Maker Pro

CPU Power Supply Mod

Modification to a CPU power supply to make it into a bench top unit.

Supercap2F

Mar 22, 2014
550
Joined
Mar 22, 2014
Messages
550
Supercap2F submitted a new Showcase Item:

CPU Power Supply Mod

Howdy!

This project came out of wanting to etch my first useful PCB (up to now all the PCBs I've made have been tests). I have a old CPU power supply that's been laying around for awhile, so I decided to convert it to a PSU I could use on my bench.

First I started googling around for info on it, and found that it uses a standard computer PSU pin-out called ATX 2.x. The wikipedia article on it is here: https://en.wikipedia.org/wiki/ATX#Power_supply.

The specifications for the power supply are as follows:
  • +3.3VDC/17A
  • +5VDC/22A
  • +5VDC/2A (Standby)
  • +12VDC/18A
  • -12VDC/0.8A
  • 300W Max power
I'm planing to make all the circuitry handle about 3A maximum current draw on each voltage (I'm going to fuse it for 2.5A for now though). If I ever want to be able to draw more current then that (which is not likely), I guess will just have to modify it some more. :D
=========================================

So the first order of business - draw a schematic. Here it is:
View attachment 22136

I decided to use a PIC18F1220 for this project because I have quite a few laying around. A 1602 LCD will be used for the user interface – I'll need some way of telling the user which voltages are switched on. Three switches will work for user control (Select/up/down – or something like that).

P4 is a jumper (it connects PGD to ON1 and PGC to ON2) and is there for when the PIC is programmed – Since I ran out of I/Os I had to use the two pins that are for programming the PIC. And when the PIC is programmed, I don't want anything screwing up the communication between the computer and the PIC, so P4 should be unjumped while programming (is that even a word? :D).
=========================================

Here's the PCB layout:
View attachment 22137

Yes, I know that the fuses overlap other parts - The plan is to have the fuses mounted on the back side of the circuit board and the rest of the parts on top. The relays are just some high current ones that I salvaged from a used circuit board (I think they where out of a broken fryer to be exact).

Unfortunately, I will have to solder about eight jumpers on where I couldn't figure out how to run a trace (not shown here, but they can be seen in the KiCAD file as un-routed traces). I guess I should have tried to optimize it a little more, but space was kind of lacking...
=========================================

On to etching!
View attachment 22140View attachment 22139
The...

Read more about this showcase item here...
 

Martaine2005

May 12, 2015
4,932
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That is excellent work. Well done sir.
"unjumped" is it a word?
It is now:p I shall continue to use it..

Are you planning on another enclosure? Something fit for the best electronics benches.

Martin
 

Supercap2F

Mar 22, 2014
550
Joined
Mar 22, 2014
Messages
550
Are you planning on another enclosure? Something fit for the best electronics benches.
No, I wasn't really planing to make a custom enclosure - I was thinking along the lines of mounting the circuit board directly to the front of the PSU so you can see all the electronics stuff.

If I had a laser cutter I would probably make a case out of clear acrylic or wood, but as it stands, I haven't been able to afford one with my limited income. :D
Dan
 

Martaine2005

May 12, 2015
4,932
Joined
May 12, 2015
Messages
4,932
Hmm, wouldn't it be nice to have a lazer cutter. And the space for it too!!

I 'ONCE' left an amplifier circuit open 'to see the electronics'........:(
Sometimes when snipping off the excess leads from components, you can only find 8 out of 10.........
You 'HEAR' the other 2........Lol..:p

Martin
 

Supercap2F

Mar 22, 2014
550
Joined
Mar 22, 2014
Messages
550
I 'ONCE' left an amplifier circuit open 'to see the electronics'........:(
Sometimes when snipping off the excess leads from components, you can only find 8 out of 10.........
You 'HEAR' the other 2........Lol..:p
That's a good point. Maybe I'll try and cover up just the back side of the circuit board where the fuses will be...

Wow Dan, that's great. Look how far you have come since you joined. You should be proud of yourself.
Thanks Adam. But if it wasn't for you guys here on the forums, I probably wouldn't have come anywhere near as far! :)
Dan
 

Supercap2F

Mar 22, 2014
550
Joined
Mar 22, 2014
Messages
550
Supercap2F updated CPU Power Supply Mod

Howdy!

This project came out of wanting to etch my first useful PCB (up to now all the PCBs I've made have been tests). I have a old CPU power supply that's been laying around for awhile, so I decided to convert it to a PSU I could use on my bench.

First I started googling around for info on it, and found that it uses a standard computer PSU pin-out called ATX 2.x. The wikipedia article on it is here: https://en.wikipedia.org/wiki/ATX#Power_supply.

The specifications for the power supply are as follows:
  • +3.3VDC/17A
  • +5VDC/22A
  • +5VDC/2A (Standby)
  • +12VDC/18A
  • -12VDC/0.8A
  • 300W Max power
I'm planing to make all the circuitry handle about 3A maximum current draw on each voltage (I'm going to fuse it for 2.5A for now though). If I ever want to be able to draw more current then that (which is not likely), I guess will just have to modify it some more. :D
=========================================

So the first order of business - draw a schematic. Here it is:
View attachment 22136

I decided to use a PIC18F1220 for this project because I have quite a few laying around. A 1602 LCD will be used for the user interface – I'll need some way of telling the user which voltages are switched on. Three switches will work for user control (Select/up/down – or something like that).

