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Question : Problem: eMachines motherboard replacements driving me nuts
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I currently have two eMachines PCs a T2826 and T2865. They are nearly identical except for hard drive capacity. The motherboard is made by FIC and is model AU31. Both machines behaved like the motherboard was bad: system wont power on, no video, no POST beeps, power supply tests OK, etc.
My first attempt to repair was to buy a new BIOSTAR M7NCG 400 nForce2 as a replacement. This board was picked because it uses the same chipset. After carefully installing it ran for all of five seconds. Then it would power up at all. Further investigation on newegg and other sites turned up several mentions of DOA boards.
Then I found a seller on ebay with the OEM motherboard with a 90 day warranty. Claimed that they were new replacement boards that they didnt need. I bought one and installed it. A few seconds after powerup I heard a click. I also smelled that electronics burning smell you may be familiar with. Subsequent attempts to power it up were successful. Note that subsequent power ups came as soon as the power supply was plugged in, no need to press the switch. I believe that was one of the original symptoms on this PC. I did not see any video output that was readable, it was just a bunch of jittery blue streaks. I tried resetting CMOS
Im a little confused about the FSB settings. The new OEM board has a sticker that says 400 MHz FSB. The two original boards dont have this sticker. The chip for each PC is an AMD Athlon XP 2800+. The PDF version of the manual I found online shows a jumper that switches between 133/166 MHz FSB, which is the default, and 100/133 MHz FSB. Heres a quote from the PDF manual:
Processor Supported
Supports 462-pin SocketA for AMD Athlon XP and Duron processors with
200/266/333MHz Front Side Bus
- Athlon XP (1500+ to 2800+) @ 266/333MHz Front Side Bus,
- Duron (800 to 1.3GHz) @ 200MHz Front Side Bus
Whats Wrong?
Two bad motherboards?
This is my initial reaction. The BIOSTAR motherboard didnt get the best reviews and several reviews mentioned getting DOA boards. Mine didnt even come with an ATX backplate! Not impressed. A board bought on ebay, while from a seller with good feedback, can be suspect. Plus, Ive seen two machines with this board that have gone bad. It seems to me that the odds are high that another has.
Bad processor?
Never really seen that, only once. Dont think that would cause what Im seeing. Carefully installed heat sink with Arctic Silver 5 according to mfg directions.
Bad power supply?
Ive tried two different power supplies. Both new boards Ive started with the stock power supply. Maybe its frying them with over-voltage. That would be a first for me. I tested each with a simple tester and it read OK. Maybe more extensive testing is needed.
Shorts?
Possibly with the BIOSTAR board since its not stock. With the second board Im stumped because its identical to the original and installed the same way.
Pulling my hair out, beating my head against the wall, etc. Got any ideas?
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Answer : Problem: eMachines motherboard replacements driving me nuts
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Hello,
Is the power supply the Emachine power supply?
Emachine power supplies are known to fry the board and the mouse and keyboard when going bad.
Also the Emachine motherboards board does the same thing.
Disconnect the power supply from the board and test the power supply by connecting the green and black wire on the 20 pin connector and checking each color reading.
Each should be close to the following.
Orange +3.3
Blue -12
Red +5
White -5
Purple +5
Yellow +12
Rated (in volts) Acceptable Rating (in volts)
+3.3 +3.0 to 3.44
+5 +4.8 to +5.2
-5 -4.5 to -5.4
-12 -10.8 to -12.9
+12 +11.5 to +12.6
I suspect the power supply toke out the motherboard.
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