Found a 1980s service manual that explained a weird capacitor failure pattern I kept seeing

I was cleaning out my dad's garage in Toledo and found an old Zenith TV manual from 1985, and it had a whole section on how the glue they used on certain filter caps would become acidic over a decade and eat through the leads. I've probably replaced a dozen of those exact caps in old gear, always blaming age, not the factory process. Has anyone else run into this with other brands from that era?

3 comments

3 Comments

gavin_allen4812d ago

That bit about the glue turning acidic is wild. I had a similar shock with some old Pioneer amps from the late 70s. The foam they used to pad the circuit boards would just rot into this sticky black goop that ate right through component legs and traces. You'd open it up expecting to see a blown fuse and instead find this corrosive mess. It's crazy how a simple material choice can cause so many failures years down the line. What did the manual say to use for a replacement glue?

lane.drew12d agoMost Upvoted

But that foam probably saved a ton of units from vibration damage back then.

rose_young4d ago

Oh, the manual was probably like "use any standard adhesive," which is the engineering version of "good luck with that." So you're left trying to find a glue that won't turn into acid in 40 years but also won't melt the plastic case today. It's a real trust exercise with chemistry. You just have to hope the stuff you pick doesn't become the next forum horror story in 2050.