Mac Plus: Restoration

[LC_575]

Thanks to some tools borrowed from my friend, I finally managed to get the case open on my Plus (never again will I ever screw in those handle screws!).

Like any 25 year old computer, the Plus has suffered some damage. The case body has some substantial rust stains that my friend described as acid stains - they're white deposits. They're mainly concentrated on the case body (specifically around the logic board tray) and have damaged the power board (around the mains power connector) somewhat.

On the brighter side, the logic board appears to have been completely spared from any sort of rust damage, or even cap damage. The power board, outside of that one damaged area, looks fine too; even the caps aren't bulging.

Anyways, when I turn it on I get a distorted bong and then a black screen covered in white rasters and a Sad Mac in the dead center - screen is too garbled to get an error code.

What do I do next?

 

[LC_575]

Okay, I successfully disassembled the plus. I believe I discharged it properly, touching the anode clips and aperture to the ground lug (via screwdriver + alligator clip wire), but I didn't hear the charcteristic "pop" sound. Just to be sure, I also discharged the clips and aperture separately afterwards.

Anyways, here are some pics of the Plus:

Logic Board:

Power/Sweep Board:

What's next?

 

[techknight]

dont see anything.

 

[LC_575]

Did you miss the large corrosion stain on the power board in the last three pics?

 

[techknight]

what pics. there are no pics.

 

[Concorde1993]

what pics. there are no pics.

Same here, LC_575. Try uploading them again.

 

[Apostrophe]

Check the thread I started myself on displaying pics in posts:

viewtopic.php?f=1&t=11095&start=0&hilit=

-Apostrophe

 

[LC_575]

This is very odd....

I'll try reuploading them.

 

[LC_575]

OK, here they are:

Logic Board:



Power/Sweep Board:

 

[Mac128]

I'm not really seeing any obvious problems here. If you're talking about the corrosion on the bottom lower corner of the PSU, then that's a non-starter. Strictly a grounding point. Should not affect operation in the manner you describe.

You are best to go through Dr. Tom Lee's excellent tutorial for testing, checking, and repairing to see if any of the usual problems crop up first.

 

[LC_575]

And where will I find that?

 

[LC_575]

Can any Plus experts help me out with this?

 

[Mac128]

Patience young Jedi.

I am still surprised why this link is some kind of treasured Eater Egg in this site. Other than having been posted literally dozens of times in related threads (which I assume you did not search), I know of no way to find this otherwise.

http://68kmla.org/files/

I am further surprised nobody else beat me to it. Very telling indeed.

 

[LC_575]

Sorry 'bout that. My first instinct is to do a Google search, which was fruitless.

Anyways, I'll take a look and get started. Watch here for updates.

 

[gubbish]

I had a very similar symptom in a Mac Plus. Distorted bong, video strangeness, sad mac with strange pixels. It turned out that it was bad RAM - two of the SIMMs in that Mac turned out to be bad. Replaced them and it worked fine. Might not be the same problem with yours, but it's easy to test at least.

 

[Trash80toHP_Mini]

I am still surprised why this link is some kind of treasured Eater Egg in this site.

Me too, but I don't hang out here in the Compacts Forum very much! :-/

That'd be a great one to add to the Peripherals: LINKS Project: Rev. 3.0 along with any others you might know about!

p.s. It never was just about peripherals, I was assigned as the new mod of that particular forum when "the kids" promoted me back in the day.

p.p.s. Hey, maniac, where are you?!?!?!

 

[mcdermd]

Distorted bong, video strangeness, sad mac with strange pixels. It turned out that it was bad RAM - two of the SIMMs in that Mac turned out to be bad.

I had the same in a 128k. It was a bad RAM chip too. I soldered a new one in and it was fine again.

 

[LC_575]

One technical question: Once disconnected, is the Anode wire and it's flyback transformer still dangerous to touch? Should I discharge it again (power/sweep board has been sitting for a few days now)?

 

[Dog Cow]

One technical question: Once disconnected, is the Anode wire and it's flyback transformer still dangerous to touch? Should I discharge it again (power/sweep board has been sitting for a few days now)?

Sure, and I even discovered a fun/novel way to discharge it while working on a small b&w set the other day:
take a small, damp rag/washcloth, held in one hand, and dangle it around the anode wire where it enters the tube (on this CRT, it was bare; didn't have a rubber thingy covering it). It will make a nice spark, and you'll feel your heart beat faster for a bit. Fun.