Troubleshooting

[Tony]

Check your multimeter fuse and the meter is working OK. Check the power supply is producing 5V and try another USB lead just in case it's faulty if it's the type with a plug-in lead. There is so much connected to the 5V line there should be some reading if power is getting to the board.

Hi i have just recently received my thermometer from think geek and I have assembled the PCB up to the first stage of testing and when I put my multimeter across R28 I get no reading set to the 1A scale. I have inspected the board for dry joints and bridges, its all good no bridges or dry joints found.

Here are pictures of the front and back of the pcb http://imgur.com/a/2zGXg

Thanks any help would be appreciated.

[Moharmate]

Thank you I was previously checking with the three meters that I have and didn't even think that the fuses could of blown on all of them, made a make shift fuse and checked and all is working now.

thanks.

[austinv11]

Hello, I have recently received my kit (latest available version), but I have noticed that I am missing the 100R resistors? Can I have the exact specifications for them, to see if I could buy them at my local RadioShack or something?

[Tony]

Not there at all?. Sorry I don't usually miss a whole component strip.

They're just plain 1/4 watt 5% so won't be hard to find, anything up to 150R will work.

[austinv11]

No problem, I might have just lost them, but thanks!

[nich009]

I have they DIY Nixie tube thermometer. Unfortunately I put it together and its not working. the tubes flash a bit, more if I blow around the base of each tube. The LEDs also will not light. I haven't found any solder bridges. I think I may have gotten the surface mount chip too hot. Any help would be much appreciated. Also checked the voltage between the ground the middle pin and pin 3 and got a reading of 4.7 volts. Between ground and pin one 2.59 volts. I'm using the wrong fuse in my multi meter to check the current i should be using a .3 amp 250v fuse but i put in a .25 amp 250v fuse. I got a reading of 22 mA across r28.

[Tony]

This one could be tricky...
The flickering tubes and no LEDs mean the HV is working but the controler isn't sending anything to them. Did the LEDs work when it was tested before fitting the tubes?. If you're sure the SMD IC has been damaged just remove it for now and make sure none of the tracks there are bridged - it will still work using the DHT11 sensor.
What would help is the current reading in series with R28 - you really need a meter that can handle up to at least 500mA, preferably 0-1A.

[nich009]

This one could be tricky...
The flickering tubes and no LEDs mean the HV is working but the controler isn't sending anything to them. Did the LEDs work when it was tested before fitting the tubes?. If you're sure the SMD IC has been damaged just remove it for now and make sure none of the tracks there are bridged - it will still work using the DHT11 sensor.
What would help is the current reading in series with R28 - you really need a meter that can handle up to at least 500mA, preferably 0-1A.

The LEDs did not work before fitting the tubes. I removed the SMD IC and the tubes still flicker no LEDs though. I could try getting into one of my campus engineering rooms and use a better voltmeter.

[Tony]

Could you measure the voltage across one of the LEDs? - it should change every few seconds depending on display mode. Also any sign of IC1 or 2 getting hot?.

[nich009]

Could you measure the voltage across one of the LEDs? - it should change every few seconds depending on display mode. Also any sign of IC1 or 2 getting hot?.

D2,3,4 go between 0v and .55v. D5,6 go between 0v and .45v. Neither of the ICs are getting hot.