P4 is a jumper (it connects PGD to ON1 and PGC to ON2) and is there for when the PIC is programmed – Since I ran out of I/Os I had to use the two pins that are for programming the PIC. And when the PIC is programmed, I don't want anything screwing up the communication between the computer and the PIC, so P4 should be unjumped while programming (is that even a word? :D).
=========================================

Here's the PCB layout:
View attachment 22137

Yes, I know that the fuses overlap other parts - The plan is to have the fuses mounted on the back side of the circuit board and the rest of the parts on top. The relays are just some high current ones that I salvaged from a used circuit board (I think they where out of a broken fryer to be exact).

Unfortunately, I will have to solder about eight jumpers on where I couldn't figure out how to run a trace (not shown here, but they can be seen in the KiCAD file as un-routed traces). I guess I should have tried to optimize it a little more, but space was kind of lacking...
=========================================

On to etching!
View attachment 22140View attachment 22139
The...

View updates to this showcase item...
 

Supercap2F

Mar 22, 2014
550
Joined
Mar 22, 2014
Messages
550
Supercap2F updated CPU Power Supply Mod

Howdy!

This project came out of wanting to etch my first useful PCB (up to now all the PCBs I've made have been tests). I have a old CPU power supply that's been laying around for awhile, so I decided to convert it to a PSU I could use on my bench.

First I started googling around for info on it, and found that it uses a standard computer PSU pin-out called ATX 2.x. The wikipedia article on it is here: https://en.wikipedia.org/wiki/ATX#Power_supply.

The specifications for the power supply are as follows:
  • +3.3VDC/17A
  • +5VDC/22A
  • +5VDC/2A (Standby)
  • +12VDC/18A
  • -12VDC/0.8A
  • 300W Max power
I'm planing to make all the circuitry handle about 3A maximum current draw on each voltage (I'm going to fuse it for 2.5A for now though). If I ever want to be able to draw more current then that (which is not likely), I guess will just have to modify it some more. :D
=========================================

So the first order of business - draw a schematic. Here it is:
View attachment 22136

I decided to use a PIC18F1220 for this project because I have quite a few laying around. A 1602 LCD will be used for the user interface – I'll need some way of telling the user which voltages are switched on. Three switches will work for user control (Select/up/down – or something like that).

P4 is a jumper (it connects PGD to ON1 and PGC to ON2) and is there for when the PIC is programmed – Since I ran out of I/Os I had to use the two pins that are for programming the PIC. And when the PIC is programmed, I don't want anything screwing up the communication between the computer and the PIC, so P4 should be unjumped while programming (is that even a word? :D).
=========================================

Here's the PCB layout:
View attachment 22137

Yes, I know that the fuses overlap other parts - The plan is to have the fuses mounted on the back side of the circuit board and the rest of the parts on top. The relays are just some high current ones that I salvaged from a used circuit board (I think they where out of a broken fryer to be exact).

Unfortunately, I will have to solder about eight jumpers on where I couldn't figure out how to run a trace (not shown here, but they can be seen in the KiCAD file as un-routed traces). I guess I should have tried to optimize it a little more, but space was kind of lacking...
=========================================

On to etching!
View attachment 22140View attachment 22139
The...

View updates to this showcase item...
 

Supercap2F

Mar 22, 2014
550
Joined
Mar 22, 2014
Messages
550
Supercap2F updated CPU Power Supply Mod

Howdy!

This project came out of wanting to etch my first useful PCB (up to now all the PCBs I've made have been tests). I have a old CPU power supply that's been laying around for awhile, so I decided to convert it to a PSU I could use on my bench.

First I started googling around for info on it, and found that it uses a standard computer PSU pin-out called ATX 2.x. The wikipedia article on it is here: https://en.wikipedia.org/wiki/ATX#Power_supply.

The specifications for the power supply are as follows:
  • +3.3VDC/17A
  • +5VDC/22A
  • +5VDC/2A (Standby)
  • +12VDC/18A
  • -12VDC/0.8A
  • 300W Max power
I'm planing to make all the circuitry handle about 3A maximum current draw on each voltage (I'm going to fuse it for 2.5A for now though). If I ever want to be able to draw more current then that (which is not likely), I guess will just have to modify it some more. :D
=========================================

So the first order of business - draw a schematic. Here it is:
View attachment 22136

I decided to use a PIC18F1220 for this project because I have quite a few laying around. A 1602 LCD will be used for the user interface – I'll need some way of telling the user which voltages are switched on. Three switches will work for user control (Select/up/down – or something like that).

