MPC-7500

**T911** · 09-10-2012

This one has me for a loop. I can't watch and see what is going on. I looked into the pc units and transfer area to see visually if anything is out of wack but all looks good. Machine has 270k bw and 154k color on it. i don't see a staull and don't here any noises for brocken gears. image as you can see is there but just blurred. view attached file. thanks

**Bantams** · 09-10-2012

Funny enough I had this same issue 2 days ago after the Customer had left the front door open and Light had got onto the Black Drum.

After doing a few Hundred Copies it went back to Normal Try Individual Col copies ie do a copy in cyan yellow and Magenta and then do one on black only and i bet the single col copies are not blurred and the Blk one is.

**tjvincent** · 09-10-2012

That looks like humidity, did you run a bunch of copies ? Try single color cyan, mag, yellow. I have seen that in small offices after a weekend, it goes away after it is run a bit.

**Llama God** · 09-10-2012

Are the PMs all up-to-date?

**BLADE** · 09-11-2012

looks normal to me

**fbkhan3** · 09-11-2012

Looks like, Time to rebuild the black PCU!lubricant bars,Springs,
(MPC 7500)these beasts are known for CQ issues,PM Unit's always way less then 450K,

**turbojetboy** · 09-12-2012

Originally Posted by fbkhan3

Looks like, Time to rebuild the black PCU!lubricant bars,Springs,
(MPC 7500)these beasts are known for CQ issues,PM Unit's always way less then 450K,

Thats the answer, and you should replace the black coro unit - as it is my experience that changing this along with cleaning or replacing all the air filters will go a long way towards stopping the exact problem of blurring your sample shows.

**Masterchief** · 09-12-2012

Originally Posted by Bantams

Funny enough I had this same issue 2 days ago after the Customer had left the front door open and Light had got onto the Black Drum.

After doing a few Hundred Copies it went back to Normal Try Individual Col copies ie do a copy in cyan yellow and Magenta and then do one on black only and i bet the single col copies are not blurred and the Blk one is.

I agree with this post, i also had this problem solved by doing this procedure

Masterchief

**BLADE** · 09-12-2012

This thread is quite remarkable and unlocks some of the issues with this model. I,ve seen the condition on the sample also after having the pcu out for a few minutes during a call. Wasnt sure what was going on but the copies came good after about 200 copies.

I think that indicates the drums are over sensitive to light.

Are there any old Canon techs here from the NP4835 analog series? Those machines were released with a drum that 'went off' when exposed to outside light (faded patches). But more importantly they suffered 'light fatigue' during normal use from the exposure lamp and that model had a new invention which was a laser to do the lead edge blanking. The drums fell way short of their target. A few months later new drums were issued and the machines ran good.

I reckon the same thing is happenning with this model. The process control aint happy and amps everything up trying to get solids up, so you end up with overtoning, all because of a weak drum. 2 cents worth.