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#11
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Computer won't boot up - mobo?
CBFalconer wrote:
Pete Zahut wrote: kony wrote: ... snip ... Possibly a case standoff installed where there shouldn't be one, or something else causing a short? Just grabbing at straws, possibly the board has a broken solder joint(s) or cracks in it and the different orientation or not being screwed down has caused these broken part(s) of a circuit to temporarily be continuous again. You could well be right Kony, I'll have to see what happens when I put everything back in the case again. It's now been running a burn-in program for the last 12 hours without any problems so I'll take this opportunity to say thanks very much to all who replied and offered help - much appreciated. No. First examine (with great care) all the areas where standoffs touch the mother board, and examine the mounting screws too. They may need insulating washers. Good advice Chuck and I was going to do that anyway. I couldn't see anything obvious but, working on the premise that insulating washers would do no harm, I fitted them anyway and all is now well. |
#12
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Computer won't boot up - mobo?
"Pete Zahut" dont@bother wrote in message
... CBFalconer wrote: Pete Zahut wrote: kony wrote: ... snip ... Possibly a case standoff installed where there shouldn't be one, or something else causing a short? Just grabbing at straws, possibly the board has a broken solder joint(s) or cracks in it and the different orientation or not being screwed down has caused these broken part(s) of a circuit to temporarily be continuous again. You could well be right Kony, I'll have to see what happens when I put everything back in the case again. It's now been running a burn-in program for the last 12 hours without any problems so I'll take this opportunity to say thanks very much to all who replied and offered help - much appreciated. No. First examine (with great care) all the areas where standoffs touch the mother board, and examine the mounting screws too. They may need insulating washers. Good advice Chuck and I was going to do that anyway. I couldn't see anything obvious but, working on the premise that insulating washers would do no harm, I fitted them anyway and all is now well. It may not apply here. I did run across one motherboard a few years ago that required chassis grounding via a screw through one standoff to the PC chassis. I was using just stand-offs. PC would do nothing until I found that ground requirement. -- Dave CDOs are how we got here. A modified version, new taxes in the future, is how Congress will get us out? |
#13
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Computer won't boot up - mobo?
Lil' Dave wrote:
It may not apply here. I did run across one motherboard a few years ago that required chassis grounding via a screw through one standoff to the PC chassis. I was using just stand-offs. PC would do nothing until I found that ground requirement. Without proper grounding of the motherboard mounting points, the risk also is transmission of radio frequency interference through any transmissive voids of the enclosure. Also where external cables connect to the motherboard, and are not immediately connected to case ground, there is potential for these leads to further radiate RF acting as external antenna. The issue is not the usage of ground points (I use as many as I can), but the application of screw heads and conductive posts that are too large in comparision to the area allocated for them on the PCB, and hence causing ground shorts to other components. -- Adrian C |
#14
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Computer won't boot up - mobo?
Lil' Dave wrote:
"Pete Zahut" dont@bother wrote in message ... CBFalconer wrote: Pete Zahut wrote: kony wrote: ... snip ... Possibly a case standoff installed where there shouldn't be one, or something else causing a short? Just grabbing at straws, possibly the board has a broken solder joint(s) or cracks in it and the different orientation or not being screwed down has caused these broken part(s) of a circuit to temporarily be continuous again. You could well be right Kony, I'll have to see what happens when I put everything back in the case again. It's now been running a burn-in program for the last 12 hours without any problems so I'll take this opportunity to say thanks very much to all who replied and offered help - much appreciated. No. First examine (with great care) all the areas where standoffs touch the mother board, and examine the mounting screws too. They may need insulating washers. Good advice Chuck and I was going to do that anyway. I couldn't see anything obvious but, working on the premise that insulating washers would do no harm, I fitted them anyway and all is now well. It may not apply here. I did run across one motherboard a few years ago that required chassis grounding via a screw through one standoff to the PC chassis. I was using just stand-offs. PC would do nothing until I found that ground requirement. On the motherboards I've looked at, the mounting holes all have a conductive ring (a so-called "plated hole") and the conductor is connected to ground. That tells you that they want the motherboard to ground to the chassis metal, at the nine mounting points. If they really intended the motherboard to be insulated, they can remove the plated ring and have bare, insulating PCB material. That would easily result in perfect insulation. So the designers have added the copper there, on purpose. Ground is also established via the black ground wires in the main power cable, so there is already a ground connection. Insulating all the standoffs, should still allow the motherboard to operate, since it has the black ground wires from the power supply. The main value of ground points on the bottom of the motherboard, is better control of electromagnetic interference from the PCB. Similarly, there are "spring fingers" on the I/O plate, which press on the metal housings of the I/O stacks. The spring fingers are there to ground the housings, and better control EMI from the I/O area. Paul |
#15
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Computer won't boot up - mobo?
