GDSammet wrote:

Here is a close up image of one of the segments with 1.7v power  applied.  I used a 105mm macro lens with a 36mm extension tube.  The "silicone chip" is less than .5mm in diameter.

Yes, this is indeed the LED type I was referring to. Although it was still smaller in the early calculators, and the displays actually had a plastic "magnifying lens" over each digit to make them readable. I think I have one in my junk box somewhere... as well as some larger early LED 7-segment displays, which internally had LEDs pretty much like in your picture and a "light box" above to diffuse the light.

Well done with the picture BTW 🙂

 

Derek

auric wrote:

Gerhard:

I successfully redid the entire display on my BM 8000 2 weeks ago replacing all segments with surface mount LEDs.

You really need to replace all of them because there the voltage between the old and new leds don't match and more importantly because the display is strobed. The new ones are much more efficient and are too bright.

I replaced all the current dropping resistors with 820 R in order to match the brightness of the original display. I prefered mine to be a bit brighter than original, but if you are picky you can go with a slightly higher value dim it a bit.

As you dim the LED the color gets closer to the original, but it isn't exactly the same.

I've taken pictures of the entire process which I'd like to share with the group but haven't figured out how to attach them.

Regards,

 

Derek

I am curious which LEDs you replaced, for which display, and what value.  I have ordered several which might work, but I have not received them yet.  Which resistors did you replace?  My volume display and balance displays are completely dead.  Only one or two segments work.  The tuning display has 3-4 segments which are dead or dying.  In looking at the Service Manual diagram, the volume and balance "share" resistors which might be good in my case, however, the tuning display might have to be completely rebuilt also since all of the segments are related to the same set of resistors.

I just finished replacing the R226 Trim Pots on the Amplifier boards.  I found 100ohm Trim Pots with the same footprint as the stock ones.  I used Digi-Key (DigiKey.com) part number 3352E-101LF-ND ($1.24 USD each).  The legs fit perfectly in the factory holes without bending them or making any modifications.  Once I replaced them and reset the milivolts to 18mv everything worked perfectly.  It was easy to get exactly 18mv also, since the new Trim Pots were clean.

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