Harbor Freight (Cen-Tech) Digital Caliper #93940

I've bought 4 of them, two regular 6" and two of the easy to read 6" and have had trouble with all 4. It seems that when I roll the wheel to close against an object the littlest pressure and the numbers just jump all over the place. Another one won't turn on when the battery cover is in place holding the battery down. It works with the cover off but jumps around like the others when any pressure is applied to the wheel. I might try dismantling as someone else has done and try to fix as they are pretty useless the way they are now. Dick

According to Dick :

First -- check the gib screws on the back side. If they are not tight enough, the head rotates a bit from the pressure of the jaw tip on the object being measured, and this confuses the pickups on the head by changing the angle.

Only after you have tried this should you try the other.

Good Luck, DoN.

I got a cen-tec last Xmas. 11 months it worked fine, then started reading wrong. nothing to clean out of it, but took it apart, still broken. You get what you pay for?

Change the battery?

Mark Rand RTFM

I used 4 batteries in eleven months, tha's not what's wrong with it.

If it's the same as my generic Chinese caliper, it's 24 bits, BCD encoded, IIRC. There's a tiny edge connector under a hatch opposite the battery compartment. It's easy to figure out the pinout by metering from the connector pins to the battery terminals.