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24 comments
Anonymous Poster #1

Numbers are Missing in the Digital Clock

06/24/2011 8:26 AM

How to fix a digital clock where the numbers is not fully shown or missing?

I cannot read the full number in the time row. Other parameter are normal on the screen.

As attached you can see that.

I have checked all the connection even re soldered. Also cleaned with electronic component cleaner. But problem is not resolved yet.

What can be the problem. Why only time numbers are missing and other like Temp and humidity numbers are showing normal.

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#1

Re: Numbers are Missing in the Digital Clock

06/24/2011 9:00 AM

I don't know if you've covered everything here. Maybe it will help.

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Anonymous Poster #1
#2
In reply to #1

Numbers are Missing in the Digital Clock

06/24/2011 11:42 AM

Thank you for your Quick Reply.

But my clock is a portable digital clock. Whatever you said is for integrated digital clock in a bike where my clock is a table top clock.

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#3
In reply to #2

Re: Numbers are Missing in the Digital Clock

06/24/2011 12:20 PM

Sorry. I assumed that LCD's were all fairly similar.

The fixes for them are. Lots of google hits.

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#4

Re: Numbers are Missing in the Digital Clock

06/24/2011 2:29 PM

Check after dissasembly if the LCD is 'connected' to board via a rubber band with embeded conductive carbon stripes. If yes clean LCD, rubber and board with Isopropanol, dry and reassemble. Verify rubber is properly aligned, seated and depressed evenly between board and LCD (may have been loose). If it's a fixed connection instead of rubber, just go to recycle bin. S.M.

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#8
In reply to #4

Re: Numbers are Missing in the Digital Clock

06/25/2011 6:22 AM

GA

That's my take too.

They are a bugger to clean and re-install and it must be done with surgeons gloves on so that no grease from fingers gets on it.....a box of a hundred surgeons gloves costs here about $3.00.

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Anonymous Poster #1
#10
In reply to #4

Re: Numbers are Missing in the Digital Clock

06/25/2011 9:13 AM

Hello Simplemind.

Yes you are 100 % right, LCD board is connected via a rubber band with conductive carbon stripes. I have also cleaned it with CRC for electronic component. But still as shown in picture only Time Display is not proper. all other LCD ROW display are normal.
Is there any other option to replace this rubber band ?

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#11
In reply to #10

Re: Numbers are Missing in the Digital Clock

06/25/2011 9:34 AM

What is CRC?

If it is contact cleaner, it contains lubricants, not good.

Flip the strips around, if the same segments are defective, the strips are not at cause.

Clean all surfaces with IPA (isopropyl alcohol) and swab.

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Anonymous Poster #1
#12
In reply to #11

Re: Numbers are Missing in the Digital Clock

06/25/2011 9:48 AM

Hello gigaconcept.com

CRC is a electronic component cleaner for live circuits and it is non lubricating type.

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#5

Re: Numbers are Missing in the Digital Clock

06/24/2011 10:35 PM

The segments are fed voltage via a multiplexing circuit that is routed from the circuit board to the LCD through a Zebra Strip

This must be in uniform contact with both the circuit board and the LCD and usually has some tension mechanism. If the tension has failed, some parts of the zebra strip will not make contact = your problem

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#6

Re: Numbers are Missing in the Digital Clock

06/24/2011 11:46 PM

Replace the zebra connector. (LCD displays are mostly disposable type, though.)

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#7

Re: Numbers are Missing in the Digital Clock

06/25/2011 12:59 AM

The fix is simple. You have already re-soldered and cleaned. That didn't fix it. Now place the clock in a sandwich bag, along with a tablespoon of rice, and put it in the freezer.The rice will keep moisture from forming on the glass.

Now, go to the store, and buy a new clock.

When you get home, take the bag containing the rice and the defective clock and chunk it into the garbage can.

Enjoy your new clock.

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Anonymous Poster #1
#9
In reply to #7

Re: Numbers are Missing in the Digital Clock

06/25/2011 9:10 AM

Hello LYN,

I was just expecting you to be here. You can start your business in asian country dear. You are so creative in making ice foods.

So leave this and start your food chain because you can serve variety of dishes with electronics waste. That will even save e-waste on earth also.

I hope you will appreciate my compliment for your future career.

