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Clock Kit worked but now don't work...
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Please be positive and constructive with your questions and comments.

Re: Clock Kit worked but now don't work...

by hinermad on Sat Sep 19, 2009 9:35 am

Sometimes the parts themselves can be bad. I had a radio transmitter kit once that came with a shorted ceramic capacitor that caused symptoms similar to what you're seeing.

Have you tried feeling around for any hot components other than the fuse? If something is hogging the current it may be getting warm enough to feel.

If you haven't already, I suggest unsoldering the parts you installed since your last good test and see if the problem goes away. If it does, try re-installing them one at a time and test in between.

Dave

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Re: Clock Kit worked but now don't work...

by tlavite on Sat Sep 19, 2009 11:36 am

ki4mmm wrote:Did you check for solder bridges *on top* of the board? There is quite a bit of solder coming through several holes in what is visible in the picture - how about at the legs of the transistor, or the other parts that went on when the problem manifested itself?



yup i looked under and around all the parts, around every pin, and solder joint... i have a feeling its a bad part but I don't know what part would have just up and decided to quit working.
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Re: Clock Kit worked but now don't work...

by tlavite on Sat Sep 19, 2009 11:39 am

Hinermad wrote:Sometimes the parts themselves can be bad. I had a radio transmitter kit once that came with a shorted ceramic capacitor that caused symptoms similar to what you're seeing.

Have you tried feeling around for any hot components other than the fuse? If something is hogging the current it may be getting warm enough to feel.

If you haven't already, I suggest unsoldering the parts you installed since your last good test and see if the problem goes away. If it does, try re-installing them one at a time and test in between.

Dave




I honestly think its a bad part but idk how or what part would work one minute and then just stop the next... I have also unsoldered the parts that i installed in the last step and still the same results. I have also done as you said and felt around the board for hot warm components and the only one is the fuse. I'm at a loss.
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Re: Clock Kit worked but now don't work...

by tlavite on Sat Sep 19, 2009 12:52 pm

Okay so with further investigation i can now say that when plugged in the regulator does get hot. I took the regulator out to see if that was shorting and the fuse still gets hot.


Okay i might be entirely wrong here but if there is a short somewhere from positive to ground with a continuity tester if i place one probe on ground and then one on the fuse or on any other positive line in the circuit shouldn't i get continuity as in there is a short from positive to ground?

example i placed one probe on the ground pin of the regulator then the other probe on the positive pin of the power jack and got no beep... i also tested from ground to the fuse and got nothing... so idk how or where there is a short. I am asking this question once again... if it is not a short what are the other possible things that could have happened? what part might have gone bad that could be causing this fuse to activate?


I've pretty much lost all hope on getting this to work... i feel as if i have just threw away 70 bucks
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Re: Clock Kit worked but now don't work...

by tlavite on Sat Sep 19, 2009 1:38 pm

Okay so i was testing the capacitors and capacitor C4 has continuity across its pins is that correct? or should i not have continuity on C4's pins?


EDIT: I give up on the clock, I have done everything i am capable of doing and i cant not find a single short... this sucks i just wasted 71 dollars.
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Re: Clock Kit worked but now don't work...

by hinermad on Sat Sep 19, 2009 2:45 pm

I'm only working from the schematics on the clock design page on Lady Ada's web site (which doesn't show the fuse at all - I've been assuming it's in series with D1). If you put an ohmmeter across C4 while it's in the circuit it may show some continuity because of the rest of the circuit. If it shows less that 30 ohms or so I'd suspect someting is shorted, but not necessarily C4. The only way to tell for sure if a cap is shorted is to remove it from the circuit and test it separately.

If you removed the regulator and the fuse still got hot that limits the search area because you've ruled out everything that uses 5V. About the only thing left is the 30 volt boost circuit. I'd start by removing Q2. If it's shorted or the gate (controlled by the BOOST signal) is stuck high, it'll suck current through L1 and cause the fuse to operate. If the fuse still heats up, remove D3 next. If you're still getting a hot fuse after that, I'd check C1 and C2 for shorting, and take a really hard look for shorts around the pads and traces by the power jack, fuse, and those caps.

Dave

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Re: Clock Kit worked but now don't work...

by tlavite on Sat Sep 19, 2009 2:58 pm

Hinermad wrote:I'm only working from the schematics on the clock design page on Lady Ada's web site (which doesn't show the fuse at all - I've been assuming it's in series with D1). If you put an ohmmeter across C4 while it's in the circuit it may show some continuity because of the rest of the circuit. If it shows less that 30 ohms or so I'd suspect someting is shorted, but not necessarily C4. The only way to tell for sure if a cap is shorted is to remove it from the circuit and test it separately.

If you removed the regulator and the fuse still got hot that limits the search area because you've ruled out everything that uses 5V. About the only thing left is the 30 volt boost circuit. I'd start by removing Q2. If it's shorted or the gate (controlled by the BOOST signal) is stuck high, it'll suck current through L1 and cause the fuse to operate. If the fuse still heats up, remove D3 next. If you're still getting a hot fuse after that, I'd check C1 and C2 for shorting, and take a really hard look for shorts around the pads and traces by the power jack, fuse, and those caps.

