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Weird set of SE/30 issues - fast chimes/no sound otherwise


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So I'm repairing another forum member's SE/30 motherboard. Previously it didn't chime at all and would stay stuck on a grey screen.

 

After the recap, it works - somewhat.

 

It always chimes (boot/death chime) at a very fast rate - probably like 2x-3x the normal speed. Sometimes, it death chimes at a grey screen, other times I've gotten it to boot off an HD (it sometimes hangs on the Welcome to Macintosh screen - the HD is known good). No other sounds work. 

 

I've read up on other death chime issues with the SE/30 but I'm not sure what the fast chimes could mean, or why only these chimes are the only functional sound.

 

I've reseated the socketed ROM chips and swapped out ROM/RAM with known good ones.

 

Thanks so much!

 

-J

Edited by JRL
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I think I experienced something similar before. Are the chimes also pitched up?

Can't remember what the exact solution was, but I'd start poking around the ASC and check if all data and address lines are connected.

Usually the machine might also crash when it performs a read from the ASC and one of those signals is not connected.

 

Also check if Y3 actually outputs a strong and healthy signal. I had a board where the crystal had been damaged by cap goo and only output a very faint signal which resulted in dodgy sound.

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8 hours ago, Bolle said:

I think I experienced something similar before. Are the chimes also pitched up?

Can't remember what the exact solution was, but I'd start poking around the ASC and check if all data and address lines are connected.

Usually the machine might also crash when it performs a read from the ASC and one of those signals is not connected.

 

Also check if Y3 actually outputs a strong and healthy signal. I had a board where the crystal had been damaged by cap goo and only output a very faint signal which resulted in dodgy sound.

Yeah, they're also pitched up. Occasionally the chimes also glitch out completely (random tones)

 

I forgot to mention, when booting from my test HD the board would sometimes bomb due to lack of available memory to load any given extension or system file (seemingly random)

 

I'll have to check the lines later, thanks @Bolle

Edited by JRL
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10 hours ago, MrFahrenheit said:

What caps did you use to recap it with ?

AVX tantalums and Nichicon axials (the same ones I’ve done all of my personal boards with). I ESR tested every cap and all joints were redone to be sure.

Edited by JRL
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14 hours ago, JRL said:

AVX tantalums and Nichicon axials (the same ones I’ve done all of my personal boards with). I ESR tested every cap and all joints were redone to be sure.

The reason I ask is because I've had issues with using caps that are 'out-of-spec' so to speak.  The suggestion is that you can use higher voltage caps and it's no problem, however I've encountered problems doing that.  I recapped a Q610 with 20 or 25v (can't remember) 47uf caps, instead of 16v, and SCSI wasn't working, the startup chime was a bit weird, and flashing question mark took literally 5 seconds to blink each time, instead of just 1-2 seconds.  All caps were 'good'. I removed them all and replaced with 47uf 16v, ones that I have hundreds of for other Macs, and the same Mac was perfectly fine.

 

The other difference was the resistance of the caps.

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