Ice Tube Clock has no Display
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Ice Tube Clock has no Display

by fergusonjp on Sat Dec 29, 2012 4:28 am

I am at the installing the max6921 chip stage of putting together my Ice tube clock purchased from Adafruit and have hit a snag. I have just installed the Max6921 chip and plugged in the VFD and I have no display. Prior to installing the chip I had the following voltages. Voltage regulator input 8.85Vdc, output 4.97Vdc. 56.6Vdc at striped end of D3. The three leads on transistor Q3 are 4.67Vdc for the two outside leads and 0.3Vdc on the center lead. After installing the Max6921 chip with dot toward buzer I got the following voltages: Voltage regulator input 8.13Vdc, output 4.97Vdc. 8.40Vdc at striped end of D3 and transistor Q3 had 0.47Vdc on lead nearest outside edge of circuit board, 0.003Vdc on center lead and 4.60Vdc on inside most lead. Curved side of transistor Q3 is toward the striped end of D5. When I plug in the VFD nothing lights up. I am only seeing very low voltages on the VFD wires (around 0.1Vdc). I put the Max6921 chip in upside down initially and powered it, realized my mistake and de-energized and removedand re-installed correctly. I'm afraid that I have damaged it. I would be willing to pay for a replacement.
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Re: Ice Tube Clock has no Display

by adafruit_support_bill on Sat Dec 29, 2012 7:26 am

If you remove the Max6921 chip, do the boost voltages go back to their former levels?
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Re: Ice Tube Clock has no Display

by fergusonjp on Sun Dec 30, 2012 3:05 am

Yes. I have installed and removed the chip several times and the voltages are consistent for when installed and when removed.
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Re: Ice Tube Clock has no Display

by adafruit_support_bill on Sun Dec 30, 2012 8:21 am

I am only seeing very low voltages on the VFD wires (around 0.1Vdc).

I suspect that the VFD chip is dead. The signals on these wires are best observed with an oscilloscope, but most multimeters will read it as a voltage higher than what you are reporting.

We do not have the chips available for individual sale, but they are available direct from Maxim as well as from other suppliers. http://www.ladyada.net/make/icetube/parts.html

If you post photos of the front and back of the board we can check over the rest of your assembly too.
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Re: Ice Tube Clock has no Display

by fergusonjp on Sun Dec 30, 2012 8:28 am

Do you know a supplier that I can obtain individual quantities from. I was on the Maxim site and it looked like they wanted me to buy a thousand.
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Re: Ice Tube Clock has no Display

by adafruit_support_bill on Sun Dec 30, 2012 8:37 am

Maxim used to sell individual chips. And some customers were even able to get free samples: viewtopic.php?f=8&t=14862
Failing that, there is always findchips.com: http://www.findchips.com/avail/?part=max6921
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Re: Ice Tube Clock has no Display

by fergusonjp on Sun Dec 30, 2012 9:13 am

Ok. I found the Mouser has Max6921AQI + available in individual quantities. Is this the correct model or a suitable match?
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Re: Ice Tube Clock has no Display

by adafruit_support_bill on Sun Dec 30, 2012 9:17 am

Yes. The AQI is the PLCC packaged version we ship with the kit.
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Re: Ice Tube Clock has no Display

by fergusonjp on Sun Dec 30, 2012 1:05 pm

Do you know what the '+' after the part number means?
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Re: Ice Tube Clock has no Display

by adafruit_support_bill on Sun Dec 30, 2012 1:48 pm

The + indicates lead-free packaging.
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