Can case short PSU? System won't turn on when PSU mounted in case.

home_builder

Honorable
Oct 24, 2013
12
0
10,510
I am in the process of building a budget HTPC, as a combination of older components and some new upgrades. (I have build and repaired dozens of PCs over the years.)

I breadboarded the whole lot and it works like a dream, but only whilst breadboarded. However, when I mount the PSU in the chassis, the system won't turn on (in fact it does absolutely nothing when I press the power switch, not even a fan whir). The same (nothingness) happens if the PSU is just stting in the case, touching the case metal. All the other components are securely mounted in the case. If I take the PSU out of the case so that it isn't touching any metal, the system boots up fine and works like a charm again. Note that I do not change any wiring at all in moving the PSU out of the he case, I simply stop it from making contact with the case.

I tested an older PSU in the system, and it boots up fine. However, this old PSU can't supply enough power so it is very unstable - which is fine as I was only using it to test if it also had a problem when in the case and it doesn't.

Does this mean my PSU is screwed and unsafe to use? Please note that it doesn't appear to be faulty in any way other than this, and works reliably when not touching the case. I'd rather avoid the expense of a new PSU if I can avoid it.

Or is it safe to use if I place some insulating material between it and the case?? If so any advice on what material to use, or how to attach the PSU to the case? (obviously screws will short it to the case again).

Many thanks in advance.


 
Solution
Yes the PSU has a ground fault and should not be used! If the PSU is not in warranty you can open it up and see what the problem is, disconnected from wall power of course.

home_builder

Honorable
Oct 24, 2013
12
0
10,510
Wow thank you for the quick answers.

It's a thermaltake 430NP-A2 (430W).

Rolli59 I presume a ground fault means there is a wire or component inside the PSU shorting to the case of the PSU itself? I am curious so will turn if off and see if there is anything obvious. This is what I had assumed but wanted to get a second opinion first.
 

home_builder

Honorable
Oct 24, 2013
12
0
10,510
SR71 - thank you. If I want advice on a replacement PSU should I start another thread?

Because the system has run stably with the current 430W PSU, I'm assuming that any replacement PSU that is 430W or more should be fine. Any thoughts or counter to this logic?
 

Dark Lord of Tech

Retired Moderator
PCPartPicker part list / Price breakdown by merchant / Benchmarks

Power Supply: Enermax 450W ATX12V Power Supply ($35.98 @ Newegg)
Total: $35.98
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-10-24 18:46 EDT-0400)


or


PCPartPicker part list / Price breakdown by merchant / Benchmarks

Power Supply: Corsair CX 430W 80 PLUS Bronze Certified ATX12V Power Supply ($22.50 @ Newegg)
Total: $22.50
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-10-24 18:48 EDT-0400)
 

home_builder

Honorable
Oct 24, 2013
12
0
10,510
Thank you to both of you for the recommendations. I am in the UK but will look for similar PSUs here.

The only reason I was using the Thermaltake was that it is quiet, seemed stable and was a freebie.

Noise is my primary concern for a replacement - but so long as they are no louder than the Thermaltake that's fine. I'm assuming anything sold now is whisper quiet.

One other issue is that the HTPC case I have bought mounts the PSU at the front to squeeze in full ATX MB. As such, the PSU fan cannot work in the normal way (drawing air through the case) - it's 1cm from the rear wall (bottom) of the case or directly sandwiched against the optical drive. It looks like all new PSUs have the fans in the bottom now - any suggestions on how to approach this or should I just leave it facing the bottom of the case and ensure the rest of the case is well cooled? I suppose the only thing I can do is buy the most efficient PSU I can so that there is less heat to dissipate.
 

home_builder

Honorable
Oct 24, 2013
12
0
10,510
I have just realised that PC part picker website also shows UK prices.

Unfortunately noise information isn't readily available so I will do a bit more digging to find out how noisy the ones you have suggested are.
 

home_builder

Honorable
Oct 24, 2013
12
0
10,510
Thanks - will do. It seems the CX430M is (subjectively) very quiet from the reviews on Amazon so I will order one and report back. Since it's efficient hopefully there won't be any heat dissipation issues in my unusual case. (The case was the only low profile case I could find that would take full PCI cards (DVB-S2 twin tuner), a full ATX board (freebie) - room for multiple HDDs (in case I repuprose it as a server downstream)).

Thanks again for all the great and rapid advice. I will mark this thread solved once I've installed the new PSU and tested the rig. (It would be odd to post back to a solved thread)
 

home_builder

Honorable
Oct 24, 2013
12
0
10,510
Hi everyone. Thanks for the advice. Just to update I have the CX430 on order. In meantime (before it arrives) I have been able to borrow an older PSU which I switched in - this works perfectly so it was a case shorting the faulty PSU.

I do now have a different issue of occasional system freezes (causing a totally unresponsive system which needs hard power off). However I will start a different thread for that as I don't think it is PSU related.