Laserjet III 50 Error

[dh]

I've got the 50 error and I've read the newsgroups so I know some things
that can cause this.
Here's the troubleshooting done so far:

- Replaced AC supply with referb (www.printerworks.com).
- Fuser lamp measures good (approx 0 ohms).
- Thermistor measures good (approx 1300 Kohms).
- Thermal switch is closed ( 0 ohms).
- Without fuser in the printer (case open switch actuated) I measure line
voltage (approx 120 VAC) at the fuser power feed.
- With fuser in printer (and case open switch actuated) I measure 0 volts.
No AC is being delivered to the fuser and fuser never glows.
- Replaced the thermistor and its circuit board with one from an other fuser
assembly, but that fuser was shot so I've no confidence that the
thermistor/PCB is good.

In short it appears the AC supply is never getting "permisson" to power up
the fuser.
Any ideas, and any measurements I can make to confirm the possible problem?

Thanks,
David

 

[Keith]

I had that error on my IIID. Bought parts fom a company called
'printerworks" or something like that. Job was easy, about 15 minutes...

Good luck

 

[RWatson767]

David

Laserjet III 50 Error

In short it appears the AC supply is never getting "permisson" to power up the
fuser.
Any ideas, and any measurements I can make to confirm the possible problem?


The fuser can be inserted/installed with the left hand connector off by a pin.
Make sure the pins on the fuser connector match the sockets on the chassis.
Bob AZ

 

[dh]

Thanks. I've bought a number of parts over the years from Printerworks and
have been pleased with their service.

 

[dh]

I've tried to be careful to make sure all the pins lined up, but perhaps I
missed something.
I'll check again.

 

[dh]

I purchased a service manual on-line at 2manuals.com and per the
instructions checked the DC supply voltages (+24, -5, +5). All appear good.
Guess I'll double check to make sure the connections are correct. If all
else fails I'll probably order a new fuser.

 

[magpie]

I purchased a service manual on-line at 2manuals.com and per the
instructions checked the DC supply voltages (+24, -5, +5). All appear good.
Guess I'll double check to make sure the connections are correct. If all
else fails I'll probably order a new fuser.

Um, sorry I didn't see this post earlier. This is fairly common with
the HP-II's and III's. First thing to check is the Upper Cooling Fan
that sits on top of the AC Power Supply. If it turns on and works when
you power up the printer, then it's OK. If it doesn't turn on and
work, check to see if it's frozen or seized up. If so, replace. I
learned many years ago, quite by accident, to check the fans first.
Hope this helps.

Frank

 

[fred smith]

what are you trying to print , if you don't have enough memory installed
it can give you weird errors . if not it could be the DC controller