Diagnose a NeXT 400dpi Laser Printer

Started by bobo68, February 24, 2016, 08:51:35 pm

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bobo68

Hi,

I have NeXT 400dpi laser printer that looks very good from the outside. When I print something the job lands in the PrintManager which says "printing". But the printer never starts printing. The printer starts up together with the NeXTstation and its fan is blowing. When I take out the paper tray the NeXTstation tells me that paper is needed.

So the computer and the printer are connected and can communicate.

What can be done to diagnose the problem? Where can I see the status of the printer and error messages?

TIA
bobo68

bobo68

I did more analysis but the printer would still not print. :-/

The printer reacts to nppower on/off commands. It also is able to communicate back its status (dialog saying no paper or hood open).

I disassebled it and found the "magic" test print button (it is on the pcb on the underside). Although the service manual says it would print a test page if you press the button, it does not. :-(

I'm still searching for a way to get a more expressive status from the printer. Do I have to hack a C program do get it?

NeXTnewbe

Quote from: "bobo68"I did more analysis but the printer would still not print. :-/

The printer reacts to nppower on/off commands. It also is able to communicate back its status (dialog saying no paper or hood open).

I disassebled it and found the "magic" test print button (it is on the pcb on the underside). Although the service manual says it would print a test page if you press the button, it does not. :-(

I'm still searching for a way to get a more expressive status from the printer. Do I have to hack a C program do get it?


can you share the service manual, please

bobo68

It is right around the corner: http://www.nextcomputers.org/NeXTfiles/Docs/Hardware/NeXT%20400%20DPI%20Laser%20Printer%20Complete_OCR.pdf. Keep in mind that this is for LBP-UX engine printers, there are some differences to the NeXT laser. E.g. 2 compared to 3 screws holding the upper cover and the front cover assembly.

Then there are http://www.nextcomputers.org/NeXTfiles/Docs/Hardware/NeXT_Laser_Printer_Service.pdf and http://www.nextcomputers.org/NeXTfiles/Docs/Hardware/NeXT_Laser_Printer_Tricks.pdf.

bobo68

I had some success. Found a utility named printer preferences ("PP") on a NeXT PD-CD. It show the status of the printer and allows to make some settings.

After I fed the printer with fresh paper it started to print but would not be able to pull the paper through (exept for one time).

Here is an interesting maintenance video for the printer: https://dl.dropboxusercontent.com/u/1429222/Videos/nextprinter.mov (can somebody copy it to the file area?).

Rob Blessin Black Hole

Quote from: "bobo68"I had some success. Found a utility named printer preferences ("PP") on a NeXT PD-CD. It show the status of the printer and allows to make some settings.

After I fed the printer with fresh paper it started to print but would not be able to pull the paper through (exept for one time).

Here is an interesting maintenance video for the printer: https://dl.dropboxusercontent.com/u/1429222/Videos/nextprinter.mov (can somebody copy it to the file area?).


Hello : I just uploaded it here :  http://www.nextcomputers.org/NeXTfiles/Videos/   Best Regards Rob Blessin 8)
Rob Blessin President computerpowwow ebay  sales@blackholeinc.com http://www.blackholeinc.com
303-741-9998 Serving the NeXT Community  since 2/9/93

pentium

QuoteAfter I fed the printer with fresh paper it started to print but would not be able to pull the paper through (exept for one time).


It's quite normal for the intake rollers to lose their ability to grip the paper. I believe Rob still has a stock of replacement rollers.

-NeXT 68040 Cube with NS 3.3 and 64Mb ram

Rob Blessin Black Hole

Quote from: "pentium"
QuoteAfter I fed the printer with fresh paper it started to print but would not be able to pull the paper through (exept for one time).


It's quite normal for the intake rollers to lose their ability to grip the paper. I believe Rob still has a stock of replacement rollers.


The 2 most common failures are the intake roller , yes I have new ones Intake roller $15 and exit gears loosing teeth so paper doesn't go all the way through exit gear $10 ,  Also have plenty of new old stock intake paper trays both regular and legal size $20 or used $15 and exit trays $15 new or $10 used also NeXT Logo printer data cables $15 , Shipping on any of above is $7 US and $20 First Class international, they just raised USPS priority small box rates to the $33.95  .... they have been raising rates almost weekly lately.  Best Regards Rob
Rob Blessin President computerpowwow ebay  sales@blackholeinc.com http://www.blackholeinc.com
303-741-9998 Serving the NeXT Community  since 2/9/93

rockus

Greetings,

I recently acquired a NeXTlaser for my TurboColor and it had the same symptoms:
- starting up when a print job was placed in the queue
- the queue saying Printing...
- but never doing anything
- not even with the infamous test button on the bottom side

Over the last couple weeks I worked on the problem on and off and dug deep into the electronics and test modi and even built myself a diagnostic unit that could be connected to the diagnostic port on the underside.

