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#1
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No POST only FF alarm on boot
I've been running an Epox MVP3C2 for a while, then I damaged a couple of SMD
componets getting the clip off the HSF. The board has been repaired (I am in the electronics industry), and *should* be OK. Problem is the FF alarm sounds immediately it starts to boot. I suspected it was that I had previously set in the *BIOS* for the alarm to sound if the CPU fan was under a limit (if that's possible), whereas this time I am using a fan straight off the PSU (which is working). To trick the alarm I have fitted a couple of separate CPU fans to the 3-pin connection for the CPU fan (also also for the chassis fan), but noticed neither would turn at all besides a flicker when the on-off switch is pressed. Does anyone know if the lack of power to the mobo fan connections is the fault cause of the FF alarm - or the alarm is doing the opposite and cutting the power to the mobo? What other causes for a lack of power to the 3-pin connectors - is there a fuse on the board anywhere? Besides if the PSU or mobo connectors are faulty... TIA Keith |
#2
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On Tue, 3 Feb 2004 12:20:38 +0200, "John Smith"
wrote: I've been running an Epox MVP3C2 for a while, then I damaged a couple of SMD componets getting the clip off the HSF. The board has been repaired (I am in the electronics industry), and *should* be OK. Problem is the FF alarm sounds immediately it starts to boot. I suspected it was that I had previously set in the *BIOS* for the alarm to sound if the CPU fan was under a limit (if that's possible), whereas this time I am using a fan straight off the PSU (which is working). To trick the alarm I have fitted a couple of separate CPU fans to the 3-pin connection for the CPU fan (also also for the chassis fan), but noticed neither would turn at all besides a flicker when the on-off switch is pressed. Does anyone know if the lack of power to the mobo fan connections is the fault cause of the FF alarm - or the alarm is doing the opposite and cutting the power to the mobo? What other causes for a lack of power to the 3-pin connectors - is there a fuse on the board anywhere? Besides if the PSU or mobo connectors are faulty... TIA Keith The third wire is a speed sensor, which the motherboard uses to detect a fan not moving. You can make (or buy) an adapter that splits the fan cable so that power comes from a PSU connector, and the speed sensor connects to the motherboard fan connector. Sold for people that want to put big, high current fans on CPU heatsinks. There is probably an SMD fuse or resistor that acts like a fuse in the 12v line for the fans on the motherboard. No telling where it actually is located. JT |
#3
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"JT" datacare@www wrote in message s.com... On Tue, 3 Feb 2004 12:20:38 +0200, "John Smith" wrote: I've been running an Epox MVP3C2 for a while, then I damaged a couple of SMD componets getting the clip off the HSF. The board has been repaired (I am in the electronics industry), and *should* be OK. Problem is the FF alarm sounds immediately it starts to boot. I suspected it was that I had previously set in the *BIOS* for the alarm to sound if the CPU fan was under a limit (if that's possible), whereas this time I am using a fan straight off the PSU (which is working). To trick the alarm I have fitted a couple of separate CPU fans to the 3-pin connection for the CPU fan (also also for the chassis fan), but noticed neither would turn at all besides a flicker when the on-off switch is pressed. Does anyone know if the lack of power to the mobo fan connections is the fault cause of the FF alarm - or the alarm is doing the opposite and cutting the power to the mobo? What other causes for a lack of power to the 3-pin connectors - is there a fuse on the board anywhere? Besides if the PSU or mobo connectors are faulty... TIA Keith The third wire is a speed sensor, which the motherboard uses to detect a fan not moving. You can make (or buy) an adapter that splits the fan cable so that power comes from a PSU connector, and the speed sensor connects to the motherboard fan connector. Sold for people that want to put big, high current fans on CPU heatsinks. There is probably an SMD fuse or resistor that acts like a fuse in the 12v line for the fans on the motherboard. No telling where it actually is located. JT Thanks JT, yep we're thinking along the same lines now - the one damaged resistor was replaced with another only a few ohms different but it may be the culprit. Hopefully that and not PCB damage - WTF Epox had to put the t/h capacitors on the same line as the lugs for the cpu clip I don't know, hence I "tried" pushing the clip off to the side with a flat blade screwdriver :-o BTW, last night I had the mobo set-up with just (Cyrix) cpu, DIMM and AGP card and a different PSU - AGP card's fan worked and the cpu warmed-up, so there is power on the mobo elsewhere. Keith |
#4
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On Wed, 4 Feb 2004 16:22:31 +0200, "John Smith"
wrote: Thanks JT, yep we're thinking along the same lines now - the one damaged resistor was replaced with another only a few ohms different but it may be the culprit. Hopefully that and not PCB damage - WTF Epox had to put the t/h capacitors on the same line as the lugs for the cpu clip I don't know, hence I "tried" pushing the clip off to the side with a flat blade screwdriver :-o BTW, last night I had the mobo set-up with just (Cyrix) cpu, DIMM and AGP card and a different PSU - AGP card's fan worked and the cpu warmed-up, so there is power on the mobo elsewhere. Keith A few ohms in the 12v line to the fans would be major difference. The little fuse/resistor is normally 1ohm or less. 12v line, 300ma per fan. Only want a very small voltage drop. Other resistors in that area are also somewhat critical. Some of them are terminating resistors and need to be very close to the original value. A few ohms might different might not work. If you put in a resistor with different value, that could very well be a problem. JT |
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