| Electronics > Repair |
| Can someone help identify these caps? |
| << < (5/8) > >> |
| fzabkar:
The preamp on the headstack needs two supply voltages. Typically these were +5V and -5V. The former was derived directly form the 5V input, usually via a low pass LC filter. I don't know if the newer HGST drives down-regulate the +5V supply. If not, they would be exposed to any noise or dips on this rail. |
| phlegeton:
That is interesting, is that easy to determine? |
| fzabkar:
--- Quote from: phlegeton on August 09, 2024, 06:11:47 pm ---That is interesting, is that easy to determine? --- End quote --- Yes. Remove the PCB, upload a photo, and I'll show you where to test. |
| phlegeton:
See attached photo. Hope it's sharp enough. |
| fzabkar:
Your PCB has two stages of protection. The first level has two TVS diodes and two smt fuses. The second level has an IC that incorporates a Vcore regulator plus 5V and 12V e-fuses. https://www.hddoracle.com/viewtopic.php?p=22339#p22339 I have marked what I think are the preamp supply test points on the HDA connector. Measure those voltages. I suspect that the negative supply will be -3V. If the positive supply is +5V, then power down and test for continuity with the 5V pins at the SATA power connector, and the +5V e-fuse. |
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