Hi MrChips,
I jumped in with post #19 with that thought I had overnight without reading recent posts. I now realise that you have isolated the problem to being very close to the + 12v input. I suspect that jumper JP3 may link the incomming +12v. I have seen the metal insert in these jumperts falling out. It might be worth testing the pins both sides of the jumper fo 12 volts.

Les.

 

Hi MrChips,
I jumped in with post #19 with that thought I had overnight without reading recent posts. I now realise that you have isolated the problem to being very close to the + 12v input. I suspect that jumper JP3 may link the incomming +12v. I have seen the metal insert in these jumperts falling out. It might be worth testing the pins both sides of the jumper fo 12 volts.

Les.

Yes. Remove J3 and inspect.

 

IIRC I believe the blue LED light would come on and drive spin up whether or not cables were connected.
But ... I will keep that in mind and go look up the manual and see if it says anything to that effect.

Resuming Trace after a noon mtg with friends.

 

Continuity
Comments on J1?

 

Check the voltage on both ends of FB5 (Which I suspect could be a fuse.) I can't folllow tha tracks for the +12 volts to it but it could be on the 12 volt line.

Les.

 

Continuity for various paths
Also showing Red, Black and Yellow wire posts
HDD hard disk drive receptacle
Also wondering (ISO) about continuity between Red wire SW posts 1 or 2 > Q4 > U8 > HDD3
(apologies for any symbol misuse or color confusions)

 

I am assuming that by SW3 you mean the third pin (Counting from the right.) on the 4 pin connector. It looks like fuse FB5 is directly before the 12 volt contacts on the switch so the fault must be between the bottom end of FB5 and the input. It looks like there is a track on the underside of the board that goes from the plated through hole below FB5 in the direction of D2, Check to see if there is continuity between the bottom of FB5 and any of the connections on D2 or R55 or R56. Below what value of resistance reading are you defining continuity ?

Les.

 

Continuity is when Resistance measures less than approximately 30 ohms (according to the manual)
Yes, number right to left on top, left to right on bottom 1-4.
Trying to trace what you ask on the bottom not obvious at first.

 

I am assuming that by SW3 you mean the third pin (Counting from the right.) on the 4 pin connector. It looks like fuse FB5 is directly before the 12 volt contacts on the switch so the fault must be between the bottom end of FB5 and the input. It looks like there is a track on the underside of the board that goes from the plated through hole below FB5 in the direction of D2, Check to see if there is continuity between the bottom of FB5 and any of the connections on D2 or R55 or R56. Below what value of resistance reading are you defining continuity ?

Les.

Below 30 ohms Resistance is defined as Continuity by the Extech MiniTec 24

I don't see any access to below FB5 ... near C18

I measured continuity on top as in the attached diagram: from FB5 to others, and from the Receptacle Side Plate to others.

This may be out of my capabilities? although willing to learn.

 

There is a hole near the bottom end of the track from the bottom of FB5. (This is called a plated through hole. It makes a connection between tracks on the top of the board and the bottom of the board.) You need to locate this hole on the bottom side of the board and follow where that track goes to. (I normaly poke a thin strand of wire through the hole to be sure I am looking at the same hole from the other side.) Some boards have more than two layers of tracks. The extra layers are within the board. This makes it even more difficult to trace out connections.

Les.

 

Disconnect the 12VDC power jack.

Examine the board visually and with the aid of a continuity tester (the diode test on your DMM).

Try and trace how the 12VDC gets to the 4-pin connector.
Pin-3 ought to have a direct connection to the 12VDC input jack. There should be a trace on the component side (top side) of the board.

Hi Mr Chips ... should have asked before ... Which Pin are you calling Pin-3? I looked at the bottom of the board, and counted left to right. This makes Pin-3 2nd from right on bottom, 2nd from left on top.

Is that the one that should be connected to the 12V of the Receptacle? It would also be associated with a Yellow wire of the SWitch.

 

I am working on the assumption that 12VDC flows through from J1 to SW, to the switch back to SW (yellow cables), to U8 pin-1, to the HD power connector, pin-1 (yellow cable).

The square PCB solder pad on each connector is pin-1.

What is the part number of Q4?

What role does FB5, JP3, JP2 play in the circuit?
You need to reverse engineer the PCB, i.e. follow the PCB traces to figure out what they do.

Stick with this and I am certain that you will be able to solve this.

 

As part of the Reverse Engineering: there are no Jumpers on JP1 or JP2.

Perhaps other noobs will find these links useful (I'm reading these now):
https://learn.sparkfun.com/tutorials/pcb-basics/all
which leads me to this and others:
https://learn.sparkfun.com/tutorials/how-to-read-a-schematic

I'm also getting a Magnifying Visor soon. Decided to try this one:
https://www.amazon.com/gp/product/B007CDJKM2/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

Onward ...

