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 Post subject: Hitachi HDS721010CLA332 problem
PostPosted: October 29th, 2012, 6:26 
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Joined: October 29th, 2012, 5:56
Posts: 3
Location: Boston
Had hard drive in enclosure when light blinked several times and drive stopped spinning.

Tried to get replacement PCB. With new PCB drive spins, but computer doesn't see it.
Made some checks on dead PCB with multimeter. 12V TVS diode seems fine, but 5V doesn't show connection in any direction (and obviously not shorted).
I'm not sure that I'll be able to accurately move ROM chip to the new PCB.
Any ideas what else to check on old PCB?
Any not expensive place around Boston that can help me with moving ROM chip from one PCB to another?

Thanks.


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 Post subject: Re: Hitachi HDS721010CLA332 problem
PostPosted: October 29th, 2012, 6:35 
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Joined: September 30th, 2005, 7:33
Posts: 849
ostapru wrote:
Any ideas what else to check on old PCB?

Thanks.

Burn zero Ohm resistors close to TVS diodes.


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 Post subject: Re: Hitachi HDS721010CLA332 problem
PostPosted: October 30th, 2012, 4:39 
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Joined: October 29th, 2012, 5:56
Posts: 3
Location: Boston
BGman wrote:
ostapru wrote:
Any ideas what else to check on old PCB?

Thanks.

Burn zero Ohm resistors close to TVS diodes.


Do you mean R470 or R100 resistors?
On my board I don't have 0 marked resistors. All Rxxx resistors test fine (below 1ohm).
I have PCB like this: http://www.ebay.com/itm/HITACHI-HDS7210 ... 27cb231998
There are 2 elements (black 3 pin) close to spindle motor connector marked XY and XZ. Are they bipolar transistors or something else?

Thanks


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 Post subject: Re: Hitachi HDS721010CLA332 problem
PostPosted: November 1st, 2012, 6:13 
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Joined: September 8th, 2009, 18:21
Posts: 16963
Location: Australia
I believe that the two uppermost coils form part of a Cuk converter that supplies -5V to the preamp. IIRC, one coil should measure +5V, and the other should measure -5V.

The bottom two coils are probably part of the Vcore and Vio supplies for the MCU, SDRAM, and flash memory.

I could be wrong about the coils, but your measurements should shine some light upon their functions.

As for XY and XZ, they look like a complementary PNP/NPN pair of bipolar transistors (2SB1714 / 2SD2679), but I'm not certain about this:
http://www.s-manuals.com/smd-files/pdf/2/2sb1714_r.pdf
http://www.s-manuals.com/smd-files/pdf/2/2sd2679_r.pdf

Be careful when making your measurements. You must not damage the 25FU206 IC.

As for transferring this chip, your local TV/AV repairer should be able to handle it for you.

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