I have a problem with my 1st project build, a clock

Thread Starter

John O'C

Joined Mar 22, 2017
68
I have a problem with my 1st project, which I have illustrated with the photo below.

As you can see, only one of the 7 segments is lit. (I suppose one is better than none:eek:)

every newcomer would like the encouragement of a working project I think and I am no different.
I would really appreciate some help to get a fully functioning clock, my fault finding skills are fairly limited at the moment, so I won't mind being treated as a simpleton, when you respond.

Thanksupload_2017-3-22_17-42-7.png
 

AnalogKid

Joined Aug 1, 2013
9,262
Based on the information you have provided, what do you think a stranger 1,000 miles away can do with no test equipment, no view of the wiring, and no schematic. If you don't want to be treated as a simpleton, Think.

In electronics anything, a schematic is everything. Even if it is perfect, seeing it rules out a ton of stuff that would take 50 postings to work through.

Next, photos. We've all wired up stuff that wasn't pretty, so no one rational will dis you for appearance. If the wiring is overly confusing, you'll get pointers on how to clean it up.

ak
 

dl324

Joined Mar 30, 2015
12,873
Welcome to AAC!
I would really appreciate some help to get a fully functioning clock, my fault finding skills are fairly limited at the moment, so I won't mind being treated as a simpleton, when you respond.
As mentioned, we need a schematic showing how things are connected; at least how they're supposed to be.

We also need information on the display. Is it common cathode or common anode? Is it multiplexed?

What is the power source?
 

Thread Starter

John O'C

Joined Mar 22, 2017
68
I built it from a kit.
I was advised to use a kit to begin with (soldering practice et cetera). The kit is here…

https://www.amazon.co.uk/DIY-Clock-...ital+LED+Large+Screen+Display+Clock+kit+Green

Is it multiplexed?
Sorry, I don't know/understand the question

Welcome to AAC!
As mentioned, we need a schematic showing how things are connected; at least how they're supposed to be.
Photo attached

What is the power source?
It's a USB cable
upload_2017-3-22_18-47-58.png

upload_2017-3-22_18-52-2.png
 

dl324

Joined Mar 30, 2015
12,873
The link doesn't work for me.
Sorry, I don't know/understand the question
The displays are common anode and are being multiplexed.

What digits are supposed to be displayed? Have you checked for any solder bridges?

The pictures would be more useful if you posted clearly focused images of reasonable size. The component diagram might also be helpful.
 

Thread Starter

John O'C

Joined Mar 22, 2017
68
bertus, it is correct, I believe. Something to do with displaying different information.
INSTRUCTIONS: "The 3rd digit tube must be installed backwards"

Hello,

You have soldered the third digit the wrong way around.
Look at the decimal point.

Bertus
 

Thread Starter

John O'C

Joined Mar 22, 2017
68
My apologies for the quality of the pics., but thanks for the help. I would like to resolve it though.

Hello,
Is the cristal (Y1) clear from the PCB?
The metal housing could cause a short on the PCB.
Bertus
It is, by about 2mm

I have checked the soldering, no obvious solder shorting, but I am new to this.

upload_2017-3-22_19-32-23.png
 

RichardO

Joined May 4, 2013
2,271
It looks like there is a programming connector on the board. Did the microcontroller (U2) come programmed or did you program it? It looks like the programm is not working.
 

bertus

Joined Apr 5, 2008
21,371
Hello,

It looks like the big chip is the wrong way around.
The gap is on the right side of the drawing, but on the left on the PCB.
I hope the chip survived.

Bertus
 

AnalogKid

Joined Aug 1, 2013
9,262
To me it looks like the indent is on the left, which is consistent with the locations of the pullup resistors and the digit drivers.

Segment B is stuck on all displays, so that's probably a clue. Pin 6 on the displays, pin 20 on the uC. The soldering looks ok but their might be a tiny crumb somewhere. All displays show it, so the multiplexed digit drive probably is ok.

Was the uC plugged in backwards accidentally?

ak
 

dl324

Joined Mar 30, 2015
12,873
The power pins must have been arranged so backwards insertion didn't forward bias a parasitic diode and destroy the device.

Count your lucky stars and be more careful in the future.
 

Thread Starter

John O'C

Joined Mar 22, 2017
68
So….

We have gone from 1% to 99% Success.
Can we get to 100%?

upload_2017-3-22_20-38-57.png

Clue: It should read 20:28

How can I resolve this problem?
O.K. The middle segment is missing (left hand side)
 
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