ZIG CF8 Never giving green LED for Leisure Battery

[g8dhe]

Ahh snap!

[Rhinoman]

or maybe crackle and pop

[g8dhe]

A Crack I think, if it had been heating it for long the board would be discoloured, but the copper seems to be in a couple of globules as well which suggests it acted like a fuse a blew rather rapidly!

[longwori]

Bloody hell !!

I see what you mean. The tracks on either side of C are vaporised! Well spotted guys!

I am the second owner of the vehicle containing the Zig but the person I bought it off said he had never seen the green LED on. Of course I dont know what it has been through but the unit seems to work with the exception of the LED indicators.

I guess if I can get the circuit board out I can repair those tracks. It is held in place by the LED's that are soldered to the other side of the board and fixed to the facia. Im not sure how to get the LED's out of the facia though. They are attached with a black plastic collar. I have tried pushing the LED from the front of the facia hoping they would pop out but with the pressure I have applied so far they are not moving, Its possible they are glued in place but I cant see any obvious signs of glue.

I am not familiar with LED collars do you know how they secure LED's?

[g8dhe]

Several types but all fairly similar;



I think you get the idea, wouldn't be normal to use any sort of glue, but in small production runs where some one drills a wrong hole size I have seen glue used but it would normally be visible from behind the panel.

To release the LED use some pliers behind the panel to work the circular clip back, then the LED should just be free, try not to lose the front of the clip when it falls out from the front of the panel however!

[longwori]

Oh I see. OK, that looks do-able.

Im not sure when I will get the chance now as I will need to de-solder the + and - feed to it too to remove and attempt the repair. It will be easier to calibrate when its off though so well worth doing. Thanks for keeping my enthusiasm to fix it up and I will do it. I just know I will be stuck for time this week and away on business next week.

Thanks for your help and eagle-eyes guys!

I will keep you posted.

Ian

[g8dhe]

When you get it apart, take good close ups of both sides and we can then draw out the circuit.

[tallbongo]

Agree with all the previous comments.

A couple of other things to bear in mind when you get around to it:

1) Is the 8-pin IC soldered directly to the board or in a socket? If the latter, carefully remove it (noting orientation) before attempting any soldering.
2) As the others have stated, you need to find out why the tracks have blown if it wasn't caused by the screwdriver (likely judging by the location of the damaged tracks relative to the pot). It looks to be fairly simple to remove the module entirely if the LEDs are not glued and test it independently of the rest of the system once the circuit is worked out.
3) Close up photos will help identify the circuit routing and many component values, but any you can measure (resistors) or record directly from the components will be very helpful in working out the circuit. Many values on capacitors, pots, etc are difficult enough to see with the component in your hands (perhaps it's just my eyesight going though).

Good luck.

[longwori]

Success!!!!!!!

I nipped home at lunch to do some quick soldering and I now have working traffic lights. I repaired the tracks that had vaporised with wire and have tested it on a spare battery and I can move the potentiometer to switch from green to red. I now just need to decide what voltage to set the switch over at and find a way of producing that voltage so that a can calibrate it before soldering it back into the Zig.

Suggestions for voltages are being accepted now, as are suggestions for creating that voltage from a battery that is currently outputing something like 12.75V. Can I use a separate potentiometer to reduce the voltage to it? I think I have a few in the garage left over from my college days. If I can, I can "dial in" pretty much the voltage I need.

I have photographed the circuit board from both sides as well as I can but I wont bother putting the pics up now its working unless someone feels its worthwhile.

Once again, thanks for everyones help.

Cheers,

Ian

[g8dhe]

Given that you are at the end of along length of cable from the battery itself, you will easily have 0.5 volt drop across the cable as soon as you draw an amp or two so I would set it for 10.5 Volts, this is also the absolute lowest voltage you can get down to on a lead acid battery before the battery starts to suffer, so even if your not drawing any current,and hence no voltage drop, then you are still covered.

As to dropping the voltage to get the setting right, this can be fiddly, as your drawing power for the circuit from the battery under test, unless you can isolate the sensing line itself and feed this separately in which case yes a small pot will do the job something like a 4k7 would be fine. Otherwise try inserting a high wattage bulb in series and then drawing some power whilst measuring the voltage to the unit, but its a bit hit and miss, it might be easier to actually let the battery run down to the required voltage and then set the adjustment at that point.

Yes please put the photo's up or email them to me at least and I'll try to get a circuit drawn out from them, so that we can answer questions more easily in the future the Zig units come up on a regular basis and its always a bit fiddly making guesses as to the problem when there isn't a circuit available.

[longwori]

Ok, it is all installed back in the vehicle and as far as I can tell, working correctly. I have a green LED at least!

I set the voltage using one of those mains universal adapters with selectable voltages and my digital muli-meter stuck in one adapter while the PCB was connected to another.

As promised, here are the circuit board pics. The potentiometer says 100K 611M on the side which may be hard to make out. In the red sleeving on the back of the PCB is a resistor but I cant make out the value due to the sleeving.

The photo with the sun behind it will hopefully help to translate the connections on the back to the components on the front.

Once again, thanks for your help.

[g8dhe]

Excellent news Ian, and I'll draw out the circuit tomorrow after a bit of image processing it looks like this

[Rhinoman]

A typical 741 op-amp circuit, nothing very hi-tech there!

[g8dhe]

Yup you can't get much simpler for the function needed, but then why make it complicated!

That's the board alone, I have some further info on the CF8/9 which I'll combine it with ready for the next problem! If anybody has any extra info on the Zig units, especially circuit info then I'd be happy to receive it and combine it with what I have been collecting over the last year or two.

[longwori]

Great stuff. It may be useful when problem solving in the future. I am away on business now but I have some pics that show (to some extent) more of the internals of the CF8. I dont think it will be clear enough for a circuit to be drawn though as the wires were of limited length, preventing me from moving the facia away from the unit to get a clear picture.

Cheers,

Ian