B&M Cyo Troubleshooting & Repair

[sfCyclotourist]

BIG photo of the business side of the PCB:


B&M Cyo PCB by jimgskoop, on Flickr

 

[Steve K]

hi Jim,

A close up of the deceased component and the immediate surrounding area should be adequate. I'm not sure what any of us will really be able to figure out about it, but what the heck!

It might be useful to have a shot of the nearby IC too. That might provide hints about the funtion of the deceased component.

regards,
Steve K.
(the other other Steve)

 

[sfCyclotourist]

Here ya go Steve...


B&M Cyo PCB by jimgskoop, on Flickr

 

[Bandgap]

Had a good look at the photos of my unit.

Sadly, mine is a different PCB.

With no small components on the super-cap side.

Steve

 

[Steve K]

Here ya go Steve...

shoot... I'm still scratching my head trying to figure out what that part is.

It looks like it is smaller than the sot-23 device located on the other side of the SOIC-8 part.
Almost looks like the top of the package is blown off?? You would need to remove the
super-cap and move the two wires out of the way to get a good look at the part.
Even then, my guess is that there is no surviving marking to hint at what it might have been.

I was hoping that the dead part might be associated with the adjacent SOIC-8 IC package
part, but I don't see a connection or trace that links them. Somewhat off topic, is that SOIC-8
a 555 timer?? Makes me wonder what its function is. The resistor labeled "685" also has me
curious.... a 6.8M ohm resistor?? or am I reading it wrong? What would you do with a resistor
of that value?

I guess I'd remove the dead part from the board (carefully) and see if the board works. That
might let you get a better look at the dead part too. Other than eating up some time, you don't
have a lot to lose.

Steve K.

 

[2_i]

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 ran mine in tests with DC of both polarities and have in fact pumped up the voltage quite substantially without ill effects.
Otherwise in everyday life I run my Cyo with one sign only of the 'wrong' polarity.

 

[Martin_]

@sfCyclotourist:
I noticed it's an old post but I have the same issue, exactly the same component is gone up in smoke (at least
it looks like that). Did you succeed in repairing (by removing or replacing the component)?

Thanks in advance,
Martin.

 

[sfCyclotourist]

@sfCyclotourist:
I noticed it's an old post but I have the same issue, exactly the same component is gone up in smoke (at least
it looks like that). Did you succeed in repairing (by removing or replacing the component)?

Thanks in advance,
Martin.

I ended up gutting the light, replacing the dead PCB with a simple bridge rectifier and capacitor circuit, plus switch. I did harvest the supercap and the LED from the original circuit. It now might not be quite as bright as a stock Cyo, but it's been working great for over a year.