Help on calibrating a Multimeter UT55

[maujavier91]

Hello, i have a Uni-T UT55 and is currently giving wrong readings i think the calibration is completely off, as it measures negative voltages in the VDC scale having the test leads in the air, this also occurs in VAC, measuring -230Vac in the air, or measuring negative frequency, no reading is correct, also measuring the resistance touching both test leads gives negative reading in some scales, is this a calibration error or could some part of the circuit be damaged, if it is a calibration error, how could i return it to normal readings. I attach the schematic i found online.

[mjhvanvliet]

Have you tried to change the battery? I think the calibration is not your problem, but an empty battery or broken meter.

The IC used is ICL7106: https://www.intersil.com/content/dam/Intersil/documents/icl7/icl7106-07-07s.pdf