B&M Cyo Troubleshooting & Repair

[sfCyclotourist]

A friend gave me a dead B&M Cyo headlight to play with. I've opened up the unit and verified that the LED is still good. Near where the tail light wires are soldered onto the PCB is a tiny burnt component -- I'm guessing that the tail light wires (which weren't connected to anything, nor were they covered over) touched and shorted something out.

I have very little idea where/how to start debugging this thing, to hopefully repair it. Any tips or suggestions?

If I can't fix it, I'm going to remove the fancy PCB and just replace it with a simple rectifier circuit -- that way I'll at least have a useable light with the good reflector & housing.

Thanks!
-Jim G

 

[panicmechanic]

Just by chance: can you identify the burnt part in one of these pictures? Well, you might know them anyway...

 

[sfCyclotourist]

The PCB on the light I have actually looks slightly different than the one in those German photos. I'll have to snap some pics of it tonight. The fried component is on the very edge of the PCB, right next to where the tail light wires are soldered, but on the other side -- underneath the big blue 5.5V 1F cap. I think I need to remove that cap to see it properly, in fact...

 

[syc]

The PCB on the light I have actually looks slightly different than the one in those German photos. I'll have to snap some pics of it tonight. The fried component is on the very edge of the PCB, right next to where the tail light wires are soldered, but on the other side -- underneath the big blue 5.5V 1F cap. I think I need to remove that cap to see it properly, in fact...

I have a working Cyo that is sitting around. Are you free this coming week for me to pay for and pickup the Vent Noir? I can bring the Cyo around and we can see if we can identify the part, or at least, find the non-fried version and have someone like Matt try to id it.

Steve

 

[syc]

I finally got around to opening up the Cyo this afternoon. Does this image help any?

 

[Steve K]

it's hard to be certain, but the SOT-23 by the lower left corner of the inductor looks sort of funny. Is this real damage, or just image compression?

what's on the back side of the board?

thanks,
Steve K.

 

[panicmechanic]

Steve, I'm afraid that's an intact part shown by syc for comparison only. No need yet to check for defective parts

 

[Illum]

heres a better view of what sfCyclotourist was referring to [reehosted pics]:

though I'm not sure if thats a burned out component or just rosin that flowed about during assembly, noting the cap pins in the center

 

[Steve K]

heres a better view of what sfCyclotourist was referring to [reehosted pics]:


though I'm not sure if thats a burned out component or just rosin that flowed about during assembly, noting the cap pins in the center

Looks like flux to me. Those are the through-holes for the LED wires, aren't they?

just wondering.... can you tell what the switching power supply IC is?

regards,
Steve K.

 

[Illum]

Looks like flux to me. Those are the through-holes for the LED wires, aren't they?

just wondering.... can you tell what the switching power supply IC is?

regards,
Steve K.

No idea, the SOIC-8 Appears to be from Fairchild semiconductor

PH858
4420

the big SOIC-14 is equally perplexing, no info what so ever

CMO1068
88K G4
F44M

 

[sfCyclotourist]

Here's a photo of the guts of my Cyo. Sorry for the blur...

The fried component is right at the edge of the PCB, under the black wire in the center of the photo. You can see it better highlighted at http://www.flickr.com/photos/jimg/4869751676/

 

[panicmechanic]

Well, my board differs a bit (it's from a Rebel-equipped 'Sport' Cyo with switch and light sensor), but my photo came out better :naughty:

Is it the '472' resistor? Next should be a diode, all covered in a clear coat that prevents me from reading (apart from font size :duh2.

 

[sfCyclotourist]

Well, my board differs a bit (it's from a Rebel-equipped 'Sport' Cyo with switch and light sensor)

I thought all versions of the Cyo use the same LED?

Is it the '472' resistor? Next should be a diode, all covered in a clear coat that prevents me from reading (apart from font size :duh2.

