Can someone explain to me this?

[megajocke]

Whose are those voltage and current markings in red? That's what a normal multimeter probably would show at that kind of frequency.

[PMA]

Joe Dirt is right, DC voltmeters usually do not read AC voltages ...

[li_gangyi]

Yeah...try switching ur range to AC and then re-measure...tell us what you get...

[iso_510M]

Use an oscilloscope and you'll see a high frequency (40KHz ?) modified sine wave around 30Vp-p, with respect to ground. (42V x .707). Have repaired many, many 12V amplifiers

Jim

[li_gangyi]

Problem is...he does not have a Scope...

[Jay]

Li_gangyi, I think MaXiZ needs the answer, not the scope

[audiofan]

Voltage at the transformer is AC must be measured with an AC voltmeter that can work at the working frequency. Same applies to the current flowing from tranformer to the diode. You have DC voltage and current only at the output of the full wave bridge them you may measure with DC voltmeter

[li_gangyi]

Yeah...just change ti to AC and try and see the voltage...we would actually want you to have a scope to look at it better...but I guess he doesn't have one...