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WA4NVE
02-26-2009, 10:08 PM
Anyone have experience with a Sencore LC75 (Z meter 2 ) Capacitor-Inductor analyzer? Cannot get it to zero out. Otherwise is reads the capacitance correctly - if you substract what is shown on the display before attaching the test leads or capacitor. Any thoughts appreciated -
would also like to locate a service manual and schematic.

Thanks
Phil
WA4NVE

AC0OB
03-01-2009, 04:08 AM
Generally speaking, one separates the leads for Cap