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mst3k

Color Classic II mystic sound problems & no chime?

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Greetings,

I just purchased a Color Classic 2 with the mystic, LC 575, upgrade.

I'm interchanging two different boot disks, one with System 7.5.5 and one with System 8.0.

It was working fine until the sound suddenly stopped working.  I had installed a Farallon Ethernet card and it worked fine and everything was good for about 4 hours, then NO sounds.

I've checked all the obvious things: volume levels, control panels, zap PRAM, checked the speaker wire connection, etc with no luck.

The computer boots fine and runs fine but the speaker makes only a small 'click' where the boot chime noise should occur and NO noises after booting.

The volume controls on the front of the computer work properly, adjusting volume levels up and down (by observing the sound control panel) but no sounds.

I hooked up a set of headphones to check if the internal speaker was bad, but got the same result.  A soft 'click' on boot through the headphones and no sounds after that.

The motherboard was recapped and everything looks good.  I've checked all the new capacitors to make sure they are correctly installed (polarity) and have a solid connection.  All good.

Any ideas?  Is there a sound processor or something on the analog board that could fail to produce this problem?

Again, everything works fine, just NO sounds including NO startup chime sound.

Thanks in advance for your help!

 

 

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I can not help with your sound issue. But, as an aside, you can upgrade to 8.1 with out issue.  I believe it has been said that 8.1 is more stable than 8.0.

 

Wish I could help with the sound, but I just do not know enough. I hope someone can jump in here...  I am guessing that if you boot to a floppy you have no sound?  And is it true you have no sound when your boot your hard drive to 8.0 as well as 7.5.5?

 

mraroid

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Probably time to check the PLCC IC sound chip which is surrounded by four caps which have possibly leaked or taken out a trace nearby.  Check also the legs of the IC for any damage or lifting.

 

https://recapamac.com.au/macintosh-lc575/

 

See top left of board around the four capacitors, check this

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Thanks for the help and ideas.

The chip itself looks 'fine' and I see no evidence of lifting around the chip or the chips socket (which I assume is what you're referring to).  However, the board itself around the two replaced caps left of the sound chip look suspicious.

If the board itself is damaged, is there a cure?  Or is the only option a new board.

Thanks again!

 

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I think you found the problem mst3K.  And, if not your chime problem, it will be a problem in the future.  I suggest you fix it.

 

You can buy small insulated wire, and then solder a "bridge" between the two points on the board to make very sure you have a good connecting.  It might look a bit looks wonky, but if you know how to solder,  it will work as well or better as a trace and function just fine.

 

Enclosed is a photo of some wire I use.  Actually, I use a wire gauge that is slightly smaller then this wire, but I can not find my reel of wire right now in my messy basement.  The reel of the smaller gauge wire I prefer to use has the gauge written on it, but I can not recall it at the moment.  But I think you get the idea.  And I think wire the size in my photo will work just as well.

 

Keep us updated

 

mraroid

rsz_wireb.jpg

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You can take a strand out of some ethernet cable and use that. I've also used leftover wire from phone/ethernet punch down blocks as well.

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15 hours ago, mraroid said:

I think you found the problem mst3K.  And, if not your chime problem, it will be a problem in the future.  I suggest you fix it.

 

You can buy small insulated wire, and then solder a "bridge" between the two points on the board to make very sure you have a good connecting.  It might look a bit looks wonky, but if you know how to solder,  it will work as well or better as a trace and function just fine.

 

Enclosed is a photo of some wire I use.  Actually, I use a wire gauge that is slightly smaller then this wire, but I can not find my reel of wire right now in my messy basement.  The reel of the smaller gauge wire I prefer to use has the gauge written on it, but I can not recall it at the moment.  But I think you get the idea.  And I think wire the size in my photo will work just as well.

 

Keep us updated

 

mraroid

rsz_wireb.jpg

I have the same issue with a CC original board...will this work!

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