TV power supply testing

[budm]

This is how I test the power supply.
I use #1157 lamp LO filament connections, it is about 8 Watts loading (you can use less wattage). The lamps may blink at first due to the low cold ressistance of the filament , then they should come on and stay on. Use GFI outlet for safety.

[tibimakai]

Re: TV power supply testing

Excellent work.
Now where do you put the black probe from the DMM to test the primary and secondary side of a power supply.
These should be stickied.

[budm]

Re: TV power supply testing

On the AC primary side which is isolated from the Secondary (COLD) side, you use the Neagtive leg of the MAIN DC filter as the ground point (this Ground point IS NOT TIED TO THE CHASSIS) for the primary circuits.
The circuits ground for the secondary side, in most case, the 5VSTB GND, 12VDC GND, 24VDC GND are usually tied together and then tied to the TV chassis through the board mounting holes, but you should Ohm that out as you have found on your power supply. Otherwise the Negative legs of the DC filter caps for the secondary side will be you circuits ground for the cold side. tibimaki, I still like to see how you cold side ground of your VIZIO power supply is hooked up.

[tibimakai]

Re: TV power supply testing

I will make a picture, but I'm at work right now.
How come my meter shows KHZ on a V scale(my meter is not auto range) when I'm trying to measure components on the primary side using the negative of the big capacitor? It's a B&K, nothing fancy.
I have messed up my meter?

[budm]

Re: TV power supply testing

You must have accidentally hit the HZ (FREQUENCY COUNTER FUNCTION) button, so the meter becomes a frequency counter. What brand is the meter?
Yes the negative leg of the primary side mian DC filter cap is your circuit ground point for the primary side.

[tibimakai]

Re: TV power supply testing

It's a B&K Precison.
There are no buttons, it's the rotary selector style.
If I measure a FET it's even making a whisle type of sound.

[budm]

Re: TV power supply testing

Model number?

[tibimakai]

Re: TV power supply testing

I don't have it with me.

[kueberco]

Re: TV power supply testing

This is how I test the power supply.
I use #1157 lamp LO filament connections, it is about 8 Watts loading (you can use less wattage). The lamps may blink at first due to the low cold ressistance of the filament , then they should come on and stay on. Use GFI outlet for safety.

What is the resistor value you are using? Thanks

[budm]

Re: TV power supply testing

I use 1K, you can use 2K or 3K will work. At 1K it will limit the base drive current to 5mA (5V/1000 = 5mA) MAX.

[tibimakai]

Re: TV power supply testing

OK the model number is BK Tool Kit 2706A. Mine is black though.
http://www.bkprecision.com/products/...5--w-temp.html

[budm]

Re: TV power supply testing

I look at the spec, the meter can do Frequency counter function when you select the knob to "40KHz", otherwise I do not believe you should see KHz on the screen. Do see that on ALL mode? Otherwise remove the batteries to see if it will reset the meter.

[tibimakai]

Re: TV power supply testing

I will do that.
It only happens when I measure the primary side.