PCB Help TVS Chip

[LoboX]

PCB Help TVS Chip

Postby LoboX » Fri Sep 06, 2013 1:20 pm
Hi i am trying to fix a WD hdd, if i plug the power, the drive doesn't do jack, so first place to look TVS CHIP.

1) If i have faulty TVs chips, and i try to test the voltage of both chips, and i get a voltage reading that means the chips are working? Do i still need to remove them?
2) If i remove the 2 chips and still the hdd doesn't turn on, what else could be the problem?
3) I know i can use another PCB to test hdd to see if it turns on, what can i do if the hdd that i have the connection of the spindle doesn't match the hdd i am trying to fix anyway around this.

Any tips would be great just learning a couple of things here, Data is not important i am just curious to see how this works.

Thanks

Attachments

TVs Chip

[fzabkar]

Hi i am trying to fix a WD hdd, if i plug the power, the drive doesn't do jack, so first place to look TVS CHIP.

See http://www.users.on.net/~fzabkar/HDD/TVS_diode_FAQ.html

... and http://www.users.on.net/~fzabkar/HDD/bi ... diodes.jpg

1) If i have faulty TVs chips, and i try to test the voltage of both chips, and i get a voltage reading that means the chips are working? Do i still need to remove them?

Why would you remove something that is working?

2) If i remove the 2 chips and still the hdd doesn't turn on, what else could be the problem?

You would need to make some additional measurements.

3) I know i can use another PCB to test hdd to see if it turns on, what can i do if the hdd that i have the connection of the spindle doesn't match the hdd i am trying to fix anyway around this.

The 88i6745 MCU contains embedded data that would need to be transferred to your donor. Alternatively, you would need to retrieve these data from the System Area in a reserved section on the platters.

[LoboX]

Thank you for that link and picture i understand better now. One thing tho.

1)You would need to make some additional measurements. If I removed the diodes and i still have the problem, what else can i verify before i purchase a donor PCB.

Thank you for your help really appreciated

[fzabkar]

I would measure the voltages of the onboard supplies. That would help me understand the nature of the fault. My next step would depend on the results.

So what have you found so far?

[LoboX]

Hi, OK i have found another triangle PCB, i have test the bad hdd with the good PCB to see if i get power, and i did the bad hdd turn on, and then turn off i know that is whats going to happen cause of the FW. Now my main goal is trying to fix the Bad PCB, to see why is not giving power to my hdd.

[LoboX]

Hi i am testing with the multimeter, and found something odd, i am testing the connector that gives power to the spindle and for some reason in the Good PCB it beeps and on the Bad PCB it doesn't, maybe this is my problem?

The bad PCB Is not receiving power there?

Attachments

Bad & Good PCB

[LoboX]

OK now i am confused i took another hdd Samsung and i was checking the same connection i check in the last pic i posted, it didn't beep, but it turned ON the Samsung drive. Hmmm

[fzabkar]

Did you measure those test points with the PCB mounted on the drive?

What measurements did you get in step #1?

[LoboX]

Did you measure those test points with the PCB mounted on the drive?

What measurements did you get in step #1?

Hi again and thank you for trying to help me, OK the test i have been doing are without the PCB mounted on the hdd, i just took the PCB from the hdd and starting testing the points on the PCB. I have been reading the FAQ about diodes and none went to 0.0, so i guess they are OK one thing tho the TVS Chips are diodes right? what about the other small electronic pieces ex:R67 or R64 are those diodes too?

[LoboX]

OK i have posted a pic of the bad PCB with the TVS Chips "Diodes" removed, still same problem no power one thing are those mark electronic little chips are diodes too?.

Thank you.

Attachments

Diodes?

[fzabkar]

Sorry, I don't think I can help you. I don't mean to offend, but your questions suggest that you may be way out of your depth.

[LoboX]

No problem man, if you cant help that's , too bad yeah sorry about my questions i was just curious to know, not offended bro trust me, I am learning and i know it will take time, I really appreciate the help that u have giving me already

[LarrySabo]

Here's a primer that might help get you started. Perhaps start at the beginning.

[LoboX]

Wow nice link, thank you LarrySabo i will start reading