GH688,GA628, Standard Electrical Repairs
4/00021-2/FEA 209 544/1.G 54 (112)
Fig. 8.7
• If the resistance is correct, measure the resistance from C600 (fig. 8.2) to marked
side of the resistors of the row (R630-R634, in this case R630, should be ~0
ohms) and from the other side of the resistor to the marked side of the keyboard
pads (~0 ohms).
* If any of the resistances are too high it means that there’s a foil damage in
the circuit board and the board is to be discarded.
* If all of the resistances are correct, check the solderings at D600 pads 1 and
120-128.
* If all of the solderings are correct, replace D600 (class B).
If there are voltage on only some of the pads on a row (for instance on pad 1 and 2
but not on pad 2, 4 or Yes2), there’s a foil damage and the board is to be discarded.
This can be verified through checking the resistance from marked side on a working
pad to marked side of a non-working pad (~0 ohms). The foil damage is often
caused by liquid damage.
If a column or a part of it is faulty, check the solderings of D600 pads 1 and 120-
128.
• If all the solderings are correct, replace D600 (class B).
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