SE/30 distorted or no sound

[CharlieFrown]

Hi, 

I am trying to revive my old SE/30 after capacitor goo disaster, which took its graphics and sound. It was cleaned and recapped. 

Had to replace UE8 and the display was brought back, now I want to do something with a sound. Initially it used to give me a startup sound, then the sound became distorted or non existing. Sometimes it booted with sound, other times booted with weird noise. 

Decided to clean up ASC (sound chip), solder it back, there's good connection between ASC and GLUE (tested both vias with multimeter), but I cant get the sound fixed. Now it's totally distorted, I can hear a random cracking noise just like old vinyl records. 

What's weirder when I try to open Sound control panel it freezes, while DiscCopy gives me a bomb as soon as alert sound begins (while inserting blank floppy). Bad sound caps or something else?  I think one of my capacitors (C4) in the sound section is not aligned properly, but it has a contact with a pad. 

 

[bibilit]

Capacitor C6 can be faulty as well.

Also Sony Chips UB10 and UB11 can be faulty or contaminated by capacitor goo.

 

[bobo68]

I'd check all connections of the ASC based on SE/30 schematics.

What kind of bomb / message do you get? I would assume that there is something wrong with the bus address lines incl. chips select etc. of the ASC.

HTH, bobo68

 

[ktkm]

Decided to clean up ASC (sound chip), solder it back, there's good connection between ASC and GLUE (tested both vias with multimeter), but I cant get the sound fixed. Now it's totally distorted, I can hear a random cracking noise just like old vinyl records. 

What's weirder when I try to open Sound control panel it freezes, while DiscCopy gives me a bomb as soon as alert sound begins (while inserting blank floppy). Bad sound caps or something else?  I think one of my capacitors (C4) in the sound section is not aligned properly, but it has a contact with a pad. 

I experienced something similar yesterday with an SE/30 I saved a couple of weeks ago. All the chip capacitors had leaked resulting in a horrible sound, allmost like an old modem and every time I opened the sound preferences resulted in bus error. I cleaned the entire board with hot water, dishwashing liquid and tooth brush. Looks, feels and sound like brand new! But for how long? Re-cap next step …

/ktkm

 

[nvdeynde]

Have a look at C4. Does it make proper contact to the pads on the logic board ?

When I look at the photo, the position of the capacitor looks like it has turned a bit counter clockwise. You can see that the negative marking on the C4 capacitor in not 100% aligned properly.
I would re-test all the replaced capacitors for proper contact with the pads on the logic board and verify they don't short anything close as well + ESR test them too. 

Have you replaced the 2 large axial caps as well of 220 and 470uf ?

Do you hear the same noise as well through the headphones socket ?

 

[CharlieFrown]

thank you guys for suggestions, will try to focus on these 4 caps esp. C4 and C6. 

Havent replaced large axial caps yet (should I?).. just all the SMD caps. 

 

[Johnnya101]

Yes, replace all the caps!