Replaced everything but the cabinet hp 8150n

[byteabit]

I've been messing with this thing for way too long. Not finding any help anywhere, especially HP. The issue is this:

Simplex printing is flawless. However, when printing duplex, a dark gray line runs down the middle of side 1. With multiple prints using duplex, the problem worsens and starts affecting the second side as well. I have changed the....

fuser (twice - 1 w/ full maint kit)
toner (three times)
HVPS
duplexer
scanner assembly
DC controller

Paper is standard, printer is squeaky clean. Any suggestions?

[cs_steve]

We have seen some cheap transfer rollers do this ... was it an OEM genuine HP transfer roller or an aftermarket?

[byteabit]

OEM, right out of the HP kit (also changed twice btw). And, since single sided is not affected, I didn't hold out much hope that it would cure the issue. I'm really perplexed. I tore that whole unit apart looking for something in the duplex path that would cause this... but nothing. So, here I sit... turning to this forum and waiting with baited breath for some miraculous epiphany. :)

[cs_steve]

Hopefully you're double sure the transfer roller is genuine HP (the reason I stress this is the only time we've seen this exact problem with duplexing-only print defects is from cheap aftermarket transfer rollers)

If the transfer rollers are genuine HP, I would suggest perhaps it's a bad batch of toner cartridges (I realize you've tried 3). If they aren't OEM cartridges; I'd try a different brand, preferably HP.

You've basically tried the other major possibilites (duplexer, DC, high voltage). The only other board is the low voltage power supply.

Usually when the issue starts seeming complicated, it turns out not to be :-) Perhaps it will be as easy as switching toner vendors and see what happens.

[MichaelTech]

If it is just down the middle, then the only roller it can be is the duplexer. But you changed that.
However, a weak H/V may cause the toner to react this way when the paper reverses.
Check the registration assy. underneath, and the feed rollers in the PIU assy.

And that's "bated" breath. Baited would have to have an anchovie on your tongue! Ha!

[redcow]

Remember, when the 8150 is in duplex mode side 2 is printed first, then the sheet gets fed back in to print side 1.

That being said, whatever is happening is occurring before the paper reverses.
With that I leave you to flounder with your printer. ;)

[byteabit]

You mean *after* the paper reverses Redcow.... since side 1 is the one with the line. Thanks! I'll keep that in mind! :rolleyes: LOL. I guess I'm going to try Michael's suggestion. Including noting the difference between baited and bated breath! I imagine that would be an unpleasant mistake! The transfer rollers are in fact genuine HP. However, the toner cartridges are not. Unfortunately for me, I'd have to purchase one of my own in order to test the theory. I'm working for a very large bank that prides itself on pinching pennies...

Thanks all! Will let you know if this EVER gets resolved!