stevel@eleazar.dartmouth.edu (Steve Ligett) (01/27/89)
I was playing around with the ADB on a Mac II, and after a while, the keyboard and mouse no longer worked. I had blown the fuse on the motherboard that supplies power to the Desktop Bus. I took the Mac II downstairs to the shop, and asked, "How much does it cost to fix this?" "Oh, about $300", they said. The standard repair is to replace the motherboard. The fuse (F2, I recall), is a little PICO II fuse that is soldered to the board. I found them in my Digi-Key catalog for $3.23 for 5, part number F826-ND. It's a one amp fuse, though the hardware reference cautions against drawing more than 1/2 an amp from that port. A 1/2 amp fuse is part number F824-ND, and a 3/4 amp one is F825-ND. Even though the Mac II wasn't even mine, I repaired it by replacing the fuse. Shhh, don't tell, ok? I can't recommend that you do the same. Next time, I'll use an old Mac II that doesn't have an ADB fuse. Steve Ligett steve.ligett@dartmouth.edu or (decvax harvard linus true)!dartvax!steve.ligett
gillies@p.cs.uiuc.edu (01/29/89)
Why does Apple do this sort of stuff?
-- Why would anyone solder a fuse to a circuit board?
-- Why would anyone solder a battery to a circuit board?
Apple electrical engineering sure is wierd. I sure hope they don't
start soldering disk drives into their computers!
Don Gillies, Dept. of Computer Science, University of Illinois
1304 W. Springfield, Urbana, Ill 61801
ARPA: gillies@cs.uiuc.edu UUCP: {uunet,harvard}!uiucdcs!gilliescurry@garth.UUCP (Ray Curry) (02/01/89)
In article <76000341@p.cs.uiuc.edu> gillies@p.cs.uiuc.edu writes: > >Why does Apple do this sort of stuff? >-- Why would anyone solder a fuse to a circuit board? >-- Why would anyone solder a battery to a circuit board? It's amazing how simplistic a view of the world we have. Soldering in fuses has been going on since fuses were invented. You have them in your stereo, tv, and lots of other places. Some don't even look like fuses but are avalance type diodes designed to open on failure. The reason for it is to protect against really bizarre circumstance that normally won't happen. There is no significant load that should be present on the ADB bus and the fuse was probably added to protect circuitry in case of abuse. In such circumstances, where failure is 1 in a mil. or so, the reliability of the soldered in is better. Put it in a holder, you have 1 failure in 100,000. Solder it in and you have 1 in 1,000,000.
fiddler%concertina@Sun.COM (Steve Hix) (02/02/89)
In article <76000341@p.cs.uiuc.edu>, gillies@p.cs.uiuc.edu writes: > > Why does Apple do this sort of stuff? > > -- Why would anyone solder a fuse to a circuit board? Someone else covered this one recently... > -- Why would anyone solder a battery to a circuit board? If you have a low-drain application battery installed in a spot where it's expected to perform for a long time, the most common cause of failure is typically degradation of the batteries contacts. If you have a battery that is expected to provide a low current for a long time, the most common failure derives from oxidation of the contacts. If you expect that most of your customers aren't willing (or able) to hop inside and fix things (or figure out what the problem is, you just might try soldering the battery in place and sidestep the problem. Icky maybe, but it saves a lot of grief spread over a couple million systems. When one of my cameras is five years old, I have to send it back to the maker to replace the...um...prarmeter RAM battery. Might as well replace the LCD panel on the top at the same time, since it will probably have degraded quite a bit by the same time. Beats cleaning and lubricating gears periodically, I guess.
