- The Mac IIsi has an intermittant internal speaker. Often it will play loud
sounds, but not soft ones.
- YOu can get around this by occasionally cranking up your speaker volume to
max, then turning it lower. The speaker will work for a while. There's a DA
to do this for you.
- Another workaround: use an external speaker, plugged into the rear panel
jack.
- Internally, the reason for the problem is corrosion on the connector
between the speaker and the PC board. Bill Trent points out that it's
Fretting corrosion, essentially oxidation of the contact points.
I've tried four things.
1) cleaning the contacts. This worked for about 3 weeks.
2) Contact cleaner/lubricant. This worked for a month or two.
3) Silver solder. Old Tektronix vacuum tube oscilloscopes have a small spool
of silver-solder inside of 'em. I used a bit of this on the PC board, right
where the contacts are made. The problem returned in about a month or so.
4) Replacement of the contacts with gold. I found a transistor with gold-plated leads -- a big power transistor with thick, stiff leads. I clipped off the
leads, then soldered them onto the PC board. I made sure that the leads were
soldered at the ends, but that the middle of each lead was exposed. This way,
the contacts rub against gold, not solder.
____________________
xxxx PC Board xxxxxx|
--------------------
--------------- <<< solder
\_________/ <<<< gold plated lead
( )
/ \
_/ \________________________ <<< contact for speaker
Solution #4 has solved my problem for the past few months. Your milage may
vary.
Cheers, Cliff Stoll
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