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

[JRL]

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

 

[Bolle]

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.

 

[JRL]

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

 

[MrFahrenheit]

What caps did you use to recap it with ?

 

[JRL]

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.

 

[MrFahrenheit]

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.

 

[JRL]

Ah I see. Yeah I can confirm that these caps are all the exact same voltage as the originals.

 

[feeef]

I revive this thread as I have a similar issue. I recapped an SE/30 that had the Simasimac screen pattern symptom. I only changed the surface mount caps and also used caps of the same values as the original.

When powering on, I can now here a pitched up startup sound and the mac stays on the grey screen as it would usually display before showing the happy mac (no more weired pattern).

JRL, have you found a solution yet? Or is there more info about what can cause this issue?

Thank you!

 

[feeef]

Here is a picture of the area around the ASC. I am unable to see what can be wrong. I tested each pins and tested for any short between pins and there was none.

I tried to do more cleaning of the area with some 95% alcohol. Then, the sound of the chime was getting worse. After trying to power on and off the Mac a few times, there is no chime anymore. Did I burn a component? Is alcohol conductive? I made sure that the board was visually dried before testing but some may have gone under the components?

 

[feeef]

One more update : After waiting a bit and doing a cold boot, the ugly chime is back again so I don't think I broke anything with my cleaning.

After inspecting the board again, I feel that instead of alcohol, it would be some flux that went under that ASC chip when I was soldering C7. Would this affect the behavior of the component?