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LCR-T4 replacement display ideas wanted

Sidecar Bob

Dec 19, 2021
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Quite a while ago I ordered an LCR-T4 transistor/diode/capacitor &c tester. When it arrived the top left corner of the display was chipped and the top half of the display was blank. I received a working unit a few weeks ago so I do have one to use myself but I got thinking about whether the display could be replaced so I could give it to someone else.

I found the original display on Aliexpress but it is no longer available
https://www.aliexpress.com/item/32816995325.html?spm=a2g0o.seodetail.topbuy.1.1ea15721fEnQ7i

I found this display that looks the similar to me but I know very little about these things
https://www.aliexpress.com/item/32899426354.html

I also found this article about upgrading the display but he doesn't give many detains and I have no idea how to connect the display he used
http://eessential.blogspot.com/2018/12/lcr-t4-transistor-tester-display-upgrade.html

Am I pursuing untamed aquatic birds again or is this something worth attempting?
 

Bluejets

Oct 5, 2014
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Looks like an Oled display...even if compatible, soldering of that very fine pin pitch would be normally a solder flow robot job.
Good luck with a 40w bench iron.
 

Sidecar Bob

Dec 19, 2021
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Do you mean the original type display or the one Eesential used?

The original one plugs to a connector on the board...
 

kellys_eye

Jun 25, 2010
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You need to check all the datasheets for 'any' 64x128 dot matrix display and see if the various data lines match the existing display. I suspect that most 'non-onboard-controller' displays will have similar if not identical connections - not necessarily in the right order though! - and that a replacement could be fitted. Something larger might also improve the usage.
 

Sidecar Bob

Dec 19, 2021
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The display has what I would call a flexible PCB (maybe there is a newer name for this?) that connects to the board plus a pair of leads for the LED. Looking behind the display from the end without unsoldering the LED leads on Monday I thought I was seeing the contacts on the flexible plugged into a low profile set connector similar to ones I've seen inside laptops. Today I unsoldered the LED leads and as you can see the flexible PCB is soldered to the main board. I don't think unsoldering it and soldering on a new one would be beyond my abilities with my WTCPS soldering station and a small tip (old tech but still very good)
Display connector.JPG

I contacted the seller of the display that I thought looked similar (2nd link in post #1) and they said it will work with an LCR-T4. Now that I can see where it connects to the main board I can tell that it has the right number of pins and the spacing matches so I ordered one.

Oddly the one in the first link (available again) now shows a lot more than the required 14 pins so it won't work. Maybe it's a good thing I missed it.
BTW: Here is what the damaged display looks like
01 - Damaged display.JPG
 

Bluejets

Oct 5, 2014
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Whole thing is only $20 odd....better still, spend a bit extra ($30) and get one in a case.
 

Sidecar Bob

Dec 19, 2021
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It came to under $12 Canadian for the display & case and the tester would otherwise be scrapped so that's not bad.
 

kellys_eye

Jun 25, 2010
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Oddly the one in the first link (available again) now shows a lot more than the required 14 pins so it won't work.

The number of pins actually used is the same as the other device - it can probably be used but would require a lot of individual wires to be soldered between display and board.

As per the above, at $12 these are 'disposable' items and I have THREE (one in use - cased - two [actually ordered in error!] kept as spares). Not worth the effort and expense imho.
 

Sidecar Bob

Dec 19, 2021
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When I said "it won't work" I meant it cannot be a direct replacement.

$12 is what I paid for the replacement display and a case to mount the unit in, including shipping.
Complete units (tester + case) average around $20-30 Canadian depending on where you buy them. I paid about $20 for the first one on eBay 6 months ago but the same item from the same seller is now almost $30.
Assuming that the display I have ordered is a direct replacement and my time is free that sounds like a bargain to me plus I get the experience of replacing the display.

As for "disposable" and "not worth the effort and expense", that is one of the biggest problems our society faces these days. I agree that sometimes it makes more sense to replace something than to repair it but we throw out too many things that could (should?) be fixed and that results in the landfills filling up (don't be fooled: a substantial amount of what we sent to e-waste ends up in landfills after the materials that are easy to harvest are removed).
BTW: Instead of buying a succession of newer vehicles every few years I bought that 39 year old motorcycle in my avatar pic as a non-runner and it has been my daily driver for the last 25 years.
 

Sidecar Bob

Dec 19, 2021
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The display and the case arrived on Friday (19 days before Aliexpress said it would arrive). And we have a Heat Warning (= seniors & dogs should stay indoors or go somewhere air conditioned) so I had to find a project to work on indoors. Perfect timing.

The new display looks exactly the same as the original except that is blue instead of green.

Replacing it was easy. The last pin on the left isn't soldered to the board so I gently lifted it while heating the solder on the next one and when that one lifted I moved to the next & so on.
Soldering the new one on was even easier. The biggest issue was that I damaged one of the pads for the LED when removing the old one and didn't notice until the new LED didn't work but an inch of wire fixed that :rolleyes:

When I was putting the first case together I found that the nuts & bolts included for the corners were too long so I had to dig around to find something that would work and in the process I dropped the back of the acrylic case on the cement floor in the garage. Amazingly I found all of the pieces so I glued them back together with ACC and sprayed it with gloss black appliance epoxy.
The extra tester is going to my brother in law so I had planned to put the tester I repaired into the case I repaired so that his will be in original condition.
When the repaired tester's display turned on and I saw that it is light with a dark background that only confirmed my decision.

Original (left, green display) and my "customized" version (right). To my eyes the green display looks sharper in the pic than in person and the blue one looks sharper (picture all the gray as the lighter shade).
2 testers.jpg

BTW if anyone is counting the total cost of the 2 testers was about $43.50 CAD (approx. $33.65 US).
And that's including the money that the seller that sent the one that arrived damaged never did refund.
 
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