problem measurement part frequency victor vc97

[ZipZapOuch]

Sorry, but using a multimeter in a completely inappropriate way and killing it is a very rookie mistake - I wouldn't consider anyone doing that 'knowledgeable in repairs'.

That was true in the past because few meters would read frequencies past $20kHz. Newer meters (like this one) can read line voltages and up to 30MHz. A frequency counter IS a reasonable first step for the OP's project if he doesn't have a scope. The strong (Low impedence) signal from the PWM drive circuit will largely wipe out any RF interference and a reasonable frequency and duty cycle measurement should be possible at 2MHz and below (where most SMPS operate).

I'm guessing there is a manufacturing error or operator error involved here - not an inappropriate use case - and especially not a completely inappropriate use case.

 

[Nigel Goodwin]

That was true in the past because few meters would read frequencies past $20kHz. Newer meters (like this one) can read line voltages and up to 30MHz. A frequency counter IS a reasonable first step for the OP's project if he doesn't have a scope. The strong (Low impedence) signal from the PWM drive circuit will largely wipe out any RF interference and a reasonable frequency and duty cycle measurement should be possible at 2MHz and below (where most SMPS operate).

I'm guessing there is a manufacturing error or operator error involved here - not an inappropriate use case - and especially not a completely inappropriate use case.

I would still say completely inappropriate, as there's no reason whatsoever to attempt to measure the PWM frequency, and sticking a low voltage frequency counter on the high voltage collector/drain of a mains PWM switch is pretty well guaranteed to kill it.

 

[ZipZapOuch]

I would still say completely inappropriate, as there's no reason whatsoever to attempt to measure the PWM frequency, and sticking a low voltage frequency counter on the high voltage collector/drain of a mains PWM switch is pretty well guaranteed to kill it.

If a SMPS is not working, the first thing I check is the PWM signal into the mosfet gate (which is never above 20v). I'd like to understand your aggressive anti-frequency counter position someday - you must have repaired the kind that used mosfet drivers in excess of the meter's specified 250v (assuming "high voltage" is over 250v in your point of view. Note, the OP never said Drain/source.

 

[Tony Stewart]

trace the signal to find where it leads or stops with another meter

 

[Nigel Goodwin]

If a SMPS is not working, the first thing I check is the PWM signal into the mosfet gate (which is never above 20v). I'd like to understand your aggressive anti-frequency counter position someday - you must have repaired the kind that used mosfet drivers in excess of the meter's specified 250v (assuming "high voltage" is over 250v in your point of view.

Not 'aggressive', just that there's zero point in trying to measure the frequency of the PWM, it's of no use at all in repairing a SMPSU - and depending on type, may very well vary wildly as it regulates.

Note, the OP never said Drain/source.

Neither did I, perhaps you should try reading before you post?.

 

[electronium]

One thing I noticed just now, when the selector is on V true rms, push botton select orange color it shows the city electricity frequency correctly, but when the selector is on Hz, it does not show the frequency.
It is strange!!!!!!؟؟
video test and analyze device

 

[ZipZapOuch]

One thing I noticed just now, when the selector is on V true rms, push botton Duty orange color it shows the city electricity frequency correctly, but when the selector is on Hz, it does not show the frequency.
It is strange!!!!!!؟؟
video test and analyze device

Both numbers will be 50. An AC wave is 50Hz and 50% duty cycle. How is your meter connected when you get these results?

 

[electronium]

Both numbers will be 50. An AC wave is 50Hz and 50% duty cycle. How is your meter connected when you get these results?

It doesn't work on the frequency meter, but it shows the true rms frequency on the AC voltage. It has nothing to do with the duty cycle. The orange select button has dual mode.

 

[electronium]

Greetings to the colleagues of the forum
Friends, the frequency section of the multimeter works fine now. I am wondering... I measured the gate frequency of the MOSFET board of the amplifier and it is showing.
I'm both happy and surprised why it doesn't show the electricity of the city. I thought there was a problem with the frequency meter. I appreciate your help and guidance from all my friends and colleagues in this thread.
video test and analyze mutimeter vc97