 

Sorry, the newly posted photos do not help us.
Only you can figure this out because you have the board in hand and can see more clearly where the tracks go.

Begin with the 12VDC jack J1.
The center pin goes to JP3.
From JP3 it has to connect to SW-3.
How does it get there?

Now let us work backwards from the HD power connector.
Pin-1 of this connect has to connect to U8-1.
It also has to connect to SW-4.
Can you confirm this?

SW-3 means SW pin-3
SW-4 means SW pin-4
U8-1 means U8 pin-1

 

I am working on the assumption that 12VDC flows through from J1 to SW, to the switch back to SW (yellow cables), to U8 pin-1, to the HD power connector, pin-1 (yellow cable).

Note found for power to hard drives: usually "3 wire, and they can not just be connected to power, the control IC is a 100 Pin QFP..." is that U8? or is that IC 100 Pin QFP on the HDs circuitboard?

U8 - Integrated Circuit > Voltage Regulator (?)
S_K
3D3 (D16) 208
8 0 5 0 J D


U8-1 numbering 1,2,3,4,5 Top to Bottom (HD Power connector at Top)
testing continuity:
No continuity U8-1 and HD1 (Yellow)
Continuity
HD1 (Yellow) and SW2 (Red)
HD3 (Red) and SW4 (Yellow) "quick blip", but not continuous sound
FB5 and SW3 (Yellow so also SW4 if SW closed so U8-1)
U8-1 and SW4 (Yellow)
U8-2 and HD3 (Red)
U8-3 and HD2 (Black)
U8-4 and HD3 (Red)
U8-5 none so far

The square PCB solder pad on each connector is pin-1.

This convention is being followed.
Connector Pins from Top:
HD Power 3 2 1
SW 4 3 2 1
LED 1 2 3

What is the part number of Q4?

Q4 a Thermistor?

4D Company Symbol (unclear)
440S
B0351C
Now exploring these:
https://octopart.com/
https://www.digikey.com/en/articles...-to-use-digi-key-part-search-more-efficiently

What role does FB5, JP3, JP2 play in the circuit?

FB5 Fuse to protect board from power in?
JP2 No Jumper across
JP3 Jumper?

You need to reverse engineer the PCB, i.e. follow the PCB traces to figure out what they do.
Stick with this and I am certain that you will be able to solve this.

Working ...

 

Sorry, we are going around in circles.
We have already identified that U8 is a Sanken SI-8050JD 12VDC to 5VDC buck converter.

I am going to ask you to repeat your continuity tests. There are some inconsistencies in previous tests.
Remove JP3.

Connect BLACK lead to HD-1.
Measure continuity at the following points
U8-1
U8-2
U8-3
U8-4
U8-5
SW-1
SW-2
SW-3
SW-4
JP2-1
JP2-2
JP3-1
JP3-2
Q4-1
Q4-5



Repeat all the above tests with BLACK lead connected to HD-3.

 

Note: 1 is usual resting Display Value
(000 is resting value with a beep)
Below: X=No Beep Y=Beep

Black HD-1HD-3
U8-1 X X
U8-2 X Y (beep resting on 000)
U8-3 X 132 (steady, no beep)
U8-4 X Y (beep resting on 000)
U8-5 X X

SW-1 X 1200 (flash then back to 1, no beep)
SW-2 Y 1900 (flash then back to 1, no beep) (HD-1 beep resting on 000)
SW-3 X X
SW-4 X X

JP2-1 X 137 (quick beep then steady value)
JP2-2 X 1802 (steady, no beep)

JP3-1 X 1626 ((steady, no beep)
JP3-2 X X

Q4-1 X 1645 (steady, no beep)
Q4-5 X 793 (flash back to 1)

I believe this is accurate (repeated several times)

Questions:
For Display steady values with no beep, would that indicate a flow but only slightly greater 30 ohms?
For values that flash then disappear, is that connected to a capacitor that might retain a minute charge from the Meter?

 

Is there any possibly that the HD connector and the SW connect can be plugged in backwards?
I would expect that the connectors are keyed to prevent improper connection.

 

Something still does not add up.
At this point, I am not interested in any capacitor charging. I am looking to see what is a direct connection to what.

Can you do a similar test, this time we use the pins on SW as our starting point?
For example, start with SW-1 and look for open (1---) or closed (000 with beep) to all of the other test points listed above.

Do the same for SW 2, 3, and 4.

 

After you have done the above tests. do the same using J3-1 and J3-2 as your reference point.