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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Odd PC Voltages
The PSU on my wife's old Sony PCV RX766 blew in the recent power outage here
on Oahu. A Sony replacement PSU is too expensive but I made a generic fit OK. PC seems stable and works fine. In testing with the latest Everest, I get some odd results: CPU temp is 53 degrees C. Seems high. I added an extra fan. Still high. MB is 34 degrees C. HD is 35 degrees C. More perplexing are the negative voltages: CPU Core 1.48 Aux 3.09 +3.3 3.33 +5 5.08 -12 -9.32 -5 -7.71 +5 S/B 4.44 I don't see a + 12 or +5 displayed. The -12 and -5 seem way odd since eveything works well. Shouild I be concerned? Thank you for any comments -- Remove -NOSPAM- to contact me. |
#2
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Odd PC Voltages
More perplexing are the negative voltages:
CPU Core * *1.48 Aux * * * * * * 3.09 +3.3 * * * * * *3.33 +5 * * * * * * * 5.08 -12 * * * * * * -9.32 -5 * * * * * * * -7.71 +5 S/B * * * * 4.44 I don't see a + 12 or +5 displayed. *The -12 and -5 seem way odd since eveything works well. Shouild I be concerned? I would not worry about that. However you could measure them with a reliable voltmeter to be sure. -12V are used for the serial port, if you have something connected there like a serial mouse that could explain the voltage drop. If it works, leave it as is. I think there is nothing nowadays using the -5V rail so that could explain it is slightly higher. |
#3
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Odd PC Voltages
John Keiser wrote:
The PSU on my wife's old Sony PCV RX766 blew in the recent power outage here on Oahu. A Sony replacement PSU is too expensive but I made a generic fit OK. PC seems stable and works fine. In testing with the latest Everest, I get some odd results: CPU temp is 53 degrees C. Seems high. I added an extra fan. Still high. MB is 34 degrees C. HD is 35 degrees C. More perplexing are the negative voltages: CPU Core 1.48 Aux 3.09 +3.3 3.33 +5 5.08 -12 -9.32 -5 -7.71 +5 S/B 4.44 I don't see a + 12 or +5 displayed. The -12 and -5 seem way odd since eveything works well. Shouild I be concerned? Thank you for any comments either you using your DMM incorrectly with the common probe placement or you have an issue with the - output side the supply.. Looking at the -12 line and seeing it's only -9.32 volts, this maybe due to excessive load, the -5 line being over voltage could be a by product of the PSU trying to correct the -12 and the -5 is regulated on it's own. I would worried about the -5 being high.., I think you should correct that. http://webpages.charter.net/jamie_5" |
#4
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Odd PC Voltages
John Keiser wrote: The PSU on my wife's old Sony PCV RX766 blew in the recent power outage here on Oahu. A Sony replacement PSU is too expensive but I made a generic fit OK. PC seems stable and works fine. In testing with the latest Everest, I get some odd results: CPU temp is 53 degrees C. Seems high. I added an extra fan. Still high. Hardly high for Hawaii ! Silicon functions up to vastly higher temps than that. Why do you think it's high ? MB is 34 degrees C. HD is 35 degrees C. More perplexing are the negative voltages: CPU Core 1.48 Aux 3.09 +3.3 3.33 +5 5.08 -12 -9.32 -5 -7.71 +5 S/B 4.44 I don't see a + 12 or +5 displayed. Yes, the +5 is +5.08. You could buy a cheap DMM and measure the +12 on an unused drive connector if it worries you ! The -12 and -5 seem way odd since eveything works well. Negative voltages are hardly ever used these days so it's probably 'out of regulation' due to no load. Graham |
#5
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Odd PC Voltages
Jeroni Paul wrote: -12V are used for the serial port They usually have their own charge pumps these days. Remember the spec goes back to 1982 or so. Graham |
#6
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Odd PC Voltages
Jamie wrote: I would worried about the -5 being high.., I think you should correct that. **** as usual. NOTHING uses -5V these days AFAIK. I think it was needed for very early DRAM, that's all. Graham |
#7
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Odd PC Voltages
Eeyore wrote:
Jamie wrote: I would worried about the -5 being high.., I think you should correct that. **** as usual. NOTHING uses -5V these days AFAIK. I think it was needed for very early DRAM, that's all. Graham And you would gamble on that? For your info ass, I have recent PC and the -5 is very well used in it. http://webpages.charter.net/jamie_5" |
#8
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Odd PC Voltages
On Sun, 28 Dec 2008 20:56:27 -1000, "John Keiser"
put finger to keyboard and composed: The PSU on my wife's old Sony PCV RX766 blew in the recent power outage here on Oahu. A Sony replacement PSU is too expensive but I made a generic fit OK. PC seems stable and works fine. In testing with the latest Everest, I get some odd results: CPU temp is 53 degrees C. Seems high. I added an extra fan. Still high. MB is 34 degrees C. HD is 35 degrees C. More perplexing are the negative voltages: CPU Core 1.48 Aux 3.09 +3.3 3.33 +5 5.08 -12 -9.32 -5 -7.71 +5 S/B 4.44 I don't see a + 12 or +5 displayed. The -12 and -5 seem way odd since eveything works well. Shouild I be concerned? Thank you for any comments The first thing you should do is to compare your readings with what BIOS tells you. The motherboard's hardware monitor chip probably has a multi-input A/D converter with an internal 4.096V precision reference. This means that any voltage outside the range of 0V to 4.096V has to be scaled down via an external potential divider. The Vcore and 3.3V inputs could be measured directly, but the others cannot. Negative voltages would require a DC bias. The potential divider ratios would be known to the BIOS but not to Everest. Hence the BIOS readings can probably be trusted, but not those of any software tool. Remember also that the hardware monitor is seeing these voltages as they appear on the motherboard, not at the PSU. Hence you need to be aware of voltage drops in the cables and in the motherboard traces. I prefer to use Motherboard Monitor, but unfortunately support for it ceased many years ago. MBM 5 allows you to specify your own voltage divider ratios and many other parameters. - Franc Zabkar -- Please remove one 'i' from my address when replying by email. |
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