Need little help with an old Switchable PSU

Thread Starter

orgamisho

Joined Nov 25, 2020
7
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!
 

Dodgydave

Joined Jun 22, 2012
9,956
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?
 

Thread Starter

orgamisho

Joined Nov 25, 2020
7
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.
 

Dodgydave

Joined Jun 22, 2012
9,956
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 ??
 

Thread Starter

orgamisho

Joined Nov 25, 2020
7
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.
 

Dodgydave

Joined Jun 22, 2012
9,956
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 .
 
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