HP65 display issue

[GreyUser]

Please be aware that if you are attempting to repair the display in a classic, replacing one 5 digit module with a random part will in all likelihood not match the other two with respect to intensity.

Why? Because HP graded the part by intensity and indicated that with a code letter on the back of the device. I've been told that HP allowed for one letter of difference in the three LED packages but personally, I've never seen this, all units I've repaired always had the same intensity code parts.

IIRC this is mentioned in the linked keesvandersanden article.

Your best bet may be to look for a cheap 45 or 80 that can serve as a parts donor and replace all three. Only in that way will you be assured the displays will match in size, intensity and alignment, with the first two being out of your control and the latter being a genuine challenge for the installer.

You will absolutely need professional vacuum through hole desoldering equipment. The boards are too fragile to be attacked with hand pump desoldering tools and solder wick will not get enough of the solder out to free all the pins of a device simultaneously. While you can certainly cut a defective unit out and then remove the pins and clean up with solder wick, that doesn't make sense for otherwise good units that have to come out due to intensity differences.