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#13
In reply to #9

Re: Numbers are Missing in the Digital Clock

06/25/2011 10:22 AM

Don't be an "A***Hole" with such comments, made anonymously.......make them under your log-on name if you are any sort of a human being at all.....or simply ignore the comments if you don't like them!!!

I believe it was meant a) as a joke and b) meaning its probably not worth the effort of fixing......he could be right!!

At least that is how I took it.....I am sure I am not alone......

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#17
In reply to #13

Re: Numbers are Missing in the Digital Clock

06/25/2011 6:00 PM

Hi, Andy,

Nope, you're not alone. The part about the rice had me thinking "what the #*@&...?", then I read the rest of Lyn's post and started laughing. AP#1 just doesn't 'get' the concept of sarcasm. It's an acquired skill, after all...

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#19
In reply to #17

Re: Numbers are Missing in the Digital Clock

06/26/2011 3:35 AM

LOL!!

Well put!!

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Anonymous Poster #1
#18
In reply to #13

Re: Numbers are Missing in the Digital Clock

06/26/2011 12:58 AM

Hi Andy..

I am here for solutions not for comments like you and your dearest one made on this forum. So be careful about what you wrote ? If you are so intelligent in providing solutions or guiding in the problems then why are wasting time by thinking this kind of non sense statements.

I have not invited you to answer for my problems. So many answered here and i did that thing to fix my device. Nobody comments except both of you.

So don't waste you time by making foolish jokes.

Anyway thank you for everything

have a great time.

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#20
In reply to #18

Re: Numbers are Missing in the Digital Clock

06/26/2011 4:37 AM

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#14

Re: Numbers are Missing in the Digital Clock

06/25/2011 1:19 PM

One of the segments of the clock's 7-segment LCD display may have gone bad? And /or the the corresponding segment transistor driver that turns that particular segment to go either ON or OFF state is also bad? Either way, it is not worthwhile repairing /wasting time for, since a comparable, cheaper replacement clock is easier to get!

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#15

Re: Numbers are Missing in the Digital Clock

06/25/2011 2:50 PM

Obviously one or more parts are malfunctioning. Replace one at a time until clock is fixed. If this doesn't work then do what Lyn said.

Why did nobody suggest the display chip to be replaced?

Why did the OP not think of it himself/herself?

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#16
In reply to #15

Re: Numbers are Missing in the Digital Clock

06/25/2011 3:20 PM

most cheap clocks like this are run by a single chip, have a minimum parts count, and either use the 50/60 Hz line as a time reference, and you solder together sets of pads to choose 50/60 Hz or have a 32 Khz crystal for a timebase, some have a trimmer capacitor, others are laser trimmed and are expected to maintain time within limits with temperature compensated parts. They usually mount on a circuit board and are encapsulated with a drop of epoxy.

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#21

Re: Numbers are Missing in the Digital Clock

06/26/2011 7:47 AM

I've opened up quite a number of devices that use LCD for the same reason that segments are missing. The culprit will always be the 'zebra strip' or zebra connector or carbon stripes'. More often than not, when I reassembled it after cleaning, different set of segments would be missing. It's just difficult to make a fairly good contact with the terminals, especially, when the strip is deformed.

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#22

Re: Numbers are Missing in the Digital Clock

06/26/2011 9:36 PM

Spend the $10 - Buy a new Clock...

Not worth the time & trouble, given the low percentages of successful repair.

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Anonymous Poster #1
#23

Numbers are Missing in the Digital Clock

06/27/2011 11:34 AM

Dear all,

Thank you very much for your kind support and replies for my problem. by replacing the conductive carbon rubber stripe my digital clock is working normal now. All the digits are clear.

Thanks again for your kind support.

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#24
In reply to #23

Re: Numbers are Missing in the Digital Clock

06/27/2011 4:22 PM

Did you just clean and rebuild, or did you find a source for the elastomeric conductive ""zebra strip"? If you found a source for this material, I would like to add that to my list of suppliers. I have a hobby of "consumer" electronics repair, and I've never tried to buy a new strip, thinking they would be hard to find.

Tom D.

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Users who posted comments:

Andy Germany (4); Anonymous Poster (6); aurizon (2); gigaconcept.com (1); kramarat (2); lyn (1); OldTechNewToys (1); SimpleMind (1); spooklight (1); StandardsGuy (1); sulat (2); tdesmit (1); vsar (1)

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