I hope this will help

What is the semiconductor on the heatsink, can you see any markings?

 

What is the semiconductor on the heatsink, can you see any markings?

PHIL

 

What is the semiconductor on the heatsink, can you see any markings?

PHIL

 

No other numbers on the other side?

 

No other numbers on the other side?

Just undid the but and bolt from the heatsink no marking on that side

 

This is the circuit diagram i came up with your pcb, the item on the heatsink i think is a Thyristor, i maybe proved wrong.... Can't see any temperature monitoring, just the third terminal feeding the thyristor and charge led, Q1 maybe a PnP?

 

Hi Dave,
I think you have made some errors around the SCR gate area. I think C1 should be in parallel with R2. (- end to gate) I think the diode that you have marked as D2 is the zener and R6 is not in parallel with the zener. (You have also drawn R6 in parallel with the red LED which is where I think it should be. There is also a resistor R3 between the gate and ground which is not visible pn the last group of pictures but it can be seen on the picture in post #3 of the thread.


I have mirrored and rotated the pictureof the etch side to make it easier to match up with the component side.

Les.

 

Hi Dave,
I have not worked out exactly how Q1 works. I suspect it works in conjunction with a thermistor in the battery pack to limit or shut off the charging it the temperature is too high. I think the "SCR" may be a transistor. As the output of the bridge is smoothed to some extent by C2 the current through the control device will not drop to zero at the zero crossing of the AC so if it was an SCR it would never unlatch. If C2 was a reasonably low value then this reasoning would not be valid. (Phill what is the value of C2 ?) There does not seem to be anything to limit the charging current so I wonder if some of the battery packs have short circuit cells. That could explain the blowing fuses.

Les.

 

Yes i think the heatsink is a Npn transistor too, also Q1 makes more sense as a Npn emitter follower.

What does anyone suggest I do with this charger

 

What does anyone suggest I do with this charger

Did you check the fuse again?
What was the result?

 

Did you check the fuse again?
What was the result?

Blown fuse

 

You may have a duff battery as it charged the first one without problem.
Fit a new fuse and see if it will charge that first battery again (if you can identify which it was).
Let us know the result.

 

You may have a duff battery as it charged the first one without problem.
Fit a new fuse and see if it will charge that first battery again (if you can identify which it was).
Let us know the result.

I know which one it is I left the charged one in the drill and I marked the other one.I can not do it no was I amat work till 10:00 pm

 

Here is what i think is the logical circuit,... @LesJones

 

I know which one it is I left the charged one in the drill and I marked the other one.I can not do it no was I amat work till 10:00 pm

If works on one battery ok, i would say you have faulty cells in the other packs, they tend to go short or reversed which takes more current, do you have access to a dvm /voltmeter?
Also what is the marking on Q1, and what is the normal sequence of the leds?

 

Here is what i think is the logical circuit,...@LesJones

As the base of Q1 is connected to one terminal of the transformer secondary then it will be turned on during the positive half-cycle regardless of the state of the battery and so the red LED will always be lit.

Also R7 is a relatively high power resistor and that doesn't make sense unless the charge current flows through this resistor. That would mean that while there was charge current the green LED would be lit. But then what is the point of the transistor on the heatsink?

 

As the base of Q1 is connected to one terminal of the transformer secondary then it will be turned on during the positive half-cycle regardless of the state of the battery and so the red LED will always be lit.

Also R7 is a relatively high power resistor and that doesn't make sense unless the charge current flows through this resistor. That would mean that while there was charge current the green LED would be lit. But then what is the point of the transistor on the heatsink?

I put in a new fuse and charged the original battery and it worked fine,I am going to recycle the other battery.So thank you to all of you very nice people that helped me out.With all that is going on in the world,it is nice to see that there really still is genuinely nice people out there,once again thank you from Hamilton,Ontario Canada.