LoboX":1fnnhnwi said:
[post]7371[/post] Wow seems i have the same problem with a hdd i got yesterday. Hmmm the read short pins is the thing i need to figure out where is it.
Here's how to figure it out:
1. Take or find a high-res picture of the PCB, both sides
2. Locate the two paired traces that lead from the MCU to the HDA connector
3. Measure the voltage-to-ground (screw hole) of one trace from each pair (with PCB bare, of course).
The pair that has 1.8v - 2.5v to ground will be the write channel traces; the other pair should be near zero volts to ground and will be the read channel.
4. Locate on the component side, the vias that connect each of the paired traces to the bare side of the PCB
5. Locate those vias on the bare side of the PCB. The pair that belonged to the read channel is the pair to short.
To help locate the vias on the bare side, I flip and rotate the image of the component side so it corresponds to the image of the bare side, as shown below. The vias in the bare-side image now are in the same relative positions as in the component side image, making locating the vias easier. If I'm not mistaken,
the pair furthest from the two screw holes are the read channel.
Component side of the PCB, flipped and rotated
Bare side of the PCB