Ice Tube Clock - no display - voltages normal without VFD
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Ice Tube Clock - no display - voltages normal without VFD

by cvilas on Sun Nov 18, 2012 3:10 pm

I just finished building the ice tube clock kit following the instructions here.

Voltage test 1 passes - input to the 7805 is 9V and the output is at 4.9V.
Voltage test 2 passes - 56 volts at D3 (striped end) without IC2 (VFD driver) plugged in and 14.2 volts with the driver in the socket. (VFD not plugged in at this point)

After completing the main board, without the VFD board plugged in, voltages at the source and drain of Q4 is about 4.7 volts. I believe this is correct as well.

However, with the VFD board plugged in, I get no display, and the following are observed:
(a) Voltage at D3 now falls to about 8 volts
(b) Voltage at Q4 Drain terminal falls to about 2.7 volts

I observed that there is no resistance between VBIAS and GND pins of the VFD (continuity test with my multimeter beeps). This seems strange. Is the VFD shot? A few pictures are in the album below. Any tips appreciated.

https://picasaweb.google.com/101913593427540595709/IceTubeClockTroubleshooting?authkey=Gv1sRgCNDo9_Cv25G3Jw


thanks
Vilas
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Re: Ice Tube Clock - no display - voltages normal without VFD

by adafruit_support_bill on Sun Nov 18, 2012 4:56 pm

I observed that there is no resistance between VBIAS and GND pins of the VFD (continuity test with my multimeter beeps).

What is the actual resistance measurement? This is a heater wire, so the resistance is fairly low.
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Re: Ice Tube Clock - no display - voltages normal without VFD

by cvilas on Sun Nov 18, 2012 5:14 pm

I am seeing less than 1 ohm
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Re: Ice Tube Clock - no display - voltages normal without VFD

by adafruit_support_bill on Sun Nov 18, 2012 7:44 pm

A typical resistance value would be in the range of 14 ohms. This is low enough for a continuity test beep on most meters.

Test again. If you are still seeing less than 1 ohm, contact support@adafruit.com with a link to this thread for a replacement tube.
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Re: Ice Tube Clock - no display - voltages normal without VFD

by cvilas on Wed Nov 21, 2012 4:22 am

I bought the kit from http://phenoptix.com/ in the UK and they have kindly agreed to send me a replacement tube. Thanks for your help.
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