Ice Tube clock stopped working

by dub on Sun Jul 15, 2012 3:53 pm

My daughter and I built Ice Tube clock for her.

It worked fine, and is one of our favorite projects. Thanks for the kit!

Here is a little note from my daughter:
The alarm clock got me out of bed great! Thanx!

A while later it stopped working - after a drop :(
The clock beeps when plugged in, but nothing lights up on the tube.

We just measured the voltages that troubleshooting guide mentions:

Pin 1 of IC3 : 9.00
Pin 3 of IC3 : 4.99
Bias voltage: 4.72
Boost with no tube or VFD chip: 57
With VFD chip installed it is 47 volts instead of 14-16!

I am not sure what to check/do next; any help is appreciated :)

Thanks!
dub
 
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Re: Ice Tube clock stopped working

by adafruit_support_bill on Sun Jul 15, 2012 6:00 pm

The most fragile component in the kit is the tube. It can easily be damaged by the shock of a drop. I wouldn't expect the VFD chip to be damaged by the shock of a drop itself. But I suppose it is possible that something shorted in the tube that took out the VFD chip too.

We do have spare tubes in the store. We do not carry the Max6921 VFD chips, but you should be able to order them direct from Maxim.
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Re: Ice Tube clock stopped working

by dub on Sun Jul 15, 2012 8:31 pm

adafruit_support wrote:The most fragile component in the kit is the tube. It can easily be damaged by the shock of a drop. I wouldn't expect the VFD chip to be damaged by the shock of a drop itself. But I suppose it is possible that something shorted in the tube that took out the VFD chip too.


I suspected something like that :)

adafruit_support wrote:We do have spare tubes in the store. We do not carry the Max6921 VFD chips, but you should be able to order them direct from Maxim.


I found MAX6921AQI at Mouser. Is that the part?

Thanks!
dub
 
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Re: Ice Tube clock stopped working

by adafruit_support_bill on Mon Jul 16, 2012 5:00 am

I found MAX6921AQI at Mouser. Is that the part?

That is the one :)
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Re: Ice Tube clock stopped working

by dub on Fri Aug 10, 2012 9:48 am

I got the replacement VFD chip, but with it boost voltage is still 47 volts.

What do I do now?

Thanks!
dub
 
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Re: Ice Tube clock stopped working

by adafruit_support_bill on Fri Aug 10, 2012 11:29 am

And the tube still does not light?

It is possible that one or more traces or component leads on the board were cracked in the drop. It may not be apparent just looking at the board, but might become visible if you gently flex it. Since the processor seems to be running fine, focus on the end of the board from the boost circuit on.
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Re: Ice Tube clock stopped working

by dub on Fri Aug 10, 2012 11:58 am

adafruit_support wrote:And the tube still does not light?


The old tube is cracked; the new one I did not yet solder into the side-PCB.
Even if I had, is it safe to plug it in with the voltage so mach higher than normal?
(And there is a chance that it'll light somehow?!)

adafruit_support wrote:It is possible that one or more traces or component leads on the board were cracked in the drop. It may not be apparent just looking at the board, but might become visible if you gently flex it. Since the processor seems to be running fine, focus on the end of the board from the boost circuit on.


OK, I'll try that! Thanks!
dub
 
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Re: Ice Tube clock stopped working

by adafruit_support_bill on Fri Aug 10, 2012 2:06 pm

The voltage is high, but the current is pretty low. It doesn't take much load to drag it down. That is why it typically drops when you install the VFD chip. The drop is quite variable, but 47v does not sound normal. Look it over carefully for breaks.
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Re: Ice Tube clock stopped working

by stinkbutt on Fri Aug 10, 2012 10:07 pm

I'm not sure if a high voltage while the tube is unconnected means anything. Boost converters with no loads operate at a higher voltage than they output when loaded.
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