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Discussion in 'Apple Collectors' started by iMacC2D, Nov 10, 2013.
You did a dang good job cleaning this up, handled like a master repairman! Blown caps seem to be a high cause of failure in older electronics, unfortunately.
As for the modification in the computer, isn't the 558 chip a quad timer chip? Don't know why it would've been replaced/modified but this was the age of CMOS and finicky-ness. Perhaps one stopped working a while ago, or it was the equivalent of a "green wire" fix? Either way it's an odd addition.
On a side note, what soldering iron(s) do you have? I'm about to upgrade and am looking for good reviews from real people who have more experience than I do.
Excellent post and a great write-up.
The two clips are most likely a keyboard shift-key mod. It uses the game port button to emulate (via software) an upper case key stroke. Usually used on 80 column cards. Normally done as a single wire mod, I can't remember why the addition of the second wire, unless it's actually for left & right shift keys.
Ahh... looking at the old keyboard encoder board pinouts, pin 3 (the red clip in your pic) is the CTRL key, and pin 24 (the black clip) is the SHIFT key.
I'm not sure what programs/OS took advantage of this mod, but most were word-processors and more advanced OS' like CPM (requiring a Z80 CPU Card and 80 Column Card). Many of the 80 Column cards for Apple II (NOT APPLE IIe) came with this mod kit.
EDIT: also, just a tip - if the PSU shuts down when more load is added (additional drives, more cards) replace the cap circled in red below.
Great work, great thread. This was a very enjoyable read.
Great informative repair guide.
Makes me proud to see that we Irish used to be able to manufacture computers that could last 35 years!
Very useful. The exact same component in my IIe PSU has just popped , you're right, the smell is horrendous.
Going to be taking it to pieces tomorrow and begin de soldering that component. Hopefully I can find a replacement easily.
Very nicely done!
What would happen if...
you didn't replace them?
mine poped too but was just curious what would happen...
Aye, any time you see the 'magic smoke', it's a capacitor. I recall working alsongside Brandon, an associate years back, repairing CBM systems. He was shocked when a cap blew in his face, and bluish grey smoke poured out; and from then on, he blamed 'the magic smoke that makes systems run, escaping', as the source of the failure.
I liked, and adopted the expression.
For soldering tools, Hakko, and Weller are my choice: I had a brill Weller SMD station back in the 1990s, and I loved it to death. Even the inexpensive Weller, and Hakko tools are of reasonable quality. Some outfitters sell one or the other with a very-fine end, and the other brand with a normal to fine end, for between £10 and £20.
My tip: Buy a basic thermal station, with an analogue thermostat/rheostat, and ignore whatever tool comes with it. Then, buy a decent Weller, or Hakko pencil, and use it through the station: The thermal stations aren't all that different by brand, unless you want digital controls. In that case, buy a station from Weller, with hot air, and suction.
Regarding component-level repairs: That used to be required to become an authorised Apple serviceman. After the SE-era, Apple changed to the 'replace the mainboard' policy, but repairs used to be done on-site. I retainted this philosophy through to 2006, which is when I stopped doing Apple service, as I didn't want to deal with Intel systems, for component level repair was next-to-impossible on them.
Everything by then was a BGA, which is not a fun component to reflow.
In the height of the Apple II era, while it wasn't an Apple II .. it was actually an Atari Time 2000 pinball game. It was outside a friends house, he'd just gotten it and it was acting funny, which was typically normal for Atari pinball machines.
On a pinball machine, the glass slides out the front and the play field raises up like the hood on a car, and you prop it with a stick.
Typically of the era, there were large power supplies in the bottom, and electronics in the head unit.
So I'm leaning in from the side trying to get readings on a lantern battery sized capacitor and a nearby bridge rectifier. The thing was dimming and coming back on a bit more rapidly than it should be and occasionally resetting the CPU.
I was in the wrong place .. at the right time ;-)
Another of those giant sized capacitors just blew it's top off. In this case, these things are mounted with the terminals facing up, and have screw posts rather than leads like PCB mounted units.
I kinda reacted just in time because as I was standing there I started to hear a hissing sound and then turned to see smoke starting to come from around the edge of a screw terminal before it went off. In the instant that I moved up and back, it went off and my head hit the play field as I was backing out, all I remember was a really low frequency reverberating pop, and white everywhere. As I went backwards and nearly tripped over stuff, after I'm about 15 feet away I can see surroundings again. The play field had slammed down and the whoosh created a gap in the smoke column and it had the appearance of a mushroom cloud. As I realized what had happened I screamed "holy ... " you can guess the other two words.
Then it started raining bits of white fine paper stuff, only slightly sticky.
I screamed 'nuclear winter!' and.. and his younger sister came out of the house, oblivious to all the smoke, barking dogs, and 'snowing paper crud' .. "Next time use less expressive language!" ..
Yup. Capacitors, have an amazing capacity. ;-)