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Help Troubleshooting an LC II

BetaC

Member
Earlier today, I managed to pick up an LC II. Once I got home, I opened it up, and cleaned out what dust had collected over the years, then went to turn it on. I currently don't have a DB-15 to VGA converter to allow me to get video out of it, but I thought I should at least plug it in to make sure that I get anything. Currently speaking, all that I am getting from the device when I flip the switch on the PSU is a quick noise from the Floppy drive, and a flash from the LEDs on my ADB keyboard. Using the power button on said keyboard doesn't do anything. I have also checked if switching in a known good PRAM battery would work, but it didn't change anything. I haven't noticed any gunk around the capacitors, but I can slowly swap them out if that's going to be the source of the problem. 

 

Scott Baret

Well-known member
You'll also have to re-cap the power supply. I recommend re-capping both the logic board and power supply, which should solve your problems.

 

cheesestraws

Well-known member
The power button on the keyboard won't do anything much on the LC II, it's a hard power switch.

I've had a couple of those boards that looked cosmetically fine(ish) but recapping brought them back to life.  So while it's not certain that's the problem, it's definitely a likely problem.

Do, as @Scott Baret says, look at the power supply too.  The third common failure, I think, is the Egret chip getting contaminated with cap crap, and that's a bit more of a pain to deal with.  But those three failure modes account for a lot of the dead LC IIs out there.

 

BetaC

Member
You'll also have to re-cap the power supply. I recommend re-capping both the logic board and power supply, which should solve your problems.


The power button on the keyboard won't do anything much on the LC II, it's a hard power switch.

I've had a couple of those boards that looked cosmetically fine(ish) but recapping brought them back to life.  So while it's not certain that's the problem, it's definitely a likely problem.

Do, as @Scott Baret says, look at the power supply too.  The third common failure, I think, is the Egret chip getting contaminated with cap crap, and that's a bit more of a pain to deal with.  But those three failure modes account for a lot of the dead LC IIs out there.
Thank you both. I am waiting for the DB-15 adapter to come in so I can get video out, but I managed to recap the board and power supply. All seems well so far, since I get a happy chime. Now to just find a SCSI power cable.

 

cheesestraws

Well-known member
The 4-pin to Molex cable that is missing for some reason in my LC-II.


The 4-pin end is just a 4-pin Molex Mini-Fit Jr.  Easy to get hold of.  Nothing esoteric at all.  I've made up replacement cables in the past pretty straightforwardly :) .

That said, if you're going to scsi2sd this it's not worth it, really; that is low-enough power that it doesn't need an extra power cable in an LC II, it will run from the power it can derive from the data cable.

 

BetaC

Member
The 4-pin end is just a 4-pin Molex Mini-Fit Jr.  Easy to get hold of.  Nothing esoteric at all.  I've made up replacement cables in the past pretty straightforwardly :) .

That said, if you're going to scsi2sd this it's not worth it, really; that is low-enough power that it doesn't need an extra power cable in an LC II, it will run from the power it can derive from the data cable.
Okay, I will then try to figure out how to make a cable in case I need it in the future. I managed to get the computer booted up via having my Pentium MMX system running next to it to provide molex power, and outside of thing being predictably slow, everything seems to be working. Even my floppy drive is working mostly fine, but that's kind of a moot point right now since it is the only real floppy drive I have, leaving me unable to make disks for doing stuff like reinstalling the system.

 
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