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#1
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Computer needs warming up.
A friend has a computer that needs to be warmed up in cold weather
before it will start. He blows hot air into it from a small electric floor-heater. Then it starts OK. What part in the computer needs fixing? |
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#2
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Computer needs warming up.
Peter Jason wrote:
A friend has a computer that needs to be warmed up in cold weather before it will start. How cold are we talking about here? He blows hot air into it from a small electric floor-heater. Then it starts OK. What part in the computer needs fixing? Bad caps? Cheap PS? -- Take care, Jonathan ------------------- LITTLE WORKS STUDIO http://www.LittleWorksStudio.com |
#3
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Computer needs warming up.
On Mon, 24 Aug 2020 22:31:17 -0400, "Jonathan N. Little"
wrote: Peter Jason wrote: A friend has a computer that needs to be warmed up in cold weather before it will start. How cold are we talking about here? It's about 10DegC The humidity is high too. He blows hot air into it from a small electric floor-heater. Then it starts OK. What part in the computer needs fixing? Bad caps? Cheap PS? |
#4
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Computer needs warming up.
Peter Jason wrote:
A friend has a computer that needs to be warmed up in cold weather before it will start. He blows hot air into it from a small electric floor-heater. Then it starts OK. What part in the computer needs fixing? Cold shrinks, heat expands. It could be anything. printed circuits, loose components, what Jonathan said, caps, IC's, CPU, Power supply, loose connector, plug, wire, Test by selectively heating small areas then narrow it down to even smaller areas, etc. |
#5
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Computer needs warming up.
Jonathan N. Little wrote:
Peter Jason wrote: A friend has a computer that needs to be warmed up in cold weather before it will start. How cold are we talking about here? He blows hot air into it from a small electric floor-heater. Then it starts OK. What part in the computer needs fixing? Bad caps? Cheap PS? There have been reports of this kind of fallout before. The motherboards are probably never verified in a temperature chamber. A suspect part of the motherboard, is the backfeed cutoff logic. This is some ad-hoc design, where the designer leaves their trademark on the board. For example, if you received an Intel sample schematic, you would not adopt their cutoff logic. You'd make your own. The cutoff logic consists of a hodge podge of diodes, bipolar transistors and MOSFETs arranged in such a way that when a computer enters shutdown, currents don't flow into the wrong parts and prevent the "sequencing" that's supposed to happen at startup. Some motherboards can't generate a RESET properly, because of problems with that part of the design. One motherboard, phantom current used to flow from the computer monitor, back into the computer, and the board would not RESET. If the monitor cable was disconnected, the computer would promptly start - then plug the monitor cable in and it's fine. Of course, the owner hates the idea of doing this forever... And if you allow a PC to get too cold, the weakest link is the hard drive. You don't particularly want to hit the "dew point" for the drive. Or cause frost to form inside. If a hard drive does get that cold, it's a good idea to let it equilibrate with normal room temp for 24 hours, just in case. You're not supposed to power it up immediately if it's full of frost. Paul |
#6
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Computer needs warming up.
On Mon, 24 Aug 2020 23:50:49 -0400, Paul
wrote: Jonathan N. Little wrote: Peter Jason wrote: A friend has a computer that needs to be warmed up in cold weather before it will start. How cold are we talking about here? He blows hot air into it from a small electric floor-heater. Then it starts OK. What part in the computer needs fixing? Bad caps? Cheap PS? There have been reports of this kind of fallout before. The motherboards are probably never verified in a temperature chamber. A suspect part of the motherboard, is the backfeed cutoff logic. This is some ad-hoc design, where the designer leaves their trademark on the board. For example, if you received an Intel sample schematic, you would not adopt their cutoff logic. You'd make your own. The cutoff logic consists of a hodge podge of diodes, bipolar transistors and MOSFETs arranged in such a way that when a computer enters shutdown, currents don't flow into the wrong parts and prevent the "sequencing" that's supposed to happen at startup. Some motherboards can't generate a RESET properly, because of problems with that part of the design. One motherboard, phantom current used to flow from the computer monitor, back into the computer, and the board would not RESET. If the monitor cable was disconnected, the computer would promptly start - then plug the monitor cable in and it's fine. Of course, the owner hates the idea of doing this forever... And if you allow a PC to get too cold, the weakest link is the hard drive. You don't particularly want to hit the "dew point" for the drive. Or cause frost to form inside. If a hard drive does get that cold, it's a good idea to let it equilibrate with normal room temp for 24 hours, just in case. You're not supposed to power it up immediately if it's full of frost. Paul Thanks to all. It's probably the humidity which has been bad this year. Does a computer generate heat when in sleep mode? |
#7
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Computer needs warming up.
Try rubbing your penis vigorously on
the video card until your sperm comes out, then try starting the computer. (Note: This only works for Nvidia cards) |
#8
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Computer needs warming up.
