Removing unused leads from PCB

Melvang

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Jan 9, 2021
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Putting some serious thought into opening up my PSU and removing unwanted/unused leads. I have more unused leaded than used right now.

Anyone done this?

Before the safety police start commenting, I am well aware of the dangers of working around capacitors, and an aware of safe discharge procedures.
 

Melvang

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This is why people buy modular power supplies. Go for it :)
Don't have the disposable cash for one right now. The PSU is an older PC Power & Cooling 950 Silencer. Bought when modular first started gaining popularity but most were still using proprietary plugs at the PSU. But a bit of screwdriver action and solder work will be essentially free.
 

cdabc123

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Go for it. I would even consider just cutting the unused wires short in the psu if the soldering job looks like a pain. If the soldering job looks easy go at it and your good.
 

Melvang

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Go for it. I would even consider just cutting the unused wires short in the psu if the soldering job looks like a pain. If the soldering job looks easy go at it and your good.
Not planning on just cutting. Paranoid about wires touching and I hate dealing with tape residue. I am fairly decent with an iron. I have desoldered switches from a couple cheap alps keyboards without lifting any pads, replaced switches on a plate mount Roswill, and my Das Keybaords.
 

cdabc123

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Not planning on just cutting. Paranoid about wires touching and I hate dealing with tape residue. I am fairly decent with an iron. I have desoldered switches from a couple cheap alps keyboards without lifting any pads, replaced switches on a plate mount Roswill, and my Das Keybaords.

Not to discourage you from soldering as thats the best way to do it but you wouldnt have too worry about wires touching. If you cut them around the same length and cut cleanly the installation is enough to prevent it. I do it frequently for psus I'm using for other projects.
 

Melvang

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Not to discourage you from soldering as thats the best way to do it but you wouldnt have too worry about wires touching. If you cut them around the same length and cut cleanly the installation is enough to prevent it. I do it frequently for psus I'm using for other projects.
I realize it is probably an unnecessary paranoia, but desoldering also leaves easier installation of leads down to road in needed. Plus cleaner work.
 

Melvang

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Well, no desoldering tonight. Turns out, my tip doesn't have enough thermal capacity to melt the solder.
 
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jmilcher

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Well, no desoldering tonight. Turns out, my tip doesn't have enough thermal capacity to melt the solder.
I was going to chime in and mention, the solder they use for these commercially produced psu’s will require a heck of a hefty iron or a really hot air gun. It’s not your average temp stuff.
 

Melvang

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I was going to chime in and mention, the solder they use for these commercially produced psu’s will require a heck of a hefty iron or a really hot air gun. It’s not your average temp stuff.
Yeah, I have done lead free stuff in keyboards, just not connections with this much mass.
 

Melvang

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I was going to chime in and mention, the solder they use for these commercially produced psu’s will require a heck of a hefty iron or a really hot air gun. It’s not your average temp stuff.
What size tip would you recommend?
 

Melvang

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Use a large tip, and lots of flux
We have one electronics store in the area, going to call them tomorrow and see if they carry any larger tips for my iron. If not, I am going to call Edsyn tomorrow. I am looking at the LT341BC with proper retainer, and the LT399LF. Both of these are 0.16" wide. My current tip is only .06".
 

Format _C:

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You could convert it into modular. the easier way would be cutting the cables and attaching them to connectors that can be used later. Or you can mod the whole case https://bit-tech.net/guides/modding/building_a_modular_psu/4/

PSU remains usable if more is needed from it.

I did this quite awhile back I remember my radio buddy said to use "Aviation" connectors that are availble in up to I don't know but the max I have seen it 14 pins they are round and have a screw lock so they make a good solid connection as they are screwd tight and friction lock with the pin to hole connection also.
 

Melvang

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I did this quite awhile back I remember my radio buddy said to use "Aviation" connectors that are availble in up to I don't know but the max I have seen it 14 pins they are round and have a screw lock so they make a good solid connection as they are screwd tight and friction lock with the pin to hole connection also.
Cannon plug is the term you are looking for.
 

travm

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+1 for cut.
Cut, fold back on wire, tape. All the outputs from your psu are low voltage, so as long as you don't short anything to the case and secure them its all good. You might be able to stuff them back into the housing, or cut them off from inside the housing. I wouldn't mess around with soldering, not worth the effort, and you're far more likely to accidentally melt/burn something important.
 

Format _C:

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Cannon plug is the term you are looking for.
OK Thanks I think the ones I used were made by Ampehonal (AMP or who ever owns them today the tech industey has only a few "actual" companies left with many subdivisions of the same parent company electical wiring devices are the worst ones saying a person who almost became and electician but setled for IT)
+1 for cut.
Cut, fold back on wire, tape. All the outputs from your psu are low voltage, so as long as you don't short anything to the case and secure them its all good. You might be able to stuff them back into the housing, or cut them off from inside the housing. I wouldn't mess around with soldering, not worth the effort, and you're far more likely to accidentally melt/burn something important.

Well if you go this route just make sure any voltage wires do not touch a ground wire or the metal chassis (also DC as well as AC ground/Earth)
 

Ready4Dis

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Putting some serious thought into opening up my PSU and removing unwanted/unused leads. I have more unused leaded than used right now.

Anyone done this?

Before the safety police start commenting, I am well aware of the dangers of working around capacitors, and an aware of safe discharge procedures.
I've done this before, I just unsolder the wires and solder back in only the ones I need... if you're really bored you can even shorten them up if they are to long. I've even changed out connectors when I didn't have enough of the right kind, just keep in mind the maximum power of your PSU before adding a ton of high power connectors :p. I'm pretty handy with a soldering iron though, so ymmv. This is how I did it before modular PSU's became a thing. They've always been modular, just not as simple as plugging in a connector ;).
 
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GiGaBiTe

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Anyone done this?

All the time, you generally need a powerful iron to get it accomplished though since the large power planes plus the wires have enough mass to suck the heat out of lower powered irons quick. I use one of these bad boys for power plane work because it cuts through huge blobs of solder like a hot knife through butter:

https://www.amazon.com/Hakko-551V-V12-150W-Matchless-Soldering/dp/B00OSLFDA4

Just be VERY careful how long you hold this iron on, a couple of seconds max. It has a huge thermal mass and generally runs between 1000-1300F, so hot that the tip actually glows a dull orange.

Before the safety police start commenting, I am well aware of the dangers of working around capacitors, and an aware of safe discharge procedures.

I'm going to be the safety police because you don't seem to realize that high voltage is present in other places than just capacitors. The primary mosfet heatsink is generally in the 375V DC range and the switching transformers have high voltage, high frequency AC on them as well. It can remain charged for minutes after power down, depending on the values of the bleed resistors and if they're even working/present. Make sure you probe from both primary and secondary side heatsinks to the case before you start tearing into the unit, or you're going to get BBQ and potentially blow up the primary mosfets if you short them out. If you see voltage across the heatsinks, let the supply sit until it drops to nothing. Attempting to discharge the capacitors through the mosfet heatsink(s) can cause damage.
 

RogueTrip

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I cut off the excess wires on a 500w psu for a pentium 3 computer awhile back. Best bet is to open up the psu and cut the wires as far down to the circuit board. All the connectors come back to central point and would take a major solder gun to remove those wires.

I take no blame for anyone who hurts them self on this modification.

About to open up another psu to put a resistor on the fan to quiet it down. Wish me luck.
 
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