My first #MARCHintosh project this year... an original LaserWriter! I've had this printer a long time, but have never gotten it to work.
Some time ago I fixed the print engine, it was a single bad resistor in the fuser control.

I had it apart long enough I lost the ribbon cable between the DC controller and logic board. Thanks to a photo from @bitsavers I discovered why I'd had such problems getting it to do anything: the connector on the logic board is labeled backwards!!

So now the problem is the logic board crashes over and over trying to do "bitshift". I verified the ROMs are OK. I stacked a known good ram across the entire bank... no change.
I suppose the next step is to start desoldering the RAMs? 😕

Welp. So far they're all ok.

I re-stuffed the rams. Burnt another set of ROMs... same result. 😕

Btw, I got the rom images from @keelan. Thanks!!
Interestingly with the switch in special the top 2 ROMs are the most busy.
I did discover with the switch in AppleTalk it is trying to start though! You can see it switch node # from 170 to 223. (Then it reboots).
I'm wondering if the configuration rom is screwed up. I think is where I'll look next.

Ya, I don't think much is happening outside this 128k of code.

I socketed the eeprom. I was able to read it, and rewrite it. But now I've caused a lower level fault and the machine doesn't even start to boot, it just spits an error code out on the 25 pin port. This means I've reached the troubleshooting stage where the device is getting more broken 😠

Welp, this auction had good timing. Nobody bid against me!

The board arrived!! It didn't work when I got it. I think the ROMs are bad. I found one with a bent pin, but had to swap in the set I burnt earlier....

Signs of life!!!
With some coaxing of the paper past the missing pickup rollers, it prints!!
This is the first time this machine has done anything in the 10 years I've had it.

Now to replace the pickup rollers. Man this thing is a PITA to get at!!! You have to take the whole guts of the printer out of the bottom tub! I made new tires by cutting up a rubber band and gluing it to the "wheels". It works!

Now how does Humpty Dumpty go back together again?
I take back anything mean I ever said about the LaserWriter II having too many screws.

Now for the separation rollers.

It lives! For the first time it probably 20 years it's able to feed paper on its own 😇

I took the toner cartridge apart to see if I could improve it. Looks like it was refurbished in 1990! Plastic push pins hold it together. The durum cleaning wiper had completely disintegrated. Someone from Reddit has a spare they're sending me 😇

I have 2 NOS cartridges... which expired in 1997. The wiper in one was still there, but is hard as a rock. I'll put the new wiper into this cartridge.
PS: isn't the page count odometer cute? It has at least 8 gear reduction stages.

Ok, I had to combine the drum from a NOS cartridge, developer from the 1990 cartridge, and install a new wiper blade. But it's printing about as good as new now!

@compu85 Awesome!! Looks great. You’ve put lots of effort into this machine- congrats!