Paul & Sabrina's cheap DIY 144v motor controller

[MPaulHolmes]

Originally Posted by amino

I have been trying to trace the fault. With the controller on the bench again, I checked the voltage at pin 2 of the optoisolator U9, and it reads 4.91V on switching on and 3.75V after precharge. There is no change at pin 4 though.

OK, can you see what the voltage is on each side of R23 relative to ground before and after precharge?

[MPaulHolmes]

Actually I think that's fine. 3.75v down from 4.91v sounds OK, since it's just going to be a voltage drop from the diode. It sounds like the optocoupler isn't working for some reason.

[amino]

I am getting 4.91vbefore and 0.22v on the U3 side
and on the U9 side of R23, 4.91v before and 3.75v after precharge .
At pin 4 and now it shows 11.09v before and 7.63v after precharge.

Will I need to get the exact replacement optocoupler, or can I use a substitute?

Amin

[MPaulHolmes]

I can send you another one, but it might be quicker for you to stick in another one. Here are some of the specs for it:

HCPL-817-000E Avago Technologies Transistor Output Optocouplers

So I guess something that's similar to that.

These are very good:
FOD817D300W Fairchild Semiconductor Transistor Output Optocouplers

Do you want me to mail you one of each, straight from Mouser?

If you short from Pin 4 to Pin 3 on U9 (maybe with an alligator clip or something), does the contactor close? Be careful not to do this before the precharge has happened. I would verify that the capacitors are full first. If the contactor closes, then Q1 is good.

[amino]

Yes, the contactor does close when I short Pin 4 to Pin 3 on U9 (with a pencil lead point). I have the controller on the bench with just the 12 volt supply going to it. It is on a board with the contactor and fuse as an assembly, making it easy to connect and remove from the car.

I will let you know if i cannot find a suitable optocoupler here.

Amin

[MPaulHolmes]

I"m just curious why it's not working. Collector to emitter voltage maximum is 35 volts, but I think those fail shorted. It might still work, but maybe it just has a horribly crappy current transfer ratio?

[amino]

Paul, My knowledge is somewhat limited when it comes to optocouplers and semiconductors in general. Maybe the heat from soldering iron affected it?

Amin

[MPaulHolmes]

Nah... Rule #1. Blame someone else when it doesn't work.

New controller soldering a success!!!:



Oh no! They are going to fall on the ground! hahaha.


Each of these would take about 30 bashes with a hammer and flathead screwdriver to remove:


That was just the diode bar. Tomorrow is the MOSFET bar! The process is easy now that I have it down.

[flores]

Paul, are those glued on?

[flores]

Soldered right.. but I don't see any solder?