Author Topic: How to attach a digital micrometer LCD screen to its PCB  (Read 395 times)

Offline j1312v

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How to attach a digital micrometer LCD screen to its PCB
« on: June 11, 2017, 02:31:58 PM »
Hi all,

Had the bad luck of buying a second hand Tesa digital micrometer from eBay that after a few weeks stop working, so in hope of finding something blindingly obvious I decided to open it. :dremel:

After a quick inspection the problem was as indeed obvious, the LCD screen got detached from the PCB. :palm:

Unfortunately the technique requited to fix it is unknown to me and after researching in the internet just found a couple of very sketchy videos in youtube. :loco:

Does any us you wise madmodders know I can re attach the LCD screen to the PCB?

Best,

Joe

Offline awemawson

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Re: How to attach a digital micrometer LCD screen to its PCB
« Reply #1 on: June 11, 2017, 03:18:37 PM »
Usually there is a contact strip of conductive elastomer  for the contacts, and a clip to hold it slightly compressed.
Andrew Mawson
East Sussex

Offline PekkaNF

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Re: How to attach a digital micrometer LCD screen to its PCB
« Reply #2 on: June 11, 2017, 03:23:33 PM »
You probably know that it does not need to be qlued or such.

That green "zebra" is elastic conductive connector and it makes the contact between LCD and PCB. It does needs a careful mechanical aligment to work.

So, what seems to be the problem originally? Zebra related symptoms are erratic display or missing elements, hardly never display has nothing in it.

Was it like this?
https://youtu.be/MTulo_SIE6E


Pekka

Offline j1312v

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Re: How to attach a digital micrometer LCD screen to its PCB
« Reply #3 on: June 11, 2017, 04:48:07 PM »
No clip I'm afraid Andrew, very weak design IMO from such a prestigious brand.

First I lost the first digit and then all of them Pekka and yes I need to carefully aline the conducting strips in both parts.

The videos that I found shows a Chinese guy at a repair/rework department attaching lcd screens to pcbs using a special tape but it's not clear what exactly is and how it works.

I'm hoping that PK may know the technique.

Cheers

J

Offline seadog

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Re: How to attach a digital micrometer LCD screen to its PCB
« Reply #4 on: June 11, 2017, 05:48:37 PM »
They can be very temperamental too. I had a Beckman DMM that had display problems. It was dismantled, the contacts cleaned with a fibreglass brush and then all contact surfaces cleaned off with IPS. I reassembled it and it would not work at all. Stripped and checked the surfaces again, all seemed OK. Reassembled, nothing  :bang: I left it in a box for a year and then decided to throw it out but thought I'd put it back together again just to see if anything had changed. It worked and is still working two years later  :Doh: 

Offline Pete W.

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Re: How to attach a digital micrometer LCD screen to its PCB
« Reply #5 on: June 12, 2017, 05:30:54 AM »
I was going to plead with Joe to reduce the size of his photo.  Then I discovered that I can navigate around the expanded photo using the arrow keys!

 :Doh:   :Doh:   :Doh:   :Doh:   :Doh:   :Doh: 
Best regards,

Pete W.

If you can keep your head when all about you are losing theirs, you haven't seen the latest change-note!

Offline awemawson

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Re: How to attach a digital micrometer LCD screen to its PCB
« Reply #6 on: June 12, 2017, 12:02:47 PM »
Returning to the O/P's initial question, is the LCD not trapped by the case against the conductive pad and PCB, and thus effectively the case is in this example the 'clip' ?
Andrew Mawson
East Sussex