LC III - Strange Mod, What do you think?

[uniserver]

i just got this in the mail today, this is my first LC-III maybe these mods are normal?

[BGoins12]

Looks like a normal LCIII board to me. Identical to mine.

[uniserver]

you see the little green wires, soldered to the chips etc?

[BGoins12]

My bad vision got me again! I didn't even see those. Nope, mine doesn't have that at all.

[jruschme]

Probably not a mod, per se, but an early rev board that had engineering fixes applied at the factory.

[mcdermd]

I have a Classic II with the same sort of "corrective" wiring in blue.

[techknight]

looks clock chipped. overclocked to 33mhz.

[uniserver]

thanks, i did notice on the cpu it says 33mhz,

[Trash80toHP_Mini]

Those are almost certainly factory fresh patch wires for a defective PCB.

They ought to have caught anything like that mess at the prototyping stage . . . but you never know!

[uniserver]

Booted up TechTool® Pro and it says the cpu is clocked at 25mhz... by:System and by:TechTool

[Cory5412]

Just like JT said, in the olden days they used to test Macs and fix them before sending them out -- they probably do today too, but they would not fix it like this today, if for no other reason than most of the Macs that are shipped today are too small. (Also, timing issues probably caused by external wire fixes like this would throw a modern machine at >1GHz totally out of whack.)

But, although I haven't seen it on very many other machines, this isn't the first time Iv'e seen photos of an LC III done up like that.

[techknight]

I wonder if it was a bad section inside a chip that they compensated for ? maybe a bad PCB trace?

hard to say. But it is interesting nevertheless. Looks like a whole new IC put into place?

Now-a-days, they would just toss the entire board into the scrap bin and put in another. But thats if they run into the issue to begin with. Some factories only test 1 out of every group of 20 or more, especially with LCD TVs.

[olePigeon]

I like it. I think it adds character.

[Trash80toHP_Mini]

Back in the Neolithic, they used a pad <-> trace tester before populating the board for wave soldering. They fixed bad traces with patch wires with hot glue dots at every twist and turn of the surface and sub-surface trace to eliminate timing errors.

Minor PCB layout boo-boos were fixed in production by cutting the trace on the surface and then patching. They probably did the same when a pair of traces were shorted as well.

[techknight]

its rare, but i do see layout booboo repairs every once in awhile. Thing is, its hard to say if it was factory, or a tech repair/modification.

[James1095]

I have an SE/30 with the same thing, a few patch wires done with blue wire-wrap wire. I've seen it on other equipment of that era as well. Usually done from the factory. Occasionally you find more substantial modifications that were done either in the factory or through a recall to fix problems that showed up late in the game. It was cheaper to rework each board by hand than to start all over with new ones. Chips were fiendishly expensive in those days.

[uniserver]

yeah this machine has been running great,
It's been OC'd to 33mhz, Installed a FPU, Installed a heatsink on the cpu, however the VLSI chip needs a HS as well.