Measuring switching frequency ?

[bianchi77]

Guys,

How can I measure the switching frequency of my ATX power supply ?
Is it just switch to Hz on my DMM ?

Thanks

[joshnz]

Re: Measuring switching frequency ?

yes just measure on secondary

[bianchi77]

Re: Measuring switching frequency ?

I got 312Hz is that right ? positive DMM to +12 psu and 0 to ground

[stj]

Re: Measuring switching frequency ?

you should meter before the diodes.
if your seeing that on the output cables then your capacitors arent up to the job!

[bianchi77]

Re: Measuring switching frequency ?

What's the common frequency used ?

[stj]

Re: Measuring switching frequency ?

there isnt one, look at the controller chip part number - the frequency will be in the datasheet
i suspect it's half what you metered

[bianchi77]

Re: Measuring switching frequency ?

the controller is 2003

[stj]

Re: Measuring switching frequency ?

well someone with more psu knowlege will have to give us the datasheet.

[CapLeaker]

Re: Measuring switching frequency ?

https://www.badcaps.net/forum/attach...2&d=1391622049
That's for the 2005.

[keeney123]

Re: Measuring switching frequency ?

I got 312Hz is that right ? positive DMM to +12 psu and 0 to ground

Are you sure that isn't 312 KHz

[CapLeaker]

Re: Measuring switching frequency ?

312 Hz would be waay to slow. I was hoping he forgot the (k)Hz.

[bianchi77]

Re: Measuring switching frequency ?

it's Hz in DMM....

[CapLeaker]

Re: Measuring switching frequency ?

that' s not right. look up the specs on your DMM. Maybe it can't measure that high.

[kaboom]

Re: Measuring switching frequency ?

that' s not right.

yes, it can be!


if the feedback compensation is off, the loop can oscillate at some low frequency- anything from a few hundred Hz to a few kHz

bet there's not any load either- some will oscillate w/o load

this is not switching freq bleeding thru

wanna measure switching freq? one lead to the chassis and the other to an outer lead of one of the common-cathode rectifiers

[CapLeaker]

Re: Measuring switching frequency ?

yes, it can be!


if the feedback compensation is off, the loop can oscillate at some low frequency- anything from a few hundred Hz to a few kHz

bet there's not any load either- some will oscillate w/o load

this is not switching freq bleeding thru

wanna measure switching freq? one lead to the chassis and the other to an outer lead of one of the common-cathode rectifiers

His measuring point is wrong. He went to the output of the 12V to GND. So he's measuring the ripple of the cap.

[kaboom]

Re: Measuring switching frequency ?

His measuring point is wrong. He went to the output of the 12V to GND. So he's measuring the ripple of the cap.

He's measuring the oscillating feedback loop! The hunting is that 312Hz.

"ripple of the cap" -what does that even mean?!

That 312Hz will change as the load on it changes, believe it or not...

[CapLeaker]

Re: Measuring switching frequency ?

Supposed to be on the cap. Autocorrect at its best again. Oh yeah, the switching frequency will change as the load changes, but 312hz is quite low for my liking. Time will tell.

[bianchi77]

Re: Measuring switching frequency ?

So negative side of DMM to chassis or earth n red one to +12

[budm]

Re: Measuring switching frequency ?

So negative side of DMM to chassis or earth n red one to +12

Not on the 12V, on the ANODE of the rectifier diode for the 12V which is the AC feed to the Anode of the rectifier. May be you should look up how rectifier is used and connected to an AC source to rectify an AC then you will understand where to put the probe to measure what you are looking for, need to understand the basic first.

[kaboom]

Re: Measuring switching frequency ?

Not on the 12V, on the ANODE of the rectifier diode for the 12V which is AC feed to the Anode of the rectifier.

Thank you, OM. That's exactly what I (and stj) said above to the OP, who's jumping in before he can swim.

May be should look up how rectifier is used and connected to an AC source to rectify an AC then you will understand where to put the probe to measure what you are looking for, need to understand the basic first.

Said the same to him in the other thread, with the fake POS external supply. His posts are almost as bad as some youtube comments. Has no idea what the hell he's doing, yet wants to be "rewarded" with constant handholding with answers to the types of questions which suggest he's got no clue.

Yes, we all started somewhere, but dammit, start small and work your way up; don't turn things into a google handhold competition, read some books and use your head. THINK about things for an entire 30 seconds, after LEARNING SOMETHING, then you'll (hopefully) arrive at some conclusion.

"Reactive and emotional" have no place in troubleshooting.