I usually power the board up without any proc. The i grab a voltmeter and measur either on the backside on the big caps if any Vcore like voltage is there. Or i put on probe to a ground point (e.g. a circle around a screw ) and put the other probe to the legs of those rectangular transistors or diodes. Usually on of those pins is on 5v or 12v, one is on 10v and one is on Vcore. Se atachement for an example. The layout of a Vcore circuit can differ, but they are always the same basic shematic. There are usually on every board an inputinductor, the input caps and hte o/p section. It is not hard to fifure it out.
PS: mesuring the o/p for short with 5v or 12v line to ground can be misleading. On any of my recapped boards, i have always measured a short with my ohmmeter (may be due to the small supply current of the DVM and the high capcitance of the caps). But all of them are working fine.
That board doesn't even have synchronous rectification!
Yeah, the VRM layout looks similar to my K7SEM (M810*) which once ate up a nice Thoroughbred B due to bad caps. If you've lost 8 CPUs this year, check the PSUs first for bad caps.
I usually power the board up without any proc. The i grab a voltmeter and measur either on the backside on the big caps if any Vcore like voltage is there. Or i put on probe to a ground point (e.g. a circle around a screw ) and put the other probe to the legs of those rectangular transistors or diodes. Usually on of those pins is on 5v or 12v, one is on 10v and one is on Vcore. Se atachement for an example. The layout of a Vcore circuit can differ, but they are always the same basic shematic. There are usually on every board an inputinductor, the input caps and hte o/p section. It is not hard to fifure it out.
PS: mesuring the o/p for short with 5v or 12v line to ground can be misleading. On any of my recapped boards, i have always measured a short with my ohmmeter (may be due to the small supply current of the DVM and the high capcitance of the caps). But all of them are working fine.
Great,
Now I need to know exactly how this is done. My background is computer hardware and IT not electronics. I suppose I'm coming at the field of mainboard repair from a disadvantage.
When testing a board in unknown state, I do this:
1. Check (by using ohm meter) that there is no short between 12V, 5V, 3.3V and GND
2. If all caps are present and none of them is bulged, power it on without anything installed and check DIMM and CPU voltages
Hi guys,
Can anyone tell me how to know if a board will be a CPU killer before I pop in a CPU. To this point I've just chalked it up to cost of business and I use the cheapest athlon socket A chip I can find. I've probably fried about 8 in the last year and I would love to stop frying them.
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