Dave



I removed all the electrolytic caps and tested them there perfectly fine. I will check Q2 and D3 which i think I've checked before but ill do again.
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Re: Clock Kit worked but now don't work...

by tlavite on Sat Sep 19, 2009 3:29 pm

Hinermad wrote:I'm only working from the schematics on the clock design page on Lady Ada's web site (which doesn't show the fuse at all - I've been assuming it's in series with D1). If you put an ohmmeter across C4 while it's in the circuit it may show some continuity because of the rest of the circuit. If it shows less that 30 ohms or so I'd suspect someting is shorted, but not necessarily C4. The only way to tell for sure if a cap is shorted is to remove it from the circuit and test it separately.

If you removed the regulator and the fuse still got hot that limits the search area because you've ruled out everything that uses 5V. About the only thing left is the 30 volt boost circuit. I'd start by removing Q2. If it's shorted or the gate (controlled by the BOOST signal) is stuck high, it'll suck current through L1 and cause the fuse to operate. If the fuse still heats up, remove D3 next. If you're still getting a hot fuse after that, I'd check C1 and C2 for shorting, and take a really hard look for shorts around the pads and traces by the power jack, fuse, and those caps.

Dave



I have removed Q2 fuse still gets hot. I then removed L1 and D3 and the fuse still gets hot. there are not shorts around anything that you mentioned to check... even though i have checked for shorts like crazy. IDK what to do i hate to remove everything from the board.
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Re: Clock Kit worked but now don't work...

by hinermad on Sat Sep 19, 2009 3:55 pm

Maybe the fuse itself is bad? I've never used one but I've seen other thermistor products get stuck at the wrong resistance (although usually because of being seriously overheated). I don't want to suggest jumpering out the fuse to see if the clock works, because if there is a different problem you'll have no overcurrent protection and you could damage something or cause a fire.

I just found the datasheet for the fuse. It says the resistance at room temperature should be between 1.83 and 2.75 ohms. That might be worth checking just to see if the fuse has failed.

Dave

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Re: Clock Kit worked but now don't work...

by ki4mmm on Sat Sep 19, 2009 4:56 pm

yup i looked under and around all the parts, around every pin, and solder joint... i have a feeling its a bad part but I don't know what part would have just up and decided to quit working.


There aren't many parts that were added after the test that worked (battery holder, diode, and switches). There is always a chance that there is a cold solder joint, that worked on the first test (I have had this happen more than once). Go over all of the joints with your soldering iron and reheat them. Even though they may look good, there are times when the leads of certain components just don't 'take solder' well (like those dull leads on the big diodes). Give each a good heating so that you see the solder liquify. Alternate which parts you are doing so you don't overheat the part (e.g., do one lead of a resistor, then a lead on another resistor, then come back to the other lead of the first resistor).

Don't give up, these things happen to all kit builders (even experienced) - I've had some that took me weeks to figure out.....
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Re: Clock Kit worked but now don't work...

by tlavite on Sat Sep 19, 2009 9:30 pm

Hinermad wrote:Maybe the fuse itself is bad? I've never used one but I've seen other thermistor products get stuck at the wrong resistance (although usually because of being seriously overheated). I don't want to suggest jumpering out the fuse to see if the clock works, because if there is a different problem you'll have no overcurrent protection and you could damage something or cause a fire.

I just found the datasheet for the fuse. It says the resistance at room temperature should be between 1.83 and 2.75 ohms. That might be worth checking just to see if the fuse has failed.

Dave



Well i removed the fuse and tested it and i am getting 4.8 Ohms out of it.
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Re: Clock Kit worked but now don't work...

by hinermad on Sat Sep 19, 2009 11:49 pm

That seems like it's close enough that it should work. I'm afraid I'm all out of ideas. The only other thing I can think of would be a short in the PC board itself. I've only ever seen that once where a board actually had a short circuit (as opposed to a layout error where traces were bridged). And even then it came from the board fabricator that way, it didn't develop a short after it was built and been operated.

I'm sorry, but I've got nothing else to suggest.

Dave

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Re: Clock Kit worked but now don't work...

by tlavite on Sun Sep 20, 2009 12:53 am

I know i am all out of ideas also... idk what to do... i feel as if i am out of luck..
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Re: Clock Kit worked but now don't work...

by tlavite on Sun Sep 20, 2009 2:40 pm

Is there anyway I can Send the board to adafruit and have you guys look at it? I can not find a single thing wrong with it. Not one thing I can guarantee that anyone who looks at this board will be mind boggled as to why it is not working. I hate to just be out 70 bucks it's a great kit and I wanna see it working but I feel as if I'm SOL and will have to buy another kit which I can't do.
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Re: Clock Kit worked but now don't work...

by adafruit on Sun Sep 20, 2009 4:38 pm

first off, put the fuse back in the board. that shouldnt be removed.
Now you say that you removed the buttons, diode and battery holder?
once you have removed those parts, unplug the tube (you did do that right?) and gently remove the microcontroller and display driver
THEN
Take a REALLY CLEAR AND LARGE PHOTO of your kit top and bottom
the photo should look JUST LIKE the ones on the website. Use good light and DONT use your cellphone camera.
its extremely unlikely that a part just 'failed', its also not the circuit board. so its the soldering or a part

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Please be positive and constructive with your questions and comments.