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phoneguy

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Posts: 2
Reply with quote  #1 
I recently acquired one of your Audio DTMF Decoder kits (kit 153) and I'm having an issue with it that I'm hoping you might have some insight to.

I have checked and rechecked all solder connections, voltages at the specified points on the board. My issue is; I can not get the display to show anything but six black squares,starting at the left edge. No amount of adjustment of the VR-1 trimpot will lighten the display enough to show "Ready".
I did find one trace bad on the board at the ground trace for the power regulator but repaired that and have 5.0 v everywhere it's supposed to be.

Any suggestions you can think of would be greatly appreciated.

Thanks in advance,


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Frank

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Posts: 1,905
Reply with quote  #2 
Hi,

Only 2 problems that I can think of:

1. Board assembly error, either incorrect component placement or bad solder joint.
2. The supplied microcontroller has not been programmed correctly.

The first problem can be checked by doing a thorough visual inspection of the board. If able please upload photos of both sides of the board for me to look over. Please make sure any photos are clear and in focus. They should also be taken maximum zoom possible but still showing the whole board.

The second problem is unlikely but I can only check if I have the board here. Up to you if you want to send to me or not. I will not charge for any repair - just return postage. I am in Melbourne, Australia.

Question:
Are you using the onboard microphone or the telephone line for testing?

Frank
phoneguy

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Posts: 2
Reply with quote  #3 
Thanks for responding so quickly, that is greatly appreciated.
Tested all solder connection, all leads have continuity to board.
Instructions state that “ready” should show up on the right side of screen.
Holding the board with power connector at lower left, I get 6 blank squares at the left edge of the screen, not right.
I have not tested with either line or mic as I couldn’t get past this initial point of verification.
I’ll consider sending you the board, maybe retest everything again . . .

Thanks in advance,
Pete (Phoneguy2400)

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