P4 is a jumper (it connects PGD to ON1 and PGC to ON2) and is there for when the PIC is programmed – Since I ran out of I/Os I had to use the two pins that are for programming the PIC. And when the PIC is programmed, I don't want anything screwing up the communication between the computer and the PIC, so P4 should be unjumped while programming (is that even a word? :D).
=========================================

Here's the PCB layout:
View attachment 22137

Yes, I know that the fuses overlap other parts - The plan is to have the fuses mounted on the back side of the circuit board and the rest of the parts on top. The relays are just some high current ones that I salvaged from a used circuit board (I think they where out of a broken fryer to be exact).

Unfortunately, I will have to solder about eight jumpers on where I couldn't figure out how to run a trace (not shown here, but they can be seen in the KiCAD file as un-routed traces). I guess I should have tried to optimize it a little more, but space was kind of lacking...
=========================================

On to etching!
View attachment 22140View attachment 22139
The...

View updates to this showcase item...
 

Supercap2F

Mar 22, 2014
550
Joined
Mar 22, 2014
Messages
550
Supercap2F updated CPU Power Supply Mod

Howdy!

This project came out of wanting to etch my first useful PCB (up to now all the PCBs I've made have been tests). I have a old CPU power supply that's been laying around for awhile, so I decided to convert it to a PSU I could use on my bench.

First I started googling around for info on it, and found that it uses a standard computer PSU pin-out called ATX 2.x. The wikipedia article on it is here: https://en.wikipedia.org/wiki/ATX#Power_supply.

The specifications for the power supply are as follows:
  • +3.3VDC/17A
  • +5VDC/22A
  • +5VDC/2A (Standby)
  • +12VDC/18A
  • -12VDC/0.8A
  • 300W Max power
I'm planing to make all the circuitry handle about 3A maximum current draw on each voltage (I'm going to fuse it for 2.5A for now though). If I ever want to be able to draw more current then that (which is not likely), I guess will just have to modify it some more. :D
=========================================

So the first order of business - draw a schematic. Here it is:
View attachment 22136

I decided to use a PIC18F1220 for this project because I have quite a few laying around. A 1602 LCD will be used for the user interface – I'll need some way of telling the user which voltages are switched on. Three switches will work for user control (Select/up/down – or something like that).

P4 is a jumper (it connects PGD to ON1 and PGC to ON2) and is there for when the PIC is programmed – Since I ran out of I/Os I had to use the two pins that are for programming the PIC. And when the PIC is programmed, I don't want anything screwing up the communication between the computer and the PIC, so P4 should be unjumped while programming (is that even a word? :D).
=========================================

Here's the PCB layout:
View attachment 22137

Yes, I know that the fuses overlap other parts - The plan is to have the fuses mounted on the back side of the circuit board and the rest of the parts on top. The relays are just some high current ones that I salvaged from a used circuit board (I think they where out of a broken fryer to be exact).

Unfortunately, I will have to solder about eight jumpers on where I couldn't figure out how to run a trace (not shown here, but they can be seen in the KiCAD file as un-routed traces). I guess I should have tried to optimize it a little more, but space was kind of lacking...
=========================================

On to etching!
View attachment 22140View attachment 22139
The...

View updates to this showcase item...
 

Supercap2F

Mar 22, 2014
550
Joined
Mar 22, 2014
Messages
550
Man, it seams like it's been a loooooong time since I last posted! Been pretty busy lately...

I recently acquired a 3D printer, so I printed out a front case for the PSU - I made a (final?) update to the project log under the "project log" tab.
 

Arouse1973

Adam
Dec 18, 2013
5,178
Joined
Dec 18, 2013
Messages
5,178
Hey Dan, that looks wonderful. You have put so much hard work into your project, well done.
Adam
 

Consultant

Dec 2, 2011
9
Joined
Dec 2, 2011
Messages
9
I'm impressed!

You have done a really good job of this and you should be rightly proud.

Only thing I can add really, is that in my experience, ALL electrolytics should be replaced at the first sign of any problem, or at some "unfathomable" problem. There was a big scandal a few years ago, that for something like ten years, many electrolytics ("paralylitics"???) had been made to a very poor quality and were not lasting long. Ridiculous really, as they are some of the less reliable passive components as it is...

If you don't replace them - Especially on older items - You run a real risk of ruining a lot more components. Think of improperly smoothed DC, with peaks going out of the range of semiconductors for one thing. There's also a small risk of fires and things like that. Old TVs back in the 60s and 70s had capacitors right across the mains electricity all the time. So many house fires and deaths were caused when they dried out and caught fire. Thankfully a lot less of a risk now, but still worth changing them all, even if only one looks anything less than perfect.

There can even be a slight problem from the inrush current on older equipment, because the plates of the larger caps have to form again. I used to use a PSU and a little jig I made from some wood and aluminium to reform the plates of all my electrolytics in stock, every five years or so. I've never heard of anyone else doing that, but it's probably because I had a large stock of them I got for almost nothing, from businesses that closed down. So I had some hanging around for a lot of years. It was very educational to use a regulated voltage supply and an ANALOGUE meter to read the current. You were effectively taking ballistic measurements of the current consumption and I got to lear a fair bit, AND filter out the odd leaky one!
 

Nemo1956

Sep 5, 2016
34
Joined
Sep 5, 2016
Messages
34
I have one of these on my bench as well. I use it from time to time.
it works well and very reliable voltage source.
 
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