What's new
What's new

Anyone ever replaced/repaired the LCD screen on a Mitutoyo SJ-500 surftest?


Cast Iron
Jan 16, 2016
I have an older (90s) SJ-500 surftest/profilometer and the screen suddenly died on it. When examining it closely I realized that the backlight for the LCD is dead because if I shine a bright light on the screen, I can still see everything. The touchscreen functionality still works and everything.

However, Mitutoyo does not sell the LCD for this unit anymore (it's part # 12AAK763). I do not have $13500 for a new unit, especially when this one still works just fine minus the screen backlight. I'm pondering if it's possible to replace it with a similar screen - has anyone done anything like this? I'd hate to have to sell this thing off for parts.


Feb 21, 2022
I'm assuming you are talking about the LCD display on the large printer unit? It should be replaceable, although the (I assume) resistive touch screen layer may complicate things as most touch screens are capacitive these days. Opening it up, pulling the display manufacturer and part number is going to be the start. You can learn the dimensions and specifications of what you are looking for. It will likely have been an off the shelf display at the time, if you are lucky the touch interface layer is actually separate.

There are also some instructionals on cold cathode backlight replacement, some are focused on using LED's which are longer life. How comfortable are you with tearing into the old gal? Also, those cold cathodes typically run at higher voltages, so just make sure you know where to avoid.

I think a professional electrical repair who focuses on retro stuff could help at a manageable cost, CCBL failure is a common enough issue with older hard to replace displays.

The other thing is that I think the instrument itself can be driven from a computer, so that stand alone printer and driver unit may not be required to continue using the guts of the system. Obviously there will be costs for the software and interface, but worth investigating.