your eyes can trump an ESR meter
- Thread starter emrr
- Start date
Help Support GroupDIY Audio Forum:
TL;DR: "Look for the bulge."
It would be nice to know exactly what such caps looked like when brand new, but regardless, a top that's even slightly rounded vs. absolutely flat is at best suspect, and worthy of being replaced. A rounded-top cap should be considered "out of spec."
"This amp also had a shorted bridge rectifier..." This suggests that AC voltage straight from the transformer may have been put across the caps, surely causing damage and pulling excess current resulting in "several OPEN fuses" that surely blew before these caps REALLY heated up and exploded.
It would be nice to know exactly what such caps looked like when brand new, but regardless, a top that's even slightly rounded vs. absolutely flat is at best suspect, and worthy of being replaced. A rounded-top cap should be considered "out of spec."
"This amp also had a shorted bridge rectifier..." This suggests that AC voltage straight from the transformer may have been put across the caps, surely causing damage and pulling excess current resulting in "several OPEN fuses" that surely blew before these caps REALLY heated up and exploded.
Seeker
Well-known member
I've fixed a few amps and tvs using my eyes and nose. 25v caps don't last too long on 25v rails... To me, bad caps have a kinda fishy smell....
Yup shorted diode bridges can be cap killers....benb said:
[edit] most will leak electrolyte out the bung because they are designed to. I blew up a film cap once and it made a loud report, and rained tinsel all over my bench. [/edit]
JR
mike-wsm
Member
Those caps have a fail safe weak spot scribed onto the top - we had some biggies with blow-off valve underneath. Our drawing office mounted them direct on a pcb with no hole for the valve to blow through. We were cordially invited to the production facility where the manager showed us the holes made in the roof when the caps went ballistic. No humans were injured during the process, thankfully.
