Question Semi-modular PSU only semi-works

Jan 4, 2020
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I bought a semi-modular PSU used (guy claimed it "worked great" and then ghosted me) and am having trouble with it.

The permanent CPU (8pin) and Mobo (24pin) cables are working fine. I know this because if I power the HDD with an alternate power source the PC will boot and run fine.

Unfortunately, ALL of the modular slots will not deliver power (or are shorted), I tried multiple cables in every slot.

The odd thing is that it's a single rail 12v system so the main rail could not have failed. I opened it and cleaned it and did not find any problem on visual inspection (fuse, capacitors, no loose wires or damaged components.)

It's a Thermaltake Toughpoeer 750w Semi-Modular PSU with a single 12v 62A rail. MN: TP-750AH3CCG-B.

This was supposed to be a gift for my dad and can't afford to replace it.

Can I fix it?
 
Unfortunately, ALL of the modular slots will not deliver power (or are shorted), I tried multiple cables in every slot.
Are you using the specific modular cables for this PSU? Although it may seem other cables fit. There is no set standard for modular PSU pinout. So, you must use cables built for that PSU. As they are wired correctly to go from the proprietary PSU pinout to the standardized pinout for devices (PCIe, EPS, SATA, Molex, &c).

If you don't have the correct cables but ones which fit. You can rewire them yourself. You'll need a multi-meter to check voltages. Then you can rewire the cable ends going to the PSU. So, that the resulting voltages and grounds on the various connectors are correct.

If the cables are the correct ones and there simply is no power. Then the PSU is likely shot. While it would technically be possible to repair. You'd need to know how to open it up, solder, desolder and test electrical components. Along with owning all the necessary tools and testing equipment.
 
Jan 4, 2020
2
0
10
0
Are you using the specific modular cables for this PSU? Although it may seem other cables fit. There is no set standard for modular PSU pinout. So, you must use cables built for that PSU. As they are wired correctly to go from the proprietary PSU pinout to the standardized pinout for devices (PCIe, EPS, SATA, Molex, &c).

If you don't have the correct cables but ones which fit. You can rewire them yourself. You'll need a multi-meter to check voltages. Then you can rewire the cable ends going to the PSU. So, that the resulting voltages and grounds on the various connectors are correct.

If the cables are the correct ones and there simply is no power. Then the PSU is likely shot. While it would technically be possible to repair. You'd need to know how to open it up, solder, desolder and test electrical components. Along with owning all the necessary tools and testing equipment.
Yes I'm using original cables. There is likely some power to the modular circuit board because there was a spark when I initially powered one of the HDD (drive was fine.)
My question is what would have failed if the core PSU components are fine (is the 12v rail still works) but the modular supplies don't work. Could I find a replacement modular plug board?
 

mangaman

Reputable
Jun 13, 2015
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Yes I'm using original cables. There is likely some power to the modular circuit board because there was a spark when I initially powered one of the HDD (drive was fine.)
My question is what would have failed if the core PSU components are fine (is the 12v rail still works) but the modular supplies don't work. Could I find a replacement modular plug board?
Either someone overloaded the PSU to it's maximum ratted wattage, or intentionally sorted the modular parts of the PSU. You could take it to a PSU specialist to see if they can fix it (not sure if they exist or not). Most likely a fuse is blown, but something else could be the culprit.

However either way, it's best you or your father not use the PSU. The PSU could have more issues that you don't know about, and would be only a matter of time until your system gets fired by it.

Where did you get this PSU from? Is it a private or commercial reseller? If you purchased it on Ebay or Amazon, you can contact customer support and get a full refund.
 
Yes I'm using original cables. There is likely some power to the modular circuit board because there was a spark when I initially powered one of the HDD (drive was fine.)
My question is what would have failed if the core PSU components are fine (is the 12v rail still works) but the modular supplies don't work. Could I find a replacement modular plug board?
How did that happen? Did you plug in a HDD with the computer running? If so you fried it!
 

Zizo007

Notable
Feb 23, 2019
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I bought a semi-modular PSU used (guy claimed it "worked great" and then ghosted me) and am having trouble with it.

The permanent CPU (8pin) and Mobo (24pin) cables are working fine. I know this because if I power the HDD with an alternate power source the PC will boot and run fine.

Unfortunately, ALL of the modular slots will not deliver power (or are shorted), I tried multiple cables in every slot.

The odd thing is that it's a single rail 12v system so the main rail could not have failed. I opened it and cleaned it and did not find any problem on visual inspection (fuse, capacitors, no loose wires or damaged components.)

It's a Thermaltake Toughpoeer 750w Semi-Modular PSU with a single 12v 62A rail. MN: TP-750AH3CCG-B.

This was supposed to be a gift for my dad and can't afford to replace it.

Can I fix it?
Why would you buy a used cheap PSU?
Always test used components if its to be paid cash. You can open a paypal dispute after up to 6 months on any item you purchase using paypal. I very rarely buy used stuff with cash.
 

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