I think that's it, yes -- right on the edge of the board. So it's just a resistor? Why would that kill the entire board? I'm thinking of trying to unsolder/remove it, and see if the light might work without it (assuming that it's shorting everything out). I don't need the tail light connection...

Thanks!

 

[panicmechanic]

I thought all versions of the Cyo use the same LED?

Let's say most of them come with XR-Es, some, probably earlier ones, had Rebels.

So it's just a resistor? Why would that kill the entire board? I'm thinking of trying to unsolder/remove it, and see if the light might work without it (assuming that it's shorting everything out). I don't need the tail light connection...

Thanks!

You're welcome. Definitely a resistor in my board.
I can imagine someone put power to the taillight connectors and caused some more damage. I'm not an electronics guy, but to my limited knowlegde the diode could be there to block that :thinking:

 

[sfCyclotourist]

Borrowed my wife's camera tonight, here are some better photos...

The full-size originals can be found at http://www.flickr.com/photos/jimg/

My light seems different than others I've seen, in that the tail light & main wires exit the PCB on the same side as the supercap....?

 

[panicmechanic]

Yes, layouts seem to vary. That's why you need the electronics gurus, and you should take pics with the supercap removed.
My pcb seems more similar to yours than the one I linked to in the second post, still there are differences. You'll have to find someone who understands the layout. I could only supply comparison shots, if needed.

Edit: the burned part in your board is not a resistor, it must be one of these three-legged insects.

 

[Steve K]

Shoot! I went to the Flickr page, thinking there would a focused picture. nope...

If there are any markings on the device, that might help a little in identifying it. If, for instance, it was a transistor, the markings may clarify the type if we can make a good guess at the manufacturer, general catagory of part, etc. The parts nowadays are so small that it is almost impossible to figure out what the part is.

If you had access to a good Cyo, a few measurements with a meter might at least tell you if it is a npn transistor, mosfet, etc.

If all other options look pretty lousy, you might just try removing the deceased part and see if that lets the light work. The part might just have been there as part of the power conditioning circuitry for driving a taillight??

regards,
Steve K.

edit: I was looking at the original fuzzy pic. The later pics are much better, but I would still like to see more detail. I'm assuming that you are using the macro mode. I've had some luck with using a magnifying lense in addition to the macro mode. A tripod can come in handy, though.

I'm surprised to see what looks like a burn mark on the board. And is the trace gone on one of the leads? I think this is a perfect time to find out who your true friends are.... i.e. someone who will let you take apart their Cyo and make some measurements on the board. :laughing:

Steve K.

 

[Bandgap]

I wonder if someone had put a battery across the terminals.

The directions say it can be done, but you have to be strict with the polarity, and there is also a voltage limit which also seems to be strict.

I have had mine apart.

I only have photos of the non-supercap side on this computer.

Will try to remember to look at home.

The other Steve

 

[Notsure Fire]

This is getting interesting. I'll keep coming back to see the progress.

 

[sfCyclotourist]

If all other options look pretty lousy, you might just try removing the deceased part and see if that lets the light work. The part might just have been there as part of the power conditioning circuitry for driving a taillight??

That's what I'm thinking of trying.

edit: I was looking at the original fuzzy pic. The later pics are much better, but I would still like to see more detail. I'm assuming that you are using the macro mode. I've had some luck with using a magnifying lense in addition to the macro mode. A tripod can come in handy, though.

Steve, I can post larger/higher-res photos, I just didn't want to clog up the board. Tell me which photos you're interested in...

I'm surprised to see what looks like a burn mark on the board. And is the trace gone on one of the leads?

There definitely is a burn mark on the edge of the PCB -- you can see it in the first of the last set of photos I posted. That's the edge of the board where the cooked resistor(?) is mounted near the tail light connections, which I assume touched together and shorted it out while the previous owner was riding. Which trace looks like it's gone -- I hadn't noticed that?

Thanks,
-Jim G