I need to repair pcb which is of a hitachi drive and i have attached the picture below can someone tell me what is the problem in most of the cases when there is no power in hdd . Like which of the components are bad .




Thanks .
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Rameez check your MSN I sent you the schematic.
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salam alekm

i thisnk best thing in this cas is tracing 5 and 12 volt to see where it disappear in the pcb
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thanks for reply but tracing the voltage seems to be a very time taking process . Like in maxtor drives there are two points where u can measure the
3.3v and 5v if there is any problem with that u can change the component corresponding to it , is there any point on IBM like this .
Reply:
salam alekm

i need to know where these 2 points in maxtor
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Heres the main voltages on a working IC35L040AVER07-0. Seems to have same PCB. Try cold spray, or fingers to see if 90G2018 gets warm or hot, and check voltages with the pinout I PM'd you. If 90G gets warm for a few seconds, then goes cold it's probably the problem. You should feel Q1, Q2, & Q3 get warm but not hot. If they stay cold check the voltage at pins also.

Reply:
salam alekm

i want maxtor pcb main faults please
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These are the two points :


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if any one has any other useful info please share .

Thanks .
Reply:
salam alekm
and how to repair these errors in these points?
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Hello,

first: the 5V test point shown on the picture is -5V in reality. Not that much of a difference

3.3V: if not present, probably the L7250E motor combo is damaged, but there is also a fusing resistor near R504 (on calypso III boards), this can be broken too, but mostly it is broken only after a power surge on the 5V line. Can be caused by the transistor (Q501) damage too, but I have never seen such case.
-5V: if not present, the L7250E or the FDFS2P102 (W503 on some boards) can be burnt. But be careful, if it is burnt there should be a cause for that, for example a preamp damage inside the HDA.

BTW I am always telling anybody who wants to touch a PCB should have at least some basic education of electronics, preferably an experienced technician or engineer...
Just to recognize the parts and figure out their function at least.

regards,
pepe
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