Friday, June 14, 2013

Macintosh LC Repair Part 3

With a list like the one I made in my last post, you would think that writing up an order would be simple. Well, it certainly could not have been more time consuming! Finding the value of capacitors I needed was simple enough with Mouser's filter at my disposal, but locating a cap of the perfect pin distance and a reasonable diameter by a reputable that takes time. The caps I chose are all from either Nichikon or Panasonic as recommended on the Bad-Caps forum. Luckily, each one of them was only a few cents more than a bad brand of caps, so no loss.

All of my parts arrived today, but first allow for me to supply links to the parts that I purchased:




You will notice that I ordered two connectors and hoods. This is what I will use to make the proprietary Apple Y-cable for connecting a floppy drive and joystick. I do not plan on supporting a floppy drive though as I will probably never get one, but I will need a joystick for games!

Anyhow, if I plan on putting these caps on the board then I have to remove the old first! My personal favorite devices of choice: one radioshack desoldering iron and chip quik solder. I have used the same desoldering iron for several years now and have only needed to replace the $1.99 tip a couple of times, it just depends on how rough you treat it.

Chip Quik solder on the other hand is a special 63/37 Tin/Lead solder which has an incredibly low melting point. This low melting point makes it ideal for removing surface mount components such as PLCC chips, SMT caps, soic chips and more; I sometimes use it on pesky through-hole parts. The solder will remain molten for nearly a minute after applying it, so the component can be plucked right off the board without damaging contacts. It also cleans nicely from the board when you need to use ordinary solder for putting chips back on your boards.

I could not have removed any of these components from the boards without these items. I started with the Power Supply which has all through-hole caps:

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The first picture is of the filthy board after removal. Several of the caps had leaked and left a thick goo behind. The second pic is after I cleaned the board and the last picture is of all of the caps. Notice that some have a crusty residue, but others do not. Even though some of them had not leaked, they are all the same age and it is in my best interest to replace all of them.

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I started removing components as you can see above and the finished removing them and then cleaned the board. This was the most corroded area on the board and I lost none of the pads! Even the LM3080 which looked irreparable may be useable after removing the corrosion.

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Last of all as the Apple IIe card. This turned out to be the most difficult because the components are much closer together and I certainly could remove the PDS connector! One cap lost a pad, so I will have to make a repair...but only one trace out of a hundred seems to be a success! The Third is a picture of everything I removed from the motherboard. Caps, IC's and even the through-hole audio jacks. I felt that I had to remove more than was afflicted to access all of the caps.

In my final part of these posts, I will populate the board with all of my new caps and the old IC's. With any luck, we will have a fully functioning Macintosh LC!

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