Samsung HD154UI circuit board repair

[fzabkar]

Yes, that's correct.

[fzabkar]

I've had a look at the power components on your bridge PCB. There appear to be 4 DC-DC converters. The main one is IC19 (SC4519). It steps down the incoming +12V supply to +5V. The +12V supply appears to be fed directly to the HDD. The specs for IC19 state that it can tolerate an absolute maximum voltage of 24V, so if you have subjected your enclosure to a 19V laptop supply, then it will most probably have survived unscathed.

I can't see the markings on IC20, but IC2 and IC10 could be 3.3V and 1.95V regulators. They are probably derived from the +5V supply. In short, it appears that all the components derive their power from IC19, either directly or indirectly, so if IC19 survived the overvoltage, then the other components will also have survived.

You could test the bridge PCB by powering it up on its own and connecting it to a USB port on your PC. Then you could use UVCView or USBDeview to test whether Windows can see it.

http://www.nirsoft.net/utils/usb_devices_view.html
http://download.microsoft.com/download/ ... 436b-9281- 92cdfeae4b45/UVCView.x64.exe
http://www.users.on.net/~fzabkar/USB_ID ... ew.x86.exe

If the bridge PCB is detected by Windows, then it will most probably be OK. However, I would backup your drive inside the PC before reconnecting it to your enclosure.

References:

SC4519, Semtech, 600kHz, 3A Step-Down Switching Regulator, 24V abs max, 16V nominal:
http://www.semtech.com/images/datasheet/sc4519.pdf

REG1117, Texas Instruments, LDO Voltage Regulator:
http://www.ti.com.cn/cn/lit/ds/symlink/reg1117.pdf

TSB81BA3D, Texas Instruments, IEEE 1394b THREE-PORT CABLE TRANSCEIVER/ARBITER, 3.3V/1.95V:
http://www.ti.com/lit/ds/symlink/tsb81ba3d.pdf

SST39VF020-70-4C-WHE, Microchip, 4Mbit, 512K x 8, 2.7-3.6V, flash memory:
http://ww1.microchip.com/downloads/en/D ... 25023A.pdf

Attachments

[EAAo]

When I test the 5v TVS diode the multimeter displays 1 both ways.

When I test the 12v TVS diode it fluctuates and settles on 0.4000 both ways.

[fzabkar]

Remove the 12V diode.