@ThePhoton 123 timer?

morning

I did study an RF book once ;o)

even passed an exam on it.

Won't call myself an RF engineer though

hi

no one online?

@raforanz nope

@jippie I know I had a comments discussion with someone once about whether a '123 could reliably make a pulse on the order of minutes...Just can't find that question anymore.

@ThePhoton probably evil mod cleanup job

Anybody ever hear of self-healing behavior in a ceramic capacitor?

@ThePhoton yes

@EwokNightmares OK?

I have heard to bake them for a while to "anneal" any piezo stresses

i guess that is not self healing but it fixes them when they are noisy

@EwokNightmares That can cure a short-circuit fault, or just eliminates any piezo-generated offset voltages?

you mean over votlage self healing?

@ThePhoton yes piezo generated noises

from mechanical or temperature stress during operation

@EwokNightmares I have a case where I am seeing a dc signal passed through a capacitor, and then after probing at it with a DMM, it starts working normally.

@ThePhoton what capacitor?

These guys:

atceramics.com/series.aspx?sid=40&series=550L-Series

"is ideal for D.C. Blocking"

:D

@EwokNightmares Which is exactly what I'm trying to use it for.

ok but I suppose the setup would help troubleshoot that problem since nothing inherent shows up about that cap

the probing it would seem to be a discharge effect

passing DC through could maybe depend on the output impedance of your DC regulator maybe?

not sure that is strange to me

when you probe it with a dmm what are you checking? capacitoance, voltage, resistance?

@EwokNightmares voltage. It also tends to inject a bunch of noise into the signal path (this is at the output of an RF amplifier) which might affect things. But after the circuit starts working it keeps working after I take the probes away.

I know self healing capacitors exist, don't know what type they are though.

probably MKT or so

@jippie Yes, when I google "capacitor self-healing", it's all about metallized film capacitors.

film != ceramic, is that what you're getting at?

@ThePhoton do you have schematic?

The amplifier U1 get's it's power supply current through the rf output port.

@ThePhoton don't see why dc would ever pass ..

@EwokNightmares Yeah, the capacitor has to be faulty. Another way is it could be an ac signal but because I'm looking at it with the 'scope set to 5 ns/div I'm only seeing a piece of the waveform that happens to stay out-of-range across the whole screen.

@ThePhoton did you just try replacing the cap?

@EwokNightmares Not yet

@ThePhoton -__-

are they rare? :P

@EwokNightmares $5 each. Not that rare but not jelly beans either

Also after I replace the capacitor I might make it even harder to reproduce the fault for further study.

@ThePhoton true, you think it is some shunting inside?

@EwokNightmares I think I am just nuts, actually.

@ThePhoton yes you might not gain much knowledge

thats work for people with microscopes

@EwokNightmares I could encapsulate it and cross-section it, for giggles. But that's a pretty tedious job. Also not sure if I know enough to cross-section it without creating new defects.

@ThePhoton i'd email the manufacturer before I went that far :P

@EwokNightmares Just got off the phone with their FAE actually

@ThePhoton did he have anything useful to say?

@EwokNightmares "If you hand-solder the parts, don't touch them with the soldering iron"...So now I have to contact the assembly shop and see if they did any hand-soldering on these parts.

it is 0402 right?

@EwokNightmares yes

that might explain a lot of my problems ever . . i always have deformed burned up caps

i think this guy may be from the future and asking questions about a computer that has not been invented yet electronics.stackexchange.com/questions/107546/…

@EwokNightmares Try washing with alcohol. A lot of times a film of scorched flux makes it look like you scorched your part.

@ThePhoton ya flux kills me too

i use too much flux and then it mixes with the burn parts and makes sparks and lightning shoot across all the parts