Tube not lighting

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tcymrot
 
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Tube not lighting

Post by tcymrot »

I'm hoping someone can help us troubleshoot. My daughters have been working on building the ice clock and every test was successful, but when it came time to get the tube to light up... no dice.

With the tube in place, here are the voltages we found:
-At R3 10.4v
-At D3 10.4 v
-At the ISP closest tab 8.7v
-At the ISP furthest tab 4.8v

With the tub removed, the voltages are:
-At R3 13.9V
-At D3 13.9V
ISP maintains the same voltages

We looked up this problem on the forums and tried jumping Q3, but no change.

We'd appreciate any advice! Here are some photos (I know the soldering job is a bit messy... I tried going over any possible weak joints and may have ended up with too much solder on a bunch of them).
iceclock1.jpg
iceclock1.jpg (576.43 KiB) Viewed 841 times
Iceclock2.jpg
Iceclock2.jpg (252.68 KiB) Viewed 841 times
Iceclock3.jpg
Iceclock3.jpg (228.59 KiB) Viewed 841 times

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tcymrot
 
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Re: Tube not lighting

Post by tcymrot »

Here are three more pictures:
iceclock4.jpg
iceclock4.jpg (244.48 KiB) Viewed 840 times
Iceclock5.jpg
Iceclock5.jpg (192.28 KiB) Viewed 840 times
iceclock6.jpg
iceclock6.jpg (158.88 KiB) Viewed 840 times

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tcymrot
 
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Re: Tube not lighting

Post by tcymrot »

Sorry, one more clarification... where I wrote ISP, I meant "IC3"... the regulator chip!

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adafruit_support_bill
 
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Re: Tube not lighting

Post by adafruit_support_bill »

Do you get the beep on power-up?

On a few of your solder joints, the solder is balled-up around the pin. That sometimes means that the solder has not flowed well onto the solder pad. This guide has some tips on identifying and fixing these:

https://learn.adafruit.com/adafruit-gui ... n-problems

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tcymrot
 
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Re: Tube not lighting

Post by tcymrot »

I'm afraid that any excess solder is a result of my going over the girls soldering... I can try retouching these again, but I don't think it is the source of the problem. We do get the beep on power up, and all other tests have the expected voltage. We jumped the Q3, and no change.

When we put the ground probe at the IC3 and touch the red probe to the wire leads on the vacuum tube we get fluctuating voltages, and uneven voltages depending on which side of the tube. Does this indicate anything in particular? Are there other tests we should be doing isolate the specific site of the problem?

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adafruit_support_bill
 
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Re: Tube not lighting

Post by adafruit_support_bill »

So the processor is running, but the boost converter isn't boosting. Can you post a top-down shot of the component side so we can see all the components? Double check the orientation of Q2. The bridged pins should be adjacent to D3.

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tcymrot
 
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Re: Tube not lighting

Post by tcymrot »

Thanks for your help with this... we double checked and Q2 appears to be oriented correctly. I'm attaching a few more top down photos. Any further meter tests we can run to isolate the source of the problem?
clock_d3.jpg
clock_d3.jpg (60.47 KiB) Viewed 772 times
clock_top.jpg
clock_top.jpg (63.35 KiB) Viewed 772 times
clock_topIII.jpg
clock_topIII.jpg (66.11 KiB) Viewed 772 times

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adafruit_support_bill
 
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Re: Tube not lighting

Post by adafruit_support_bill »

That all looks correct. The boost converter is driven by Q2 which is controlled from pin 12 of the main processor. If you have any access to an oscilloscope, it would be helpful to see if there is signal on pin 12. A meter reading would be less conclusive, but I'd expect to see something less than 5v on that pin.

Looking at the solder-side photos, the solder joints where Q2 connects to D3 look a little solder-starved. I'd touch those up a bit.

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phild13
 
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Re: Tube not lighting

Post by phild13 »

The tube header is soldered onto the tube board backwards. Bill can tell you what you need to do from this point forward.

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Re: Tube not lighting

Post by adafruit_support_bill »

Well spotted PhilD. I was focusing on the low boost voltage.

A reversed header can be fixed with some patience. If you can get access to a hot-air soldering station, you can probably get it off intact. Otherwise, I'd de-solder it pin-by-pin (you can just pull them out through the plastic spacer). You can clean up any stray solder with some solder wick and/or a solder-sucker. Then replace the header with a piece of 2x right-angle header.
https://www.adafruit.com/products/1541

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