Author Topic: Williams System 11c CPU LEDs - all 3 are out????  (Read 408 times)

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Offline beaky

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Re: Williams System 11c CPU LEDs - all 3 are out????
« on: November 29, 2009, 07:04:15 PM »
Assuming the 3 leds are dead (for whatever reason) does the machine have any life?


Forgot to add.....when you measure the voltages on the chips etc, do you have the negative lead on a common ground point somewhere on the board?

It's preferable to measure the volts (and ground) on the chip pins to prove 5v/0v is actually arriving at the chip.
There can always been a broken ground-track between the common board ground and the chip-pin....

May be go re-measure your chips?

MM.
correct MM
that is why i have asked him to check the resistance from the ground strap to TP1 and then voltage from TP1 to TP2.
after he confirms that there is a ground to tp1 then i was going to ask him to check the voltage on pin 1 to pin 20 on U10, U38, U41, U42, U51, U54

you are right on track MM  ^^^
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