Trouble Shooting Eggfinder LCD Build

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TXWalker

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I just finished building the Eggfinder LCD. Everything seemed to be ok until I tried to power the unit up. All I get is solid black squares across the LCD display, no beeps from the buzzer either. I went back and touched up all the solder joints thinking I might have a bad connection. Still no signs of life. I even hooked up the data cable to the USB port on my PC. I can see “prolific” on COM3 is active.

Any suggestions what to try next?

Thanks, Pete
 

rockladen

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You need to adjust the contrast. It's marked on the board, and it's that little white round dial. Adjust it with a small flat head driver. Mine's was like that and took me a couple days to figure it out.
 

TBob

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I had this same issue with a fresh one earlier this year. I contacted Cris and he suggested reflashing the software. It does take a data cable to do this. Worked like a champ. I'll see if I can find the procedures.
 

TXWalker

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Cris, That didn't work. I have not been able to communicate with the device to update the firmware.
 

tOD

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Cris, That didn't work. I have not been able to communicate with the device to update the firmware.
Did you try the suggested contrast adjustment? I had to do it with mine.
 

g.pitts

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Cris, That didn't work. I have not been able to communicate with the device to update the firmware.
Do you have a voltmeter? If so, measure your input voltage by putting your red (+) probe on the + PCB pad and your black (-) probe on the - PCB pad. What do you read for that voltage? Then do the same with 5V and 3.3V and let us know what you see for each of the two voltage rails. They should be within 5 percent or so of their expected values.
 

cerving

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Check your solder joints on the regulators... they look pretty thin from the pictures.
 

Voyager1

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Is the RF module on the LCD unit flashing in response to an Eggfinder TX unit? This probably won’t help you with the current issue, but it will indicate something is working.
 

Voyager1

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Check the solder joints around the 10k resistor that is adjacent pins 3 and 4 of the processor. I’m not sure, but it appears that the outer lead might have a solder bridge to the board. If so, that might be holding the processor in reset. It could just be an untrimmed length of lead - it’s a little hard to tell in the image.
 
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Voyager1

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There might be a couple of other spots to check as well. Probably nothing, but in the image they look a little sus in the available lighting and slightly blurred image when zoomed in. I'm probably just seeing bent untrimmed leads and shadows. Double check all solder joints for potential bridges. Also, the solder joints along the RF module, are they OK?

It appears that the processor is not communicating with the LCD module judging by the single line of dark character blocks. In fact, the processor doesn't appear to be booting up at all!

Have you adjusted the LCD contrast as suggested above? Are there any other symptoms that you have noticed? As suggested above by the others, if you have a multimeter check all the voltages from the 3.3V and 5V regulators and trace them around the board.

Also, again if you have a multimeter, with the power off, check across the resistors for correct values and no shorts. Then, when powered up, check the voltage on pin 1 of the processor - I believe it's the RESET pin and it should be high, not at 0V.

LCD Rx Brd.jpg
 

TXWalker

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Thanks guys for the advice. I've gone over the solder joints with a magnifying glass and don't see any bad solder joints. The dark joints Voyager is highlighting have a little flux residue. It cleaned off with IPA. I played with the LCD contrast, it goes from all black to all clear as I adjust the contrast. No signs of life on the processor of other modules. I agree the processor is not booting.

I know when I'm in over my head. I packaged up everything and sent it to Connor McGrath to look at.

Thanks, Pete
 

TXWalker

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I thought I should give a final update on my Eggfinder LCD build. I was unable to get the unit to wake up after assembly so I shipped it to Connor McGrath to see if he could figure out what was wrong. He said he could not get it working either. All the solder joints looked OK but the main processor was not working. Connor shipped it back to the factory and sure enough the processor was bad. Eggtimer replaced the kit and I had Conner assemble the new kit. Today I was able to finish the assembly and try the receiver out with the TX unit I had built previously. Hurray! Everything is working perfectly. I had five satellites and "found" the TX unit in the back yard. I can't wait to try it out in a rocket!

I'd like to give a big shout-out to Connor for all his help diagnosing the issue. Also to Eggtimer for replacing the unit no questions asked.
 
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