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HDCombo 12v power problem and correction.
HDCombo 12v power problem and correction. –
After sucessfully installed HDCombo for 24 hours, my harddrive is fried...
I found out the drive would not spin up anymore. Then I took it off, powered it on using a good external powersource to check if it is OK - it still would not spin up. In addition, I found out the motor control chip of the HD gets really hot very fast. By then I recognized it is the motor circuit got fried (becuase I have fried *lots* of my harddrives two years ago due to a bad PSU...)
Anyway, I started to doubt it is the HDCombo's problem. So I multimetered it, and confirmed my doubt. The problem of my HDCombo is that when it is turned off, ONLY the 5v power is cut off; the 12v power remains on and cannot be turned off unless you unplug the power supply cord. To make it worse, becuase the 5v output is cut off, there is lighter load, so 12v actually floats to 13.5v...
So, what happened to my harddrive is that, I pluged it into HDCombo 24 hours ago, used it normally for about 3 hours. But for the remaining 21 hours when it is turned ?off?, it is constantly supplied 13.5v on the 12v pole and 0v on the 5v pole. This abnormal powersupply could finally lead to the motor controller to go south...
I suspected it may be an installation error and should be easy to fix. So I took a look at the PCB, however, to my suprise, on the PCB there is nothing to control the 12v power input! It goes straight to the 12v power connector of the HD; the switch on the bach of HDcombo only handles 5v!!!
I believe this is quite easy to fix. Just buy a DPST or DPDT to replace the SPDT switch, and reroute the 12v power via the switch. But this does require some minor soldering work (3 joints).
For everyone who is using HDCombo currently, could you please check if yours does the same thing as mine? I wonder there may be different versions of the PCB and mine just happen to be a buggy one...
For those who is going to use HDCombo, my advice is to also check for this power problem. If it does have the same problem and you are too lazy to fix it, just cut off the power to the adapter everything after use and your HDD will be fine...
Last edited by Chizuna; 03-03-2007 at 03:30 AM.
Yeah, finally got my HDCombo power line fixed! Since I did not notice a version mark on the PCB, I assume everyone have the same board with the power problem. So here you go for those have some free time to kill...
The basic idea is to re-route the 12v power wire via the DP switch, so that when the switch is turn to "off", both 5v and 12v power inputs are cut off from the HDD, preventing the motor control chip and other components to suffer from abnormal power input.
Steps are almost the same as described in my previous post:
(Sorry my old DC does not have micro, can't get you a picture)
Prepare the following things (should be able to collect all of them with one trip to RadioShack):
1. A Double Pole switch (DPST or DPDT)
2. A Soldering iron
3. Some repair solder
4. About 8 inches of 20AWG wire
5. Dielectric tape
6. A small fine file
7. A Multimeter (or just a DC voltmeter)
NOTE: ASCII diagrams are for abstract illustration purpose, and are not drawn to scale!
Step 0, unscrew and disassemble the PS2 until you have just the HDcombo back casing; unscrew the blue PCB, pull it out carefully, to the point when you have clear access to the back of the board.
Step 1, heat up the soldering iron and remove the 12v power connections to the back of the board. (The YELLOW WIRES, both of them)
===|=8 12v (detach old wires)
| : GND
| : 5v
Step 2, cut 1.5inch 20AWG wire, peal both ends. Make a solder joint of 3 ends of wires: both YELLOW WIRES you just detached from the board and the new wire you just cut and prepared.
(new wire) (12v wires)
------------<======== (from power input)
Step 3, cut TWO 2inch 20AWG wires, peal ends. Solder on one end of each wire back to the board, then join the other ends of the two wires. Optionally, you can solder another short wire onto the joint, in order to have easier connection to the switch later.
(new wires) |-----------------------...
| : GND
| : 5v
Step 4, use soldering iron to detach the two wires, connected to the original SPDT switch. Now you can say goodbye to the old switch, or save it for other use in the future.
SPDT (Original switch)
| o-+----------- (old wire from PCB, detach)
| o-+----------- (old wire to PCB, detach)
| + |
Step 5, finally, get you new DP switch and solder the wires. Make sure you solder them to the correct pole! For example:
1| o o |4
2| o o |5
3| o o |6
5 and 4, to the wires you just detched from the last step, order does not matter;
2, to the new wires you worked on in step 3;
1, to the new wire you worked on in step 2.
The final wiring should look like the following:
(From power input, 5v)...===============...(to PCB)
(From power input, GND)...===============...(to PCB)
(From power input, 12v)...====>--\
\--+-o o-+-----... (old wire from PCB)
/-+-o o-+-----... (old wire to PCB)
| | o o |
\---<======... (to PCB)
Step Final, put everything back to where they should be.
First, I suggest you to test out everything. Plug in the power and use the multimeter (DC voltmeter) to verify that:
1. when switch is at "OFF", no 5v or 12v output on the HDD power connector;
2. when switch is at "ON", both 5v and 12v are avaliable on the HDD power connector.
Next, it is always a good habbit to tape all your solder points just before you stuck a bunch of wires together.
Finally, repeat what you can perform even in dreams - put back your PSTwo.
Well, if your new DP switch does not fit (usually it is a bit wider than SP switches, but not by much), just grab the file and make the hole fit.
Now I will be attempting the impossible: Repair my HDD's died motor control chip... it is the infamous L6278 1.2, I hope I can get a replacement chip from an old HDD in a computer graveyard nearby... corssing my fingers... >_<
Last edited by Chizuna; 03-09-2007 at 04:26 AM.