Tips on troubleshooting board PCB

Discussion for purchasers of our original IN-7 Nixie chessboard
Mitb
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Tips on troubleshooting board PCB

Post by Mitb »

First of all I am working with the original PCB design.

So I successfully completed the three blank board PCBs without issue and then turned my attention to the partially completed board. When it came time to do my initial power test while assembling I got 0.11 mA on the series test. This hasn't happened before on any of the other boards, and I can't see any bridges, whiskers, mustaches, etc that could be causing a short. I tested the continuity as best I could, but I thought I would ask and see if that reading is an indicator of anything for you. Also what would be my best course of action at this point?
Tony
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Re: Tips on troubleshooting board PCB

Post by Tony »

If the 2R2 resistor is OK it might be a bad connection on the coil wires. What are the voltage readings round the microcontroller diodes?.
Mitb
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Re: Tips on troubleshooting board PCB

Post by Mitb »

The resistor is good and two of the diodes measure 46mV and one is around 60mV. The last one seems to steadily increase while I am reading it where as the first two sit steady.
Tony
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Re: Tips on troubleshooting board PCB

Post by Tony »

What is the voltage at each end of the 1k5 resistor?.
Mitb
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Re: Tips on troubleshooting board PCB

Post by Mitb »

It is showing 0mV.
Tony
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Re: Tips on troubleshooting board PCB

Post by Tony »

Are you sure the 2R2 is OK, do you have 12v at both ends?.
Mitb
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Re: Tips on troubleshooting board PCB

Post by Mitb »

Sorry about the deal getting back to you. I had to get a new fuse for my multimeter. I did recheck the 2R2 resistor and you are right, it is showing 0 volts.
Tony
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Re: Tips on troubleshooting board PCB

Post by Tony »

Did replacing it help?.
Mitb
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Location: California
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Re: Tips on troubleshooting board PCB

Post by Mitb »

Yes replacing it helped but now when I run it through series to check the amps, I get .7amps and I begin to smell something burning :-(

On my next day off I am going to recheck the backside for any bridges. Any other advice for me?
Tony
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Re: Tips on troubleshooting board PCB

Post by Tony »

If it still has only one coil on, disconnect it. If it has more added now, quickly check the voltage drop across each of the 6r8 resistors, that should show which pair of transistors are in trouble.
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