On Wed, 6 Mar 2019 08:15:35 -0000, Mike Coon
wrote:

In article ,
says...

I fix both Brother and HP laser printers. ...

In that case, can I ask your opinion about a problem with an HP color
laserjet 3500.

Yes, but next time start a new thread when you change topic.

I fixed the problem it was handed to me with. (Sticky
solenoid #4, determined by error message and explanation found on the
web.)

Common and well known problem that HP didn't bother fixing for many
years:
http://www.learnbydestroying.com/jeffl/hp2200/hp2200.html
http://www.learnbydestroying.com/jeffl/hp4200/hp4200.html

But then find that it prints smeary. You can see smears that arise from
the alignment patterns placed (but not meant to be printed) down each
side of the transfer belt. And also from previoius printing. So maybe it
is just inadequate gleaning of toner from the belt. But I cannot see how
to fix that, short of a new belt unit. Since this is just a freebie
being upcycled it does not warrant much, if any, expenditure...

A really dense colour picture looks great because the smears are hidden!

Cheers, Mike.

I have no idea what might be wrong. If the big transfer belt is
constantly dirty, it's because something is dumping toner on it. It
could be leaky toner carts, dirty belt, waste bin is full, etc. It's
the wiper because that would cause vertical streaks. Clean it out
with an air compressor before you go any further. The belt is
sensitive to light and excessive exposure to direct sunlight can kill
it.
https://www.ebay.com/itm/Q3658A-HP-COLOR-LASERJET-3500-3700-TRANSFER-KIT/352521542553

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558