Two Digit LED Display Not Illuminating Completely

Theory why the two segments blew (if in fact are blown)?

Method to test and correct possible circuit deficiency?

These little gizmos are a pain the keester to replace. Ha.

I should take a comparative picture of the undersides and post too for fun. Unmarked as to pinout (datasheet is clear though in this regard). Old one is plain Jane. New one is interesting to look at.
 
Well you obviously have rework equipment, it'd be a lot harder without :D
Just light a few segments on the old display using the datasheet to ensure they're the same pinout. High probability they are - if you got at least one segment to light.

The schematic is of poor quality and can't really give much guidance from that angle, was a stretch to read anything from it...
 
Poked around some. You know. Measured a few of the resistors on the LED PCB. Seem good. Measured some of the voltages where the LED chip seats. Readings are uniform. Doesn't seem worth doing much more than that. Will plug in new part when it arrives. See what happens.
 
I LIKE the green displays. Reminds me of my trusty old euro Galaxy 2100, affectionately known as the Green Weenie.

Maybe a bit late to the party, but it's more common for the printed copper traces in the flat wire harness on the channel selector board to delaminate and/or crack. First thing I'd look at anyway. Take a VOM to it and check continuity on that.
 
sKiZo said:
flat wire harness
Click to expand...
welcome to the party!

yah. gave that a quick look earlier. continuity was gouda. will look again more closely.

am reminded -- that I really need to follow my protocols; thorougly range around; give the whole enchilada a closer visual inspection; use magnification.

thanks for opinion on display color and mention of your Galaxy. caused me to look that model up. noticed the fine tuning control. have been looking at the Galaxy make and models. great fun! thanks again.
 
I said might take a picture comparing undersides old and new (kind of interesting). Here that is, with pinout.

Cobra 25 LED 6.jpg
 
The new part worked. All LED segments now illuminating. Old LED display chip had two blown segments

This unit uses a Common Anode display. To recapitulate, information 'out there' is wrong that all models before 2014 have Common Cathode displays. This machine was manufactured in 1989.

https://www.digikey.com/product-detail/en/kingbright/DA04-11EWA/754-1662-5-ND/3084350

My sincere thanks to you all for your help on this project.

Here's a picture with the new display.

Cobra 25 LED 7.jpg
 
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Red? Green? Red Green? What's the difference, as long as the wimmin find ya handy?

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Then again, I still got the scars from the last woman who found me TOO handy ...
 
Just tell people its a 25XLR with a new faceplate. Not sure they ever made a 25 XLR, but there was a 29 XLR and a 29 LTD Classic. The only obvious difference was red vs green displays.
 
Those exist and they look awful IMO. I went through a blue interior lighting phase in my late 20s. I changed it back to stock when I realized how much it actually hurt my eyes. Its mildly updated though, I used warm white LEDs with the stock lens filters to give me the stock pale green color but somewhat brighter.
 
You can see hanging down below on this homemade mount in my car is a Uniden 505XL which I've been runing the past few weeks.

I might switch it out for the Cobra 25 for a while and see how the old unit plays.

Interesting to hear the CB radio traffic. Every once in a while there is something useful said. I've had some success asking for help on traffic conditions.

The other radio is a 20-year-old Yaesu 2600 (2-meter rig) I picked up cheap from a guy in Cleveland not long ago. Supposedly has not seen much use.

Don't much like these backlit LCD displays.

The mount is made from a piece of 'bar aluminum' and goes down to a seat bolt.

Panavise.jpg
 
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