Hello, I am new to his forum!

I want to make a bench power supply from an old PSU (80s) and I wish to use its casing but is is too fit inside. I think that if I can remove the 115v circuit I can make some space but I am not sure how to do that. Tried tracing some components but with no result.

Another solution I though of is to replace some parts with smaller ones but I don't know which replaces which.

As you probable know already, I am a hobby electronics enthusiast and I don't know a lot, so any help will be welcomed.
Thank you, in advance!

 

hi org,
Welcome to AAC.
Is it an old Computer power supply.?
E

 

As you probable know already, I am a hobby electronics

Hello there,
from how you described it I fear for your safety have you ever done anything like this before? I mean working with AC mains transformers

 

Is it an old Computer power supply.?

Yes, it is.

I fear for your safety have you ever done anything like this before?

Basically no, but I think I am capable of avoiding unnecessary risks and I won't take one if I decide it is not for me.

 

hi org,
Two PDF's that may help.
As already noted, take care when working on mains power supplies, if in doubt ask!!!

E

 

What do you want to do , just make it into a 3V, 5V, 12V outputs using the same casing, .?

These supplies will run on 110V and 230V , they have a voltage select switch on the rear, what country are you in?

 

What do you want to do , just make it into a 3V, 5V, 12V outputs using the same casing, .?

These supplies will run on 110V and 230V , they have a voltage select switch on the rear, what country are you in?

I would like to use the 12v and convert it to variable 1-35V. I also would like it to has a digital voltmeter on the output and several switches and leds. USB ports will be optional if there is enough space.

I also live in Bulgaria. Here we use 220v and this is the reason I want to remove the 115v circuit from the pcb to make room for the components statet above.

 

The only part that makes it work on 115V is a switch on the case, .

Are you going to use a buck boost circuit to get 12v to 35v ??

 

The only part that makes it work on 115V is a switch on the case, .

Are you going to use a buck boost circuit to get 12v to 35v ??

Yes, I am going to use a buck/boost converter.

And I found out that the 115/230 switch work as an on/off switch. When is set to 115v it closes a circuit on the pcb but I can not trace it.

 

Hello,

This site shows a lot of ATX powersupply schematics:
http://danyk.cz/s_atx_en.html
The 115 / 230 volts switch is likely to have a rectification of the 230 Volts or a doubler for the 115 Volts.
Here is an example of the mains input circuit of an ATX powersupply:


Bertus

 

Yes, I am going to use a buck/boost converter.

And I found out that the 115/230 switch work as an on/off switch. When is set to 115v it closes a circuit on the pcb but I can not trace it.

It just connects one of the mains feeds to the centre of the two Smoothing Capacitors, and bypasses part of the bridge rectifier, as show.
It would be wise to remove the switch.

Warning! If you connected it to 115V input on a 230V supply it will Blow Up .