Reviewing Wire Colors and Plug Positioning

 

Red and yellow wires at SW do not conform to HD colors.

SW-3 and SW-4 (yellow) supplies power to U8-1 voltage converter. We don't as yet know where it gets power.

 

I'm studying this layering of the front and back of the board, trying to determine, among other things, paths of the 12VDC power.
The back view is reversed, aligned with the front, set at 50% transparency, and placed on top of the front view.
If this doesn't help, I'll remove it from the thread.
(I replaced image with improved version)

 

What is Q3? Is something missing? black box like Q4?

 

I think from the readings from post #60 you have gone as far as you can. If we are correct that Q4 is a P channel mosfet then it is not being switched on. It would need pin 4 pulled low to turn it on. It is just possible that Q4 is a PNP transistor but I have never seen one in that type of package. If it was then 1.6 volts between its emitter and base is more than I would expect as that junction should behave like a forward biased diode. I think tracing the source of this signal would just take us via an NPN transistor (Or N channel mosfet.) to a pin on one of the large ICs. We dont know what conditions are required to enable Q4. We now know it is not just the presence of the 5 volts from the USB. It could be a problem with the driver software as it is not seen by the computer. Think about things like Has it ever worked on this computer. Has the softwre been updated. Did you have to load drivers from a disk supplied with the device or downloaded from the web.

Les.

 

Q3 is unpopulated, similar to Q4.
Q3 is in parallel with JP3 and hence JP3 serves the same function, i.e. extra power trace bridge.

As yet, we do not have the exact part number of Q4
FDS4675 is an example of a P-channel PowerTrench® MOSFET.
In any case, this switches 12VDC input, in series with JP3, SW-1-2 (red), to HD1 (yellow).

We are not sure of the function of JP2.
Is JP2-2 connected to Q4-4?

We still do not know how SW-3-4 (yellow), and U8-1 gets its power input (via FB5).
U8-2 and U8-4 supplies +5VDC to HD-3 (red).

 

Isolating the Part Number of Q4: http://www.aosmd.com/products/mosfets/p-channel/AO4405
(lighting)


Here is the Alpha & Omega Semiconductor AO4405:
http://www.aosmd.com/res/data_sheets/AO4405.pdf
BD351C is the package manufacturing marking:
http://www.aosmd.com/res/markings/AO4405.pdf

 

Description of U8
https://www.semicon.sanken-ele.co.jp/ctrl/en/product/detail/SI-8050JD/

 

We are not sure of the function of JP2.
Is JP2-2 connected to Q4-4?

There is no Jumper on JP2
JP2-2 is not connected to Q4-4.
I noted that Q4-4 measures 10.4VDC when USB2 is connected to a computer.
Note: After Posting, I just measured without USB2 connected, and with Power In connected, and Q4-4 measures 10.6VDC.
JP2-1 is connected to Grounds. (HD-2, 4 corner connecting points, right side of D9 or D9-1)

Yes, this external drive worked with my current computer (Mac Pro 3,1 under OSX 10.6.8).
Nothing has changed to alter this.
There was no hard drive connected when we tested so that may be why the board didn't show up in the Apple Profiler.

Continuing to study for 12VDC power to SW-3,4 and U8-1

 

I reassembled the enclosure to test for recognition.

With USB2 and Power In connected, Apple System Profiler does not see it. No LED with SW On.
With FW400 connected, and Power In, I get a Blue LED with SW On, and Apple System Profiler says Unrecognized Device on FW channel.
HD does not spin up in either case.

According to descriptions of the harddrives, it needs a signal from the 5VDC to spin up, 12VDC to spin.

 

I bought a similar OWC model for comparison
(adds FW800 to FW400 and USB2) for $15 + $10 Shipping.

Having 2 spare Seagate IDE/PATA drives, 500GB and 750GB to house, a 2nd enclosure will be useful.

 

Voltage Measurements
FW400 / USB2 + 12VDCPowerIn + SW ON
(FW or USB)

FW400 / USB2
LED ON / OFF

HD-1 3.1 / 2.7 (Should be 12V ?)
HD-2 0.0 / 0.0 (Ground)
HD-3 4.9 / 0.0 (Good at 5V ?)

U8-1 11.2 / 2.6
U8-2 5.1 / 0.0
U8-3 0 / 0.0
U8-4 4.9 / 0.0
U8-5 2.4 / 0.8

Q4-1 12.0 / 12.0
Q4-2 12.0 / 12.0
Q4-3 12.0 / 12.0
Q4-4 12.0 / 11.7
Q4-5 3.1 / 2.8
Q4-6 3.1 / 2.8
Q4-7 3.1 / 2.8
Q4-8 3.1 / 2.8

 

Could that mean HD1 is getting power, but not full 12VDC?
Is something connected to it not working to full capacity? Like C54?
C54 seems to go to HD-3
C53 to SW1? or SW1,2,3?

 

Power Routing (in progress ...)
With intermingled communication from FW or USB ports ... looking for correct voltage flow between 1, 2, and/or 3 Capacitors, an Inductor, Sanken Buck Converter, Switches and final destination HD3,2,1 of 5V, Ground, 12V hard drive power )
Back at 50% Layered Over Front

U8 Usage: "The regulator can be composed of input / output capacitor, diode and coil."
see http://www.semicon.sanken-ele.co.jp/sk_content/si-80xxjdseries_an_en.pdf

SI-8050JD
C1 220 µF 35V C55 (STONE Aluminum Electrolytic)
Lead Spacing 3.0mm Diam 8.25mm H 14mm
Match?: https://www.digikey.com/product-detail/en/rubycon/35ZLH220MEFC8X11.5/1189-1863-ND/3563385
http://www.rubycon.co.jp/en/catalog/e_pdfs/aluminum/e_zlh.pdf
C2 330 µF 35V C53(STONE Aluminum Electrolytic)
Lead Spacing 3.75mm Diam 8.25mm H 16mm
Match?: https://www.digikey.com/product-detail/en/rubycon/35ZLH330MEFC10X12.5/1189-1891-ND/3563615
https://industrial.panasonic.com/cdbs/www-data/pdf/RDF0000/ABA0000C1255.pdf
C3 __ µF __V C54 (SMD Ceramic)
L1 __H Inductor 20395
Di Diode D9 SK34 D8 SK110
=Q4 MOSFET============================================================

Q4: http://www.aosmd.com/res/data_sheets/AO4405.pdf


C60-1 (12V PowerIn Top Solder Strip) > JP3-2,1 > Q4-1,2,3
??? (Firewire U10 > D3 > D2) or (USB U7 > Q5 > Q2) > FB5 > Q4-4
Q4-5,6,7,8 > L1-1 > U8 > D9 SK34 > +C53 > D8 SK110 > +C55
======================================================================
Back and Right Side of Front

5V Conditioning Path:
U8-1 > D9 & +C53 > L1-1 (Vin)
U8-2 > D8 & +C55 (SWout)
U8-3 > Ground
U8-4 > L1-1 Vos > C55
U8-5 > D8 ON OFF > C54
L1-1,2 > SW1 & —C55 > —C53 > HD3
SW3,4 > +C55 > HD3
12V Conditioning Path:
L1-1 > D9-2 > +C53 > SW1 > SW2
SW2 > HD1
HD1 > SW3