On Fri, 27 Feb 2009 10:53:15 -0000, "Pete Zahut"
dont@bother wrote: CBFalconer wrote: Pete Zahut wrote: kony wrote: ... snip ... Possibly a case standoff installed where there shouldn't be one, or something else causing a short? Just grabbing at straws, possibly the board has a broken solder joint(s) or cracks in it and the different orientation or not being screwed down has caused these broken part(s) of a circuit to temporarily be continuous again. You could well be right Kony, I'll have to see what happens when I put everything back in the case again. It's now been running a burn-in program for the last 12 hours without any problems so I'll take this opportunity to say thanks very much to all who replied and offered help - much appreciated. No. First examine (with great care) all the areas where standoffs touch the mother board, and examine the mounting screws too. They may need insulating washers. Good advice Chuck and I was going to do that anyway. I couldn't see anything obvious but, working on the premise that insulating washers would do no harm, I fitted them anyway and all is now well. Insulating washers should not be needed, as Paul noted a board is designed to be grounded through the standoffs. What I'd meant in my prior remark about standoffs is that possibly there is a standoff installed in the case that shouldn't be there at all, with no corresponding hole in the motherboard through which to secure it. One common location where there might be such a standoff is on the left-hand side, second hole up from the bottom of the case (if it's a full sized ATX, not mATX board). |
#16
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Computer won't boot up - mobo?
"Paul" wrote in message
... Lil' Dave wrote: "Pete Zahut" dont@bother wrote in message ... CBFalconer wrote: Pete Zahut wrote: kony wrote: ... snip ... Possibly a case standoff installed where there shouldn't be one, or something else causing a short? Just grabbing at straws, possibly the board has a broken solder joint(s) or cracks in it and the different orientation or not being screwed down has caused these broken part(s) of a circuit to temporarily be continuous again. You could well be right Kony, I'll have to see what happens when I put everything back in the case again. It's now been running a burn-in program for the last 12 hours without any problems so I'll take this opportunity to say thanks very much to all who replied and offered help - much appreciated. No. First examine (with great care) all the areas where standoffs touch the mother board, and examine the mounting screws too. They may need insulating washers. Good advice Chuck and I was going to do that anyway. I couldn't see anything obvious but, working on the premise that insulating washers would do no harm, I fitted them anyway and all is now well. It may not apply here. I did run across one motherboard a few years ago that required chassis grounding via a screw through one standoff to the PC chassis. I was using just stand-offs. PC would do nothing until I found that ground requirement. On the motherboards I've looked at, the mounting holes all have a conductive ring (a so-called "plated hole") and the conductor is connected to ground. That tells you that they want the motherboard to ground to the chassis metal, at the nine mounting points. Imagine seeing this about 11 yeara ago for the first time after using strictly standoffs for so many PC builds? No information in installation. Trial and error. You get my drift... -- Dave CDOs are how we got here. A modified version, new taxes in the future, is how Congress will get us out? |
#17
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Computer won't boot up - mobo?
"Pete Zahut" wrote:
Kony/Anna/Peter - not measured voltages because (at that time anyway) the motherboard was still in the case and it was very difficult to get the probes into the connector. Acquire a short length of "twisted pair" solid telco cable (22 or 24ga). Strip the outer sheath to expose the wires inside, and cut two six-inch lengths. Strip a half inch off of each end, and curl one end up. Grab the curled end in the alligator clips at the end of your multimeter leads, and the other end will fit nicely into the PSU molex connectors (or most any other little connector). because faults don't just fix themselves - but it has. You'd be surprised how many times things get fixed by just taking them apart and looking at them. Sometimes I think they get lonely and break themselves just to see if anyone still cares enough to poke around inside of them. Jon |
#18
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Computer won't boot up - mobo?
"Jon Danniken" wrote in message ... "Pete Zahut" wrote: Kony/Anna/Peter - not measured voltages because (at that time anyway) the motherboard was still in the case and it was very difficult to get the probes into the connector. Snipped some because faults don't just fix themselves - but it has. You'd be surprised how many times things get fixed by just taking them apart and looking at them. Sometimes I think they get lonely and break themselves just to see if anyone still cares enough to poke around inside of them. Jon That made me smile Jon. And there`s a lot of truth in there somewhere. % ) |
#19
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Computer won't boot up - mobo?
Jon Danniken wrote:
"Pete Zahut" wrote: Kony/Anna/Peter - not measured voltages because (at that time anyway) the motherboard was still in the case and it was very difficult to get the probes into the connector. Acquire a short length of "twisted pair" solid telco cable (22 or 24ga). Strip the outer sheath to expose the wires inside, and cut two six-inch lengths. Strip a half inch off of each end, and curl one end up. Grab the curled end in the alligator clips at the end of your multimeter leads, and the other end will fit nicely into the PSU molex connectors (or most any other little connector). because faults don't just fix themselves - but it has. You'd be surprised how many times things get fixed by just taking them apart and looking at them. Sometimes I think they get lonely and break themselves just to see if anyone still cares enough to poke around inside of them. I had a networked printer twenty years ago that was bipolar. It would work like a fiend for three weeks in a row, but would inevitably fall into a funk. Fortunately, a few minutes of attention--pushing buttons, unplugging cables, etc.--would bring it around again. |
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