kaufman@polya.Stanford.EDU (Marc T. Kaufman) (02/02/89)
In article <87923@sun.uucp> fiddler%concertina@Sun.COM (Steve Hix) writes: >In article <76000341@p.cs.uiuc.edu>, gillies@p.cs.uiuc.edu writes: >> Why does Apple do this sort of stuff? >> -- Why would anyone solder a fuse to a circuit board? >> -- Why would anyone solder a battery to a circuit board? The REAL question, not yet answered, is why anyone would charge $300 to solder in a new fuse! It's not much of a repair organization that can only swap whole boards to replace a bad component. Marc Kaufman (kaufman@polya.stanford.edu)
shane@chablis.cc.umich.edu (Shane Looker) (02/02/89)
In article <6574@polya.Stanford.EDU> kaufman@polya.Stanford.EDU (Marc T. Kaufman) writes: >In article <87923@sun.uucp> fiddler%concertina@Sun.COM (Steve Hix) writes: >>In article <76000341@p.cs.uiuc.edu>, gillies@p.cs.uiuc.edu writes: > >>> Why does Apple do this sort of stuff? >>> -- Why would anyone solder a fuse to a circuit board? >>> -- Why would anyone solder a battery to a circuit board? >The REAL question, not yet answered, is why anyone would charge $300 to solder >in a new fuse! >It's not much of a repair organization that can only swap whole boards to >replace a bad component. Actually, this is another of Apple's bright ideas. Technicians are not allowed to fix anything on a Mac board. The only solution is to swap the logic board. If you change anything on the board, Apple will disavow any knowledge of the board, and you are on your own. I got this from the technicians downstairs who do Apple repairs for the campus. (They are certified by Apple). Shane Looker | Looker@um.cc.umich.edu | shane@chablis.cc.umich.edu
steph@maui.cs.ucla.edu (Stephen Sakamoto) (02/03/89)
>In article <87923@sun.uucp> fiddler%concertina@Sun.COM (Steve Hix) writes: >>In article <76000341@p.cs.uiuc.edu>, gillies@p.cs.uiuc.edu writes: >>> Why does Apple do this sort of stuff? >>> -- Why would anyone solder a fuse to a circuit board? >>> -- Why would anyone solder a battery to a circuit board? In article <6574@polya.Stanford.EDU> kaufman@polya.Stanford.EDU writes: >The REAL question, not yet answered, is why anyone would charge $300 to solder >in a new fuse! >It's not much of a repair organization that can only swap whole boards to >replace a bad component. Yes, but, it allows Apple to get field repairs done by people without a lot of technical knowledge. I have gone thru service certification and you would be amazed at who can pass. Actually its kind of scary. I have been rebuilding our LaserWriters and have 4 that are pushing 200,000 copies and one that is past 300,00 and humming along. Have done my fair share of Mac power supply repairs too. Shhh...Don't tell Apple. :-)) Stephen Sakamoto UCLA Computer Science Department steph@cs.ucla.edu
stevel@eleazar.dartmouth.edu (Steve Ligett) (02/06/89)
In article <6574@polya.Stanford.EDU] kaufman@polya.Stanford.EDU (Marc T. Kaufman) writes:
...
]The REAL question, not yet answered, is why anyone would charge $300 to solder
]in a new fuse!
]
]It's not much of a repair organization that can only swap whole boards to
-------------------
]replace a bad component.
]
]Marc Kaufman (kaufman@polya.stanford.edu)
Ah, that "repair organization" is called Apple Dealers. Dealers are not
supposed to solder anything. Swaps are the only standard repair. I
made a mistake in my first posting -- I did not replace the fuse, our
shop did. They warned me that such a repair wouldn't have an Apple
warranty, but I said that I trusted them to do it. The repair cost $9
(1/4 hour charge) (I supplied the fuse).
What bugs me is that the Apple way of doing things is to minimize cost
and risk to Apple with little if any thought for the customer. They
minimized the manufacturing cost by soldering in the fuse, and minimized
the risk of a dealer actually repairing a board by having it done as a
swap. They make more profit at both ends.
Steve Ligett steve.ligett@dartmouth.edu or
(decvax harvard linus true)!dartvax!steve.ligettgrg@berlin.acss.umn.edu (George Gonzalez) (02/07/89)
> ( much discussion about Apple not using fuse sockets, ... )
If you look back, there's a very strong reason Apple shies away from sockets.
Apple has not done very well with electrical connectors.
On the Apple II, my most common problem was disk errors. Cleaning the
card-edge connection fixed the problem every time. Seems that Apple used
tin or solder plating on the card-edge connector. The tin would corrode
and eventually fail to make good electrical contact.
Also on the disk II controller, the connector to the disk drive was not keyed.
It could be inserted in many orientations, most of them blew out something
in the drive or controller.
The II's chip sockets were also pretty flaky. Pushing down on the chips
was a well-known ritual whenever the II was acting up.
On the Apple III they had even greater problems with connectors. I believe
they had to replace every board in the field due to connector problems.
(Was it the RAM chip sockets, or the inter-board connector? I don't remember).
I don't recall any connector problems on the Lisa. They may have switched
to premium gold-plated connectors after the Apple III problems.
So Apple had quite a history of connector problems *before* the Mac.
Not too surprising that the original Mac had a minumum of electrical
connections: No sockets for any chips, except ROM's. Even so, they goofed
by using a very cheap, tin plated connector for the CRT yoke. This
connector failed on a lot of Mac's, giving the well known "vertical line".
So its not too surprising that Apple engineers soldered in the fuse.phssra@mathcs.emory.edu (Scott R. Anderson) (02/22/89)
In article <11984@dartvax.Dartmouth.EDU> stevel@eleazar.dartmouth.edu (Steve Ligett) writes: >I was playing around with the ADB on a Mac II, and after a while, the >keyboard and mouse no longer worked. I had blown the fuse on the >motherboard that supplies power to the Desktop Bus. I took the Mac II >downstairs to the shop, and asked, "How much does it cost to fix this?" >"Oh, about $300", they said. I recently lost the modem port on my Mac II; the port can receive, but it can't transmit. Of course, I got the same story from the repair techs. Anybody know a similarly simple fix? By the way, if it costs $300 to replace a Mac II logic board, why is an upgrade to a Mac IIx (consisting of a similarly simple board swap) seven times as much? * * ** Scott Robert Anderson gatech!emoryu1!phssra * * * ** phssra@unix.cc.emory.edu phssra@emoryu1.bitnet * * * * * ** * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *