Another dumb question..

[orange418]

Well Im not sure I remember all my electrical theory.. I know the basics like in parallel the resistance is less than the least and all that but I was measuring voltage the other day tracing back from my trim pot thinking I was suppose to get something like 5VDC.. One side of the trim pot to the other I get .4VDC.. On the other side of the cap attached to it I get .99vdc.   I continue that following the line and I get to the IC  getting 4.5 VDC, This side is connected to a tantalum...So in other words I'm getting .99VDC until I go on the other side of it where I get 4.5VDC...My question is does the mean my tantalum is bad? Do they ever go bad? I have never had that problem ever... Thanks... I'm sure without a schematic on hand this makes it difficult...

[Ronsonic]

Yes, good tants can go bad and in some very interesting failure modes.

It's a little hard to tell exactly what we're looking at from your description, but if you're looking at a part of the circuit that shouldn't have any voltage (and it isn't just floating up because there isn't a resistor to ground on it) then a coupling / blocking cap would be among your first suspects.

Capacitors have made a place for themselves very high on the failure mode charts. You are more likely to find a bad cap than pretty much any other electronic component. Electrolytics are the only common component with a serious shelf life issue.

Caps are always suspect.

Ron

[Steben]

Yes, good tants can go bad and in some very interesting failure modes.

It's a little hard to tell exactly what we're looking at from your description, but if you're looking at a part of the circuit that shouldn't have any voltage (and it isn't just floating up because there isn't a resistor to ground on it) then a coupling / blocking cap would be among your first suspects.

Capacitors have made a place for themselves very high on the failure mode charts. You are more likely to find a bad cap than pretty much any other electronic component. Electrolytics are the only common component with a serious shelf life issue.

Caps are always suspect.

Ron

I agree. It is common to spend hours debugging a circuit and find out it was a bad coupling cap that was blocking rather than coupling.