Battery

[Shodan486]

HI! All

Should I be worried of the CMOS battery installed in a mobo while measuring ESR? Can something be damaged?

[ratdude747]

Re: Battery

you should be testing them out of circuit... just to be safe.

[Shodan486]

Re: Battery

you should be testing them out of circuit... just to be safe.

But when that's not possible?, i.e. DALLAS chip soldered directly to board ?

[stj]

Re: Battery

those modules only leak current on a couple of data lines that wont have caps on them - dont worry.

[Shodan486]

Re: Battery

you should be testing them out of circuit... just to be safe.

I hope I made my self clear when I said ''while testing ESR'' OF CAPACITORS on the mobo, not the battery itself

[stj]

Re: Battery

he means to be safe with the readings.
you cant trust testing caps on the mobo because you will be metering the stuff the cap connects to.
like more caps!!!

[Shodan486]

Re: Battery

he means to be safe with the readings.
you cant trust testing caps on the mobo because you will be metering the stuff the cap connects to.
like more caps!!!

Guys!

I really don't mean SAFE WITH READINGS...I mean if I can damage anything just by connecting the wires to the pads and activating my ESR meter. Don't care about the readings, just the current going thru the circuitry...so can be damaged something ?

[Shodan486]

Re: Battery

I just tested ESR on all caps on a VP6 I got from my neighbour he found in TRASH(!!!) but left the CMOS battery in the socket while testing the caps, all of the electrolytic ones over the board - thus can I damage some parts on the mobo?

[PCBONEZ]

Re: Battery

Safer to remove CMOS battery when possible but probably won't damage anything if you don't.
Handling and static are more likely to zap the BIOS chip than the meter as long as you are sticking the probes where they, um, should be stuck...

As someone tried to say,
you can't check VRM caps in the board because of parallel paths.

.

[Shodan486]

Re: Battery

And what happens if I use an ESR meter (particularly PEAK) for example measuring a crystal or a coil, MOSFET, just DOING dumb stuff - can be the board, particular part or the meter damaged this way? or ALL of them?

or for example just connecting the pads to a CMOS battery socket tips?

[PCBONEZ]

Re: Battery

All an ESR meter is is an ohm meter but instead of a small DC volts it uses a small AC volts [usually a square wave].

As long as the equipment is de-energized you aren't going to hurt the meter because the meter is where the voltage comes from.

The voltage is tiny.
The only component you might hurt is one that would be hurt by static.

.

[Shodan486]

Re: Battery

All an ESR meter is is an ohm meter but instead of a small DC volts it uses a small AC volts [usually a square wave].

As long as the equipment is de-energized you aren't going to hurt the meter because the meter is where the voltage comes from.

The voltage is tiny.
The only component you might hurt is one that would be hurt by static.

.

Alright, but let's see - the only energized part in the whole system when unplugged from the PSU is the connection from CMOS battery to the BIOS chip...can something be damaged when putting a for example voltmeter somewhere to this path, again, doing dumb stuff...imagine a little kid playing with an ESR meter just putting the probes wherever his young heart desires...just imagine this dumb situation - HOW can I damage a motherboard with such instruments - is it even possible? And when you guys measure the ESR of some caps, do you extract the CMOS battery from the board?

[stj]

Re: Battery

to be safe, remove the cmos battery - best to fit a new one after anyway.
and far more important, short the caps out with a screwdriver before you meter them.
or you may find one charged with 12v in it!

[Shodan486]

Re: Battery

to be safe, remove the cmos battery - best to fit a new one after anyway.
and far more important, short the caps out with a screwdriver before you meter them.
or you may find one charged with 12v in it!

not with my meter, able to discharge...but again, how can I damage a mobo with these tools?

[PCBONEZ]

Re: Battery

How many different ways are you going to ask the same question?

HOW can I damage a motherboard with such instruments.

You can't unless you beat the motherboard with the instrument.
You would damage it with static from your hands first.
- Mobo caps have discharge paths. They don't stay charged.

ESR of some caps, do you extract the CMOS battery from the board?

Yes.
Probably not necessary but I and I think most people do.
.

[Shodan486]

Re: Battery

many times if necessary, PCBONEZ ....

Okay, i think i made my point out...just asking sometimes crappy stuff, but it interests me so much..any other possible destructive ways, guyz?

[stj]

Re: Battery

the most motherboards i see damaged are from the screwdriver slipping as they are removed or the heatsinks unclipped!

[Shodan486]

Re: Battery

got a bit astray question : what are the rated voltages of those little MLCC caps? From what values do they range? And the capacitance? I've browsed a lot and found some from 50v to 100v, sometimes the capacitance was not provided.

[PCBONEZ]

Re: Battery

got a bit astray question : what are the rated voltages of those little MLCC caps? From what values do they range? And the capacitance? I've browsed a lot and found some from 50v to 100v, sometimes the capacitance was not provided.

http://www.mouser.com/Passive-Compon...ded/_/N-4gzxj/
http://www.mouser.com/Passive-Compon...-SMT/_/N-b2cj/