On Tue, 23 Feb 2016 09:13:00 +1100, Trevor Wilson
wrote:

**Good news bad news time. I now have the service manual for this
device. No useful schematics. Just block diagrams and hundreds of pages
of mechanical drawings and photos. Quite comprehensive in it's own way.
The good news is that I now have a proper interpretation of the fault code.

50.8 = Low fuser temperature (Subthermistor)

Thank you for delivering the error message.
http://www.all-laser.com/a50service/
I've seen that error message on other model HP printers. In my
experience, it can be anything from a loose connection on the ends of
the ceramic slab heater element, to cracks in the heater element.
Also, caked on toner onto the thermistor temp sensor will cause a low
temp reading. Measure the resistance of the heater element from end
to end and you should see about 15 for 117V and twice that for 220V. I
think I know where I can find a 3800 to measure, or just ask in the HP
forums or FixYourOwnPrinter forums.

This article suggests that it might be low line voltage:
http://www.fortwayneprinterrepair.com/wordpress/2011/11/06/hp-color-laserjet-3000-3600-3800-and-cp3505-50-1-fuser-error/

Also see:
http://www.fixyourownprinter.com/posts/42184
I'll try to find the unspecified service note, but so far, I'm not
having any luck finding it.

Meanwhile, dig through this mess on 50.1 errors and see what you can
excavate:
https://www.google.com/search?q=hp+color+laserjet+50.1+fuser+error

Would I be crazy to buy one of these?
http://www.ebay.com/itm/RM1-2764-RM1...AOSwnDxUgFp 3

Good find. I missed that one. Yes, that should work for 220V. I
checked the numbers. Since the rebuild kit does NOT include a heater
element, the replacment from China may be your only reasonable option.

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