is turned on it adds toner. I have seen where the recycle sub hopper can get so packed with toner
that it would code out. May be this is the prelude.
Generally I see this happen because I run the developer more than it is rated for. Usually I see a build up of toner between the drum and the developer unit.
It causes black streaks more often than not. But if you're changing the dev mix closer to rated use I could see where the recycle sub hopper could bind up
because of the packed toner.
It's not that hard to cure, just messy. Have a plastic bag for toner and big drop cloth & vacuum.

DR