ATX power supply

[Vedran1]

Hey,

Ante and audioguru I think attached pdf will be very interesting to you as it was to me! I figure out some things reading it!

Enyoj! Bye! ;D

Keep posting and helping me

...:::Vedran:::...

Using_an_ATX_computer_power_supply_to_make_a_scalable_mult.pdf

 

[audioguru2]

Hi Vedran,
The FryGuy has an interesting way to get lots of power.

I don't like to short together the outputs of power supplies without resistor or diode isolation. They won't have exactly the same output voltage so the higher one will "hog" the load current.
I also don't like to short the output of a TTL gate to ground without an isolation (current-limiting) resistor.
His description of PS-ON is the opposite to the description on your earlier schematic. Which way is yours?

It will be very difficult for you to repair your PS unless you have its exact schematic. There are differences between them such as the opposite PS-ON function, and whether the +5V standby comes directly from mains AC (with a small mains transformer) or mains rectified DC (with an HV oscillator feeding a small transformer).

 

[Vedran1]

I forget to ask you: What is MOV?

Thanks

 

[audioguru2]

Hi Vedran,
A Metal Oxide Varistor (MOV) is a voltage surge arrestor that quickly limits a voltage to its rating. Its effect on AC voltages is similar to two back-to-back zener diodes. Its small size limits the amount of time it can withstand an overvoltage condition without damage, so it is used only for arresting short duration surge spikes. It looks similar to a ceramic capacitor but maybe thicker. Sometimes its symbol is a capacitor in a circle. ;D

 

[Vedran1]

Yeah i think that was my mistake!!! I thinh that was burned not capacitor... but i don't know what type should i put????
Look at attached picture on one of my before posts i wrote sybmols I can read, ones I can't read are ?
So maybe that was the problem! Yeah it was thicker than regular capacitor.... It was green.... and it was on AC part of schematic....

Thanks! Bye! ;D

...:::Vedran:::...

 

[audioguru2]

Hi Vedran,
You wrote "221J", which would make it a 220V 5% MOV. It would safely limit voltage spikes on the 115VAC side of the circuit, which is half the circuit when 230VAC is used. Its diameter determines its power handling ability. ;D
Since your PS doesn't work without it, it's too bad that more stuff must be broken. :'(

 

[Vedran1]

I don't get it? PSU sholud work fine without MOV?? Now there is capacitor instead MOV :-\

 

[audioguru2]

Hi Vedran,
A MOV is for overvoltage protection from spikes, there is not a capacitor inside, its symbol just looks like a capacitor with a circle around it. The PS should work fine without it until lightning strikes your mains, or until your refrigerator turns off making a voltage spike.

A cheap surge arrestor was being made to be plugged into a mains outlet. It had a window to see the MOV inside. A label on it said, "If it turns black, send it back".
If it ever turns black, whatever you had plugged into it to be protected by it would also be destroyed! ;D
Good surge arrestors have a fairly big and expensive gas-tube inside, or 3 of them and 3 MOVs.

I have some telephone answering machines that were blown-up by lightning. The circuit doesn't work but the MOVs and small gas-tube are OK. The gas-tube protected the MOVs but not the circuit! ;D

 

[Vedran1]

;D ;D ;D

So can I short circuit it? Maybe it doesen't work now with capacitor on its place because it has infinite resistance and MOV doesn't have infinite resistance ???

 

[Vedran1]

What is NTCR1 on schematic?? Post me a little picture plese so i can find it easily!

 

[Vedran1]

Hello!

If somebody is interested here is some text about how ATX PSU is functioning!

Bye ;D

atx2_03.pdf

 

[audioguru2]

Hi Vedran,
Do not short the MOV! It is normally open circuit but limits voltage to its rating during high voltage spikes. It never completely conducts like a short.

NTCR1 should be easy to find. It is connected in series with the mains neutral wire. Sorry, I don't know what it looks like.

 

[Vedran1]

Hello!

So NTCR1 is thermisotr for 230V?? Here i attached english version of text that came with schematic, but here is only half of schematic but if somebody needs it, it is whole in Ukrains version!

Bye! ;D

 

[ante1]

Vedran,

The