Peter Jason wrote:
Thanks to all. It's probably the humidity which has been bad this year. Does a computer generate heat when in sleep mode? A tiny amount. The +5VSB regulator makes heat, and does so without the fan running to remove it. The heat is contained inside the PSU, and would be a poor means to keep the entire chassis warm. The chassis will end up pretty well as cold as the room it is in. In the diagram here, it's the "Second Supply" in the lower left corner. There's a switcher using Q12 that makes a raw supervisory voltage (powers the TL494), and a 78L05 linear regulator makes +5VSB. If a computer was sleeping (S3), the power for the DIMMs is derived from +5VSB. The "Second Supply" always runs, unless the switch is off at the back, or the line cord is unplugged. http://www.pavouk.org/hw/en_atxps.html Modern supplies would be slightly more sophisticated than that, and the 78L05 would be replaced by a switching implementation instead. And that's because a modern supply makes +5VSB @ 2.5A or +5VSB @ 3.0A. My Test Machine uses 1.5A of the +5VSB while it sleeps (S3) - a machine with DDR4 should be a bit more economical than that. I would have to watch it, if trying to charge an Apple device, using the left-over power. Perhaps set it up for slow charging. My Test Machine uses 1.7W if the computer is doing absolutely nothing. If you plug in a USB stick, it draws power from +5VSB, and that's registered as a slight additional (vampire) loading. I can see these things, because the Test Machine is monitored by a Kill-O-Watt meter. Paul |
#9
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Computer needs warming up.
Paul in Houston TX wrote:
Peter Jason wrote: A friend has a computer that needs to be warmed up in cold weather before it will start. He blows hot air into it from a small electric floor-heater. Then it starts OK. What part in the computer needs fixing? Cold shrinks, heat expands. It could be anything. printed circuits, loose components, what Jonathan said, caps, IC's, CPU, Power supply, loose connector, plug, wire, Test by selectively heating small areas then narrow it down to even smaller areas, etc. There's a couple kinds of "won't start". 1) Fans not spinning when you push the button. PSU always makes +5VSB. If you overload it, by charging your Apple iPad, the +5VSB could go off. If there is no +5VSB, there is no way for the front mounted power switch to command the system to start. 2) Fans twitch when you push the power button. This is a sign the PSU has tripped out on overload. But normally, it won't recover until AC is removed and restored again. A weak power supply will do this. Normally, the situation only resolves when the PSU is replaced (heat would not normally make it work again). I have one supply here, that is "weak" like that. It can run one PC fan from the +12V, but that's all the current it can make. Maybe a quarter of an amp. 3) Fans run. Main rails come up. But, PC won't POST. This can be caused by either PSU or motherboard wired-OR Power_Good not indicating Power is Good. "Back-feed cut" mis-behavior can be tied into this one. These various causes, prevent escaping from RESET state. A PC isn't allowed to run, unless all Power_Good circuits agree that their power is good (includes motherboard regulators). If a "Back-feed cut" doesn't work right, the part of the circuit that detects loss of power and prepares for the presentation of power again, doesn't cycle properly. It still thinks the power was on the whole time. You would need a schematic to trace one of those down. And that circuitry is like a Rube Goldberg machine. Paul |
#10
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Computer needs warming up.
On 2020-08-24 18:47, Peter Jason wrote:
A friend has a computer that needs to be warmed up in cold weather before it will start. He blows hot air into it from a small electric floor-heater. Then it starts OK. What part in the computer needs fixing? Well, if you want to be fancy, put a volt meter on your motherboard power supply connector's "PWR-OK" pin and see if it switches immediately when you power up or it waits a while and switches when your computer starts to boot. "https://www.smpspowersupply.com/connectors-pinouts.html If it waits a while, replace the power supply. |
#11
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Computer needs warming up.
On 8/24/2020 9:47 PM, Peter Jason wrote:
A friend has a computer that needs to be warmed up in cold weather before it will start. He blows hot air into it from a small electric floor-heater. Then it starts OK. What part in the computer needs fixing? After reading the responses (so far) I did not see the simplest solution to this challenge. Don't turn it off!! Have a better day all...................... Les |
#12
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Computer needs warming up.
On Tue, 25 Aug 2020 07:43:22 -0400, ABLE1
wrote: On 8/24/2020 9:47 PM, Peter Jason wrote: A friend has a computer that needs to be warmed up in cold weather before it will start. He blows hot air into it from a small electric floor-heater. Then it starts OK. What part in the computer needs fixing? After reading the responses (so far) I did not see the simplest solution to this challenge. Don't turn it off!! Have a better day all...................... Les He seems to happy with the floor heater. His computer is very old anyway. |
#13
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Computer needs warming up.
On 25/08/2020 05.50, Paul wrote:
Jonathan N. Little wrote: Peter Jason wrote: A friend has a computer that needs to be warmed up in cold weather before it will start. How cold are we talking about here? He blows hot air into it from a small electric floor-heater. Then it starts OK. What part in the computer needs fixing? Bad caps? Cheap PS? There have been reports of this kind of fallout before. The motherboards are probably never verified in a temperature chamber. I have a computer that needs warming up to boot, and it is not broken. The thing is, its 30 MB hard disk uses a step motor to position the head on each track. In winter, the positions are slightly off compared to when it is warm, so there are read errors and fails to boot, till a few minutes later when the hard disk warms up. :-DDD It runs with an 8086 at 8Mhz. Well, /runs/... you know :-D -- Cheers, Carlos. |
#14
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Computer needs warming up.
You need something that can read hypertext in my posts!! Clearly you won't know this so simply move on and do something else. With over 1.2 billion devices now running Windows 10, customer satisfaction is higher than any previous version of windows. |
#15
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Computer needs warming up.
On Wed, 26 Aug 2020 05:20:51 +0100, ? Good Guy ?
wrote: You need something that can read hypertext in my posts!! Clearly you won't know this so simply move on and do something else. With over 1.2 billion devices now running Windows 10, customer satisfaction is higher than any previous version of windows. I've never heard of "hypertext"; what is it and why do I need it? |
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