Is this electrolyte leakage?

[gblades]

I have removed one cap from this power supply as it was bulging top and bottom so oviously faulty.
Are the brown marks you can see here elecyrolyte leakage or glue?
Some of the connecting plugs do have a thin layer of a brown rubber type compound on them which is oviously designed to stop them coming off by themselves but I dont know if the marks on the board are the same stuff. You can see a large clump of stuff between the cap and inductor on the 1st picture.

[acstech]

Re: Is this electrolyte leakage?

Looks like electrolyte to me. I don't think glue would flow like it looks like that stuff did. I say replace those buggers. Clean off the board good when they're out though.

[kc8adu]

Re: Is this electrolyte leakage?

its glue.
definately clean it off as it can corrode stuff.

[gblades]

Re: Is this electrolyte leakage?

Thanks. I am looking to get an ESR/Capacitance meter next week so will probably test all the capacitors anyway as others could well be bad but not showing any physical signs.

Its a cheap dvd recorder. Aparently it started going wrong where it would power on but when trying to eject the DVD it would power itself off. However after getting it home it does not power on at all.

First step is to get it to a state where all the caps are ok on the psu and then go on from there.

[kc8adu]

Re: Is this electrolyte leakage?

only sure way is replace all known crapcaps esp on the secondary.

[Krankshaft]

Re: Is this electrolyte leakage?

Even with an ESR meter its important to measure suspect caps out of circuit. Especially on the secondary.

You may get a normal to borderline bad ESR reading in circuit and a large reading out of circuit. I remember yesterday on an another Antec TP 2.0 500W I bought which was supposed to be in working condition.

Thanks e-bay the thing couldn't even sustain itself when I turned the compouter on it cycled on and off. The power light looked like a strobe light. I intended to recap it immediately but I at least expected it to work out of the box .

Anyhow the 12 volt rail cap measured something like 8.5 in circuit and when I took it out it measured 47 ohms . It was visibily bad however some caps blow out their bungs leaving their tops intact.

The cap was in so bad of a shape that it couldn't hold the charge from the 12 volt rail. A switching transformer only passes the energy from the primary to the secondary while the switching transistor is off.

So in addition to filtering out the AC ripple the capacitors job is also to supply the energy needed during this dry period when the switching transistor is off until it comes back on.

This explains why the computer was cycling on and off the cap was getting drained faster then the supply could charge it.

By the way the two 1000uf 10V standbys were over 99 ohms so the meter read a - .

So always make sure that you test ANY suspect caps out of circuit by either removing them or desoldering one of their legs.

Also the ESR meter isn't the holy grail of cap testing there is a rare condition where caps loose their capacitance with the ESR being ok. However this is a rare occurrence and doesn't happen too often.

[gblades]

Re: Is this electrolyte leakage?

Thanks for that info. As the primary was bad it makes sense that it could lead to the unit no longer turning on if in turn the secondarys could not function properly.

The ESR meter I am looking at does measure capacitance aswell so should be a very valuable tool.