Macintosh Classic No Audio

[Otho]

Hello folks! I'm working on bringing my college 1991 Macintosh Classic back to life. It suffered from leaking capacitors and was completely dead, so I decided to learn how to solder and did a complete recap of both the logic and analog boards and a through cleaning with 99% iso. After some reflowing of my amateurish soldering it came back to life in all regards except one - a complete lack of audio. At this point I am stuck. I have checked the speaker (resistance 61.5 ohms), tried using headphones (no sound), and desoldered, cleaned, and resoldered the UA5 sound chip twice. I cannot see any broken traces - is the sound chip simply dead? I am new to this, so any advice would be most welcome! I am attaching some photos of the logic board as it currently sits.

Many thanks!

Otho

 

[bibilit]

Probably a broken trace, use a multimeter and check continuity from the chip and to any capacitor

 

[imactheknife]

You might in a worse case scenario have to remove sound chip and clean pads/legs and repair traces. Check top of legs to the pads on sound chip and then legs / pads to vias / caps. Sometimes its best to check these before new caps are put on as the broken trace can be right underneath due to cap leakage.

Good job by the way always fun to try and fix up and old mac

 

[Otho]

Probably a broken trace, use a multimeter and check continuity from the chip and to any capacitor

Will do! Haven’t found any broken traces yet, but I will stick to it- thanks!

 

[Otho]

You might in a worse case scenario have to remove sound chip and clean pads/legs and repair traces. Check top of legs to the pads on sound chip and then legs / pads to vias / caps. Sometimes its best to check these before new caps are put on as the broken trace can be right underneath due to cap leakage.

Good job by the way always fun to try and fix up and old mac

Agreed, and will do! I haven’t found any broken traces yet, but I will stick to it. I’m focusing on the C3 cap and UA5 chip just as you suggest. Many thanks - been a real trip bringing this back to life and reading through 30+ year old files on it.