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186
 
Group: Forum Members
Last Login: 23/11/2008 23:24:37
Posts: 3,
Visits: 7
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The unit, which was presumably a “Media Centre” had been written off, and its “TV” card and remote control removed. The retention frame for the microprocessor cooler was broken. Any testing would require use of three hands or more.
I began by totally dis-assembling in order to examine the board carefully, but could see no visual problem. When I tried to switch on, there was evidence of “something happening”, a vague noise and an illuminated (flashing) LED on the back, but no start-up.
I tried the PSU in another shuttle (spacewalker) and found it would not power that up. I dismantled the power supply and replaced seven bulging capacitors, and it will now fire up the “spacewalker” correctly, but not the MS 6760.
I connected a known good standard PSU and tried again, but it would not start up. Because the “on” button was on an unusual front panel, I located the normal “pwr” pins and tried shorting with a screwdriver in time honoured fashion. Still nothing. I don't know why, but I then tried shorting the green pin14 “PS-on” connector from the PSU. The flashing LED went off, and the vague noise subsided. Pressing the “on” button brought forth life! A 4-second press would then give typical shut down. Similarly, the “pwr” pins could be shorted for start and shut down.
If the mains power is removed from PSU, only initial brief shorting of pin 14 will permit normal operation. A permanent short would allow start up, but no shut down was possible.
Clearly I could fit a “reset” button on the back, for use after a mains shut down, but there must be a more elegant method. I need more information regarding the typical motherboard circuitry for pin 14, or maybe a simple “work around”.
I have never (knowingly) met this fault before with a PC.
Any suggestions?
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