So, what was the culprit? It's the 210degC thermo safety switch that's failed open. I could revive the original one by freezing it for 2 days. But then it only worked once.

So I sourced around and found replacement parts and yesterday night I replaced it - together with a bit of patching the mounting, though.

I put in this one:
Honeywell 3450RC 80040501
(e.g. Mouser 785-3450RC-80040501)

If wanted, I can post photos of how I mounted this in the printer. The original mounting can't easily be used. But the most imporant part: it's printing again!

[Since the printer hadn't been used for months at least, I still need to do cleaning, though]

---

I also had then the problems of the paper not being pulled in properly. This was simple: the little switch, that detects if paper is in the tray, sometimes was stuck in the down position and prevented the paper from being pushed up completely against the intake roller. Once I made sure to always push that little switch up, the intake was fine.

Hope that helps,
Oliver

Rob Blessin Black Hole

Quote from: "rockus"Greetings,

I recently acquired a NeXTlaser for my TurboColor and it had the same symptoms:
- starting up when a print job was placed in the queue
- the queue saying Printing...
- but never doing anything
- not even with the infamous test button on the bottom side

Over the last couple weeks I worked on the problem on and off and dug deep into the electronics and test modi and even built myself a diagnostic unit that could be connected to the diagnostic port on the underside.

So, what was the culprit? It's the 210degC thermo safety switch that's failed open. I could revive the original one by freezing it for 2 days. But then it only worked once.

So I sourced around and found replacement parts and yesterday night I replaced it - together with a bit of patching the mounting, though.

I put in this one:
Honeywell 3450RC 80040501
(e.g. Mouser 785-3450RC-80040501)

If wanted, I can post photos of how I mounted this in the printer. The original mounting can't easily be used. But the most imporant part: it's printing again!

[Since the printer hadn't been used for months at least, I still need to do cleaning, though]

---

I also had then the problems of the paper not being pulled in properly. This was simple: the little switch, that detects if paper is in the tray, sometimes was stuck in the down position and prevented the paper from being pushed up completely against the intake roller. Once I made sure to always push that little switch up, the intake was fine.

Hope that helps,
Oliver
Very cool, yes pictures would be great ! .... the little switch.... is this on the paper try or internal  a photo of this would help !  Best Regards Rob Blessin
Rob Blessin President computerpowwow ebay  sales@blackholeinc.com http://www.blackholeinc.com
303-741-9998 Serving the NeXT Community  since 2/9/93

rockus

These are the photos of the thermo switch and my mounting. It's intended as preliminary. But as things go, it'll probably stay that way...

Ideally, from a historian's point of view, I would find out how to get the original mounting out of the point-welded assembly so I can re-use it...





Oliver

rockus

With "little switch" I meant the paper sensing switch on the tray side of the printer. The one, that's in focus on this picture, looking into where the tray slides in (is this the "tray bay", then? ;) ):



Oliver

barcher174

I'm curious about this diagnostic unit you connected. Can you share more details?

Thanks,
Brian

Rob Blessin Black Hole

Quote from: "rockus"With "little switch" I meant the paper sensing switch on the tray side of the printer. The one, that's in focus on this picture, looking into where the tray slides in (is this the "tray bay", then? ;) ):



Oliver
Great work Oliver, this may have been one of the main causes of the last 20 year of the NeXT laser printer apocalypse   ,may be you pulled the sword from the stone of sorts.

At any rate, I'll give it a go .... for many moons we have been driven nuts by the paper is jammed in your printer .   Replacing intake rollers often didn't seem to resolve this even with some pristine printers so I gather if I make sure that level is open or flipped back toward me,  I may be in business at least on some of these printers.   In reading through the factory Laser docs below page 2-27

D . Paper Jam Detection
The delivery unit paper sensor (PS331) detects whether paper s feeding normally
.
The microprocessor
(M- CPU)
determines
wheth~r paper is jammed by checking whether paper
1s present or absent
at the sensor at times stored in memory
.
.
1)
Paper does not reach
_the delivery un1t
paper sensor by the required time
.(Delivery unit delay jam)

........

Here is the Laser Printer doc in full http://www.nextcomputers.org/NeXTfiles/Docs/Hardware/  

Thank you !

:D
Rob Blessin President computerpowwow ebay  sales@blackholeinc.com http://www.blackholeinc.com
303-741-9998 Serving the NeXT Community  since 2/9/93

rockus

Hi Rob,

Quote from: "Rob Blessin Black Hole"Replacing intake rollers often didn't seem to resolve this even with some pristine printers so I gather if I make sure that level is open or flipped back toward me,  I may be in business at least on some of these printers


That lever needs to be rotated up/inwards into the printer. I don't quite get if that is what you meant with "flipped back towards me".

Oliver