Need Help: BMC Gear Hub Rebuild Questions?

[geosped]

The bottom of the PCB Board has a bunch of JB' weld on it blocking the holes. In other words I cant put the legs of the hall sensors all the way through on two of the hall's. Yes the tip of my soldering iron is tinned and the legs on the hall's are also tinned. I think when I pried off the epoxy it probably lifted the solder pads on the PCB hence why it's not sticking. :-(

 

[geosped]

I did the hall test and I'm getting the same issues as before. The Yellow and Green wires alternate up to 5v when I turn the wheel but the blue wire stays constant at 5v. Any ideas?

 

[teklektik]

The pull-up resistor to 5V is inside the controller. If you are testing at the hall connector as per normal, then the assumption would be that the hall wire is not being pulled to ground. This could be caused by:

1. bad hall
2. broken hall wire from the connector to the hall
3. broken power or Gnd connection between the hall and the red/black power/Gnd wires inside the motor.

Time for continuity checks.

A quick test (may need a helper):
Since your motor is open, set up your hall test on the connector pins for the offending hall and short the GND and output leads (PCB pads) on the hall to simulate hall operation. You can do this safely with the hall wired in place - just don't short GND to 5V by accident. If the DMM goes to 0V then the hall is bad. If it stays at 5V then you have a bad connection.

 

[geosped]

The pull-up resistor to 5V is inside the controller. If you are testing at the hall connector as per normal, then the assumption would be that the hall wire is not being pulled to ground. This could be caused by:

1. bad hall
2. broken hall wire from the connector to the hall
3. broken power or Gnd connection between the hall and the red/black power/Gnd wires inside the motor.

Time for continuity checks.

A quick test (may need a helper):
Since your motor is open, set up your hall test on the connector pins for the offending hall and short the GND and output leads (PCB pads) on the hall to simulate hall operation. You can do this safely with the hall wired in place - just don't short GND to 5V by accident. If the DMM goes to 0V then the hall is bad. If it stays at 5V then you have a bad connection.

Thanks for trying to help. I'm not really understanding what your saying. Sorry I'm just a noob. What your suggesting is what I think I'm doing. I'm trying to test the hall on the connector pins. Thats how I determined the blue doesnt fluctuate. I have my leads from my meter on black (GND) and the red lead on the blue. The hall is wired in place. But how do I determine which hall leads to the blue wire? I'll have to relook and attempt to trace the blue wire to the hall sensor. I'll do a continuity test on the blue wire from the connector / controller but I need to figure out which hall is related to the blue wire.

I think that the solder pads on top of the PCB board are no longer viable. I cant seem to get a good solder connection. Although there wired in there they seem to move a little. If I have a bad PCB board who carries these?

 

[Alan B]

The PCB is just a replacement for a few wires. You can wire directly if the PCB isn't easy to replace.

 

[geosped]

The PCB is just a replacement for a few wires. You can wire directly if the PCB isn't easy to replace.

You guys make it sound so simple lol. Care to elaborate? I'm no electronics wiz. I do have the basic tools though.

 

[teklektik]

Yep - so many different skill levels...

The general idea is to map out the PCB traces to identify how they connect the colored hall wires to the offending hall (red,black,{grn|blu|yel}). A little drawing of the pad locations and how they are connected can save a misstep, but do what works for you. Then using some very small gauge wire, jump the pads from the hall wires directly to the the hall leads. Here you would just be using the PCB as a mechanical mount for the hall and essentially bypassing the (probably?) faulty or severed traces. Since what you are doing will essentially parallel the existing traces, you can leave your existing soldering in place to help position the hall and just tack the new leads on from there. A bit of epoxy when you are done will hold the stuff in place and insulate things if you used bare wires. Just be aware of altitude since the whole thing has to fit back in the case without rubbing on adjacent members.

I'm guessing you don't have a supply of various wire gauges on hand, so you can get the tiny wires by salvaging an old electronic cable or by taking uninsulated strands from a heavy bit of multi-stranded mains wiring. A scrap VCR, etc can easily render up the needed materials.

Frankly, this is fussy work with tiny bits and a lot of 'wing it', so your technician skills may be pressed. On the other hand, this is how we all got the skills in the first place, so welcome to the club...

 

[Alan B]

Ethernet cables with stranded wires are good sources for some nice small gauge wire. An assortment of heatshrink from Amazon or Ebae would be useful also. Liquid tape can be used to protect connections as well.