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(SOLVED?) Hitachi HDS728040PLA320 repair - missing R3, no life

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First post, by kotel

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Hi

While back I got an Hitachi deskstar HDS728040PLA320 drive. Powered it on but was greeting with nothing. No spin, no beeps. Doing a visual inspection I found an missing capacitor near motor controller and an R3 resistor which almost broke off (R3 is near R63). While trying to resolder that R3 I accidentally lost it. There aren't any shorts on 3.3/5/12v lines.
So now I the question is, what is the resistance of R3? It was the no markings type so I can't go on google and find a picture of the PCB. Buying a new board/drive isn't an option.

Last edited by kotel on 2024-12-15, 09:02. Edited 1 time in total.

"Sent on a mission, to protect the last treasures. Through struggle and strife we can see the light. Even if our mission is partially complete, Our efforts are not in vain.
Let that be our legacy."
-Stronghold 5-5

Reply 1 of 3, by MikeSG

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If you can trace the circuit with R3 back to an IC, there may be a datasheet with resistors specified.

Or if R3 goes to power/ground, and it's not connected to a Voltage Regulator, you could try guessing the value starting at 100k, then 10k, 5k...

If you want to post photos, maybe people here can estimate what the values are.

Reply 2 of 3, by kotel

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After replacing the missing cap the drive spins up, although it doesn't complete seek test.
Traced the R3 to be a bridge between one of the head pins and main IC. Replaced it with an 4k7 resistor (the same as the closest one) but still no go.

After some time the drive finally did the seek test, although it couldn't finish it. The heads are clicking. Opened it up and no surprises. Head still intact. I am not sure whenever it is the resistor thats the problem or bad heads/platter/FW cause board alone isn't detected. It just hangs on detecting drives.

"Sent on a mission, to protect the last treasures. Through struggle and strife we can see the light. Even if our mission is partially complete, Our efforts are not in vain.
Let that be our legacy."
-Stronghold 5-5

Reply 3 of 3, by kotel

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Here are the photos. Do note the original resistor which was near it broke off in the picture.

"Sent on a mission, to protect the last treasures. Through struggle and strife we can see the light. Even if our mission is partially complete, Our efforts are not in vain.
Let that be our legacy."
-Stronghold 5-5

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