Fzabkar, excuse me but I was wrong.
Firstly, because in the resistance scale I selected 200 ohms all the times and that's the reason why it was always saying "OL".
And also I wrongly selected the diode scale for measurements.
You are right, my data were wrong.
For example, I have been able to verify that fortunately there is no continuity between HDA pin #1 and HDA pin #4.
I have taken all the measurements again and they are next:
[Note: I have used a better multimeter than before and now the resistance of the new multimeter is only 0.5 ohms (instead of 1.3 ohms)].
1) Pin #1 of J1 is Ground (confirmed).
Multimeter in Ohm scale (selecting 200 ohms):
If I place the tip of the black probe in a screen hole and the tip of the red probe in pad #1 of J1, then there is a resistance of 0.5 ohms. But since the multimeter resistance is 0.5 ohms. Therefore the real resistance of pad #1 of J1 is 0 ohms.
2) Pin #4 of J1 is -5 V: confirmed (but it is working badly)
Multimeter in Ohm scale (selecting 200 ohms):
If I place the tip of the black probe in anode of D2 and the tip of the red probe in pad #4 of J1: I get a resistance of 0.5 ohms. But since the multimeter resistance is 0.5 ohms. Therefore the real resistance is 0 ohms.
3) Anode of diode D2 is working badly, it never gives a reading of -5V
Multimeter in DCV scale (selecting 20 V):
If I place the tip of the black probe in a screw hole as ground and the tip of the red probe in the anode of D2, then I do not get -5V but a reading of 3.24V. (I do NOT get a reading of -5 V, not even just after plugging the PCB into the SATA power conector of the PSU. I always get 3.24 V or around. In fact, after a few minutes, the anode of D2 gives no voltage).
4) Pin #4 of J1 has the same wrong voltage as anode of diode D2
Multimeter in DCV scale (selecting 20 V):
If I place the tip of the black probe in a screw hole as ground and the the tip of red probe in pad #4 of J1, then I do not get -5V but a reading of 3.24V. (I have taken quite a lot of readings and it always says the same).
5) Pin #6 of J1 is +5 V: confirmed.
Multimeter in Ohm scale (selecting 200 ohms):
If I place the tip of the black probe in pad #6 of J1 and the tip of the red probe in pin #8 of the SATA Power connector: I get a resistance of 0.5 ohms. But since the multimeter resistance is 0.5 ohms. Therefore the real resistance is 0 ohms.
Multimeter in DCV scale (selecting 20 V):
If I place the tip of the black probe in a screw hole as ground and the tip of the red probe in pin #6 of J1, I get a reading of 5.09 V.
Now I am going to give you the measurements I have taken to the preamp:
fzabkar wrote:
I expect that the anode of D2 connects to HDA pad #4. If so, then this is the -5V supply for the preamp.
Multimeter in continuity scale:
If I place the tip of the black probe in anode of D2 and the tip of the red probe in HDA pin #4: there is NO continuity. It does not beep at all.
Multimeter in Ohm scale (selecting 200 ohms or 2000 ohms or 20 k-ohms):
If I place the tip of the black probe in anode of D2 and the tip of the red probe in HDA pin #4: I get "OL". (I always get "OL" even if I select 20 k-ohms).
fzabkar wrote:
OK, I think pin #6 connects to D2
Multimeter in continuity scale:
If I place the tip of the black probe in anode of D2 and the tip of the red probe in HDA pin #6: there is NO continuity. It does not beep at all.
fzabkar wrote:
I would also measure the resistances of the preamp by testing for shorts between pin #1 (Ground ?) and pins #4 and #6
1) Resistance between HDA pin #1 and HDA pin #4:
Multimeter in Ohm scale (selecting 20 k-ohms):
If I place the tip of the black probe in HDA pin #1 and the tip of the red probe in HDA pin #4: I get a reading of 6.80 k-ohms (i.e., 6,800 ohms).
2) Resistance between pad #1 of J1 and pad #4 of J1:
Multimeter in Ohm scale (selecting 20 k-ohms):
If I place the tip of the black probe in pad #1 of J1 and the tip of the red probe in pad #4 of J1: I get a reading of 13.49 k-ohms (i.e., 13,490 ohms).
3) Resistance between HDA pin #1 and HDA pin #6:
Multimeter in Ohm scale (selecting 20 k-ohms):
If I place the tip of the black probe in HDA pin #1 and the tip of the red probe in HDA pin #6: I get a reading of 12.58 k-ohms (i.e., 12,580 ohms).
4) Resistance between pad #1 of J1 and pad #6 of J1:
Multimeter in Ohm scale (selecting 200 k-ohms):
If I place the tip of the black probe in pad #1 of J1 and the tip of the red probe in pad #6 of J1: I get a reading of 47.4 k-ohms (i.e., 47,400 ohms).
Again, regarding resistor R47 (theoretically R100, ie. 0.10 ohms), I have measured it again.
And I got 1,014 ohms (one thousand and forteen ohms!).
I have taken several measurements and I got the same result. Therefore it is clearly damaged.
Also, I get some strange readings in pin #8 of J1:
Multimeter in DCV scale (selecting 20 V)
If I place the tip of the black probe in a screw hole as ground and the tip of the red probe in pin #8 of J1, I get 2.40 V. I have done quite a lot of tests and always it gives me 2.40 V or around.
Is this voltage correct for pin #8 of J1?
In conclusion, it seems that the main problem is the anode of diode D2. Because it is giving an incorrect supply of 3.24 V. And for this reason pin #4 of J1 has this wrong voltage.
Fzabkar, excuse me for my errors.
And many, many thanks for your patience and help.