Author Topic: Need help finding 7 segment display replacement  (Read 196 times)

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Offline Bari

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Need help finding 7 segment display replacement
« on: May 02, 2020, 06:08:05 pm »
Over time several segments have gone out on the 4-digit 7-segment display for my smoker.  The manufacturer no longer makes replacement modules (it's only 4 years old!) .  I only found one third party seller that has a few in stock that wants nearly what it would cost for a new smoker!  After some effort separating glued parts, I was able to get the board out and took the provided pictures.  Despite my best effort I can't find this specific part online.  I have found similar parts (links below), but am not sure about the pin compatibility.  If anyone has insight given the pictures below it would be greatly appreciated.  Thank you in advance.

Candidate part 1:  https://www.digikey.com/product-detail/en/sparkfun-electronics/COM-09481/COM-09481-ND/7319633
Candidate part 2:  https://www.mouser.com/ProductDetail/Lumex/LDQ-M3604RI?qs=%2Fha2pyFaduiH94%2FpqkGkOmZ9JuBdxV29lDG0U%252BAKgvwdRPJUBZDSbw%3D%3D
(I am still looking for alternatives since both of the above are not in stock  |O )
 

Offline WattsThat

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Re: Need help finding 7 segment display replacement
« Reply #1 on: May 02, 2020, 07:00:03 pm »
It’s a multiplexed display so if the same segment(s) are missing in all four digits, it’s not a bad display. If that’s the case, it’s a segment driver/resistor issue and I’d be looking at those 300 ohm resistors, the soldering on R3 and maybe R4 appears dodgy.

If you need a new display, you have to figure out if it is common anode or common cathode. The Sparkfun display is definitely a no go since it has 16 pins, the original 12. The Lumex might be a match but it’s non-stock so that’s a bust.

Better figure out the actually need before you go looking for a replacement. You can test the display with a DMM on the diode range. The four display pins without 300 ohm resistors are the four individual digit connections, the eight leads with resistors are the segments.

PS: The display looks identical to the units used on those $5 eBay digital clock kits.
 


Offline Bari

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Re: Need help finding 7 segment display replacement
« Reply #3 on: May 02, 2020, 09:19:27 pm »
The segments that are not working are not the same in all four digits.  For example, one digit has the center horizontal segment out, and the adjacent digit has the lower left vertical and the lower horizontal segment out.  Good news I suppose since if it is the display, at least I may be able to replace it.  Note that only 12 pins of the 16 pins pass through the board (two rows of 6 pins pass through).  The outer 4 pins appear to be an aid for assembly since they do not pass through the board and are not connected to anything.  I tried to show this with arrows in one of the photos, but there are 16 pins, with only 12 used.

I agree the original solder connections looked poor, so after I took the pictures I re-soldered them, and nothing changed.

Thanks for the tip, I will look at the digital clock kits.
« Last Edit: May 02, 2020, 09:25:24 pm by Bari »
 

Offline kripton2035

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Re: Need help finding 7 segment display replacement
« Reply #4 on: May 02, 2020, 09:42:12 pm »
I would desoldier the display, and then reverse engeneer the wiring of it.
it's not difficult. then you would be sure of the wiring and order the right replacement.


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