fiza Posted September 9, 2019 Posted September 9, 2019 Since the start of term we have found that a number of computers in our ICT Suites will not power on if switched off. The plug has to be unplugged and then plugged in again and then the power returns. We use Stone Computers which are not that old and it has never happened before. Has anyone seen this kind of thing before?
FishCustard Posted September 9, 2019 Posted September 9, 2019 Yes, I have. It's almost certainly caused by el cheap-o PSUs. What can happen is that while plugged in the capacitors in the bridge rectifier of the PSU can remain charged (even if the PC itself is off), leading to the PSU DC supply rails remaining energised. On cheapy ones, the over-current protection can trigger erroneously if the PC is turned on when the rails are energised (thus cutting the power). In one case this was down to the manufacturer reusing the OCP for the 12V rail for the 5V rail, stepping it down accordingly - the resulting circuit was (a) too sensitive, and (b) didn't discharge the capacitors quickly enough. You should be able to speed up the capacitor discharge by shorting the live and neutral pins of the connector on the back of the PC with something (be careful - if you end up in the circuit you can get a nasty jolt). TL;DR - cheapy PSUs, try swapping them out. 3
chazzy2501 Posted September 9, 2019 Posted September 9, 2019 I have a few HP 800s that do this, they only work once, if you shutdown it'll never turn on again unless removed from the mains. I toyed with S modes and fast start but nothing.
Ditto Posted September 9, 2019 Posted September 9, 2019 Since the start of term we have found that a number of computers in our ICT Suites will not power on if switched off. The plug has to be unplugged and then plugged in again and then the power returns. We use Stone Computers which are not that old and it has never happened before. Has anyone seen this kind of thing before? Are they in the warranty period - or less than 2 years old? I'd be looking at getting the supplier to resolve if so.
HTCPCP Posted September 9, 2019 Posted September 9, 2019 Had some zoostorms that did exactly the same - PSU's were the cheapest they could find, from a company that if you googled it, didn't come up with any search results. Swapped them for the cheapest psu from a reputable brand (often Corsair) as and when they started to fail
FishCustard Posted September 9, 2019 Posted September 9, 2019 I believe the ones I encountered were Zoostorm Deltas as well...
IrritableTech Posted September 9, 2019 Posted September 9, 2019 @fiza We're having this issue with just a handful of our Stone PCs as well. Literally just half a dozen out of the 100 or so we ordered in 2015 but they all sit in the same room. We've been trying to narrow the issue down without much success. 1
FishCustard Posted September 9, 2019 Posted September 9, 2019 Try swapping the PSU for one from a different brand and see what happens.
fiza Posted September 10, 2019 Author Posted September 10, 2019 Try swapping the PSU for one from a different brand and see what happens. All still under warranty with Stone so don't really want to start swapping PSUs. @IrritableTech - would be interested to see what conclusion your investigation comes to.
IrritableTech Posted September 10, 2019 Posted September 10, 2019 All still under warranty with Stone so don't really want to start swapping PSUs. @IrritableTech - would be interested to see what conclusion your investigation comes to. I'll do a swap and report back anything of note.
Mildlyoktech Posted September 10, 2019 Posted September 10, 2019 Since the start of term we have found that a number of computers in our ICT Suites will not power on if switched off. The plug has to be unplugged and then plugged in again and then the power returns. We use Stone Computers which are not that old and it has never happened before. Has anyone seen this kind of thing before? Having that in spades where I work, large numbers of 4-5 year old PC's. Having a stone engineer come around every two weeks or so to replace a powersupply. I remmeber about 5 years ago I had the same issue with a number of Viglen PC's In the end Viglen sent us a box of 100 replacement power supplies becuase the engineer visits were too frequent
Techie-v2 Posted September 10, 2019 Posted September 10, 2019 We have also seen this with a batch of ZooStorm PC's. I used to fascinate one of out science technicians by showing him that swapping the power lead between the PC and monitor fixed it. Obviously the time spent unplugged whilst swapping the cables was enough to discharge the PSU I knew that but it fooled him! 1
fiza Posted September 21, 2019 Author Posted September 21, 2019 We had the Stone Engineer visit and he updated the BIOS. Since then the machines have booted up each morning with no issues.
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