Modifying PC ATX PSU
June 21, 2015 04:01PM
I read somewhere that powering the heatbed through the ramps, supposedly the green connectors are not rated for the amps. (fire hazard)

Somebody stated to seperate colour / use all the wires, or the current is not enough.

My psu 450W it has a switch

10 yellow - I would like to save 1 of these for future arduino power
18 black
8 red
4 orange
1 blue
1 purple
1 grey - 5.15v I intend to have an led
1 green - power on
1 brown

Do I need to bridge the orange and brown, as it was in the connector.

I think my ramps 1.4 needs 5A 11A at 12V,

how many black / yellow wires should I use on 4 ramps power terminals.

also would like to use connector blocks inside the psu and use 240v mains wire to the ramps is that ok
Attachments:
open | download - atx.jpg (418.2 KB)
Re: Modifying PC ATX PSU
June 21, 2015 08:22PM
You know, if you have to say firehazard its probably not a good idea..
[store.makerstoolworks.com]

It concerns me that you're talking like you're not going through your electronics. Are you doing a rubber bed plate with a SSR?
Re: Modifying PC ATX PSU
June 21, 2015 11:10PM
All the videos I have watched, some are just using a couple 12v wires to ramps. Others have grouped all the yellows / blacks and spliced into larger guage wires.



each yellow wire maybe 2 amps, yellows are 22A in total, does it not matter if I go over the 11A or 5A on the ramps.

I want to use power cord live neutral outut connector block mounted inside atx psu

my heatbed is mk2b wired for 12v no silicon just boro glass

Edited 1 time(s). Last edit at 06/21/2015 11:12PM by Xecut0r.
Re: Modifying PC ATX PSU
June 22, 2015 02:55AM
There are many Online Journals that can help you related to your projects. Am also a electronic engg. i always use to take helps from journals based on EEE.
Re: Modifying PC ATX PSU
June 22, 2015 04:57AM
I have dismantled and re-used alot of ATX power supplies and one thing I know for sure is that all 12V and 5V wires connect to the same point on the circuit board.
So it really does not matter how many wires you join as long as they are rated for the current drawn.
If in doubt just open the power supply, unsolder all wires you don't need and replace the power wires with something of proper wire guage for the job.
Any for short distances under 30cm it does not matter too much if you use one or two of the original wires.
IMHO the best option for a conversion into a normal power supply is to remove all unwanted wires and to add a suitable connector for the power cable to the printer.
Even heavy duty speaker connectors do the trick here and are easy to mount, same for those screw type banan connectors as used on lab power supplies.

250W at 12V means around 20A going through a cable.
Everyone with a diesel engine knows jumper wires need to be thick to get the engine going from a dead battery.
So, if you have heated bed, printer and all on the same power supply it would make sense to choose the wire gauges accordingly to the power requirement of the attached devices.
You can find quite a few tables and recommendations online in regards to cable lenghts, ampere drawn and voltage.
Re: Modifying PC ATX PSU
June 23, 2015 01:23PM
Quote
Downunder35m
I have dismantled and re-used alot of ATX power supplies and one thing I know for sure is that all 12V and 5V wires connect to the same point on the circuit board.
Unless you have a split rail power supply, in which case what you know for sure is wrong. Be sure to check the nameplate ratings, silk screen, etc for indication if the 12V rail may be split. If it is, keep the rails wires separate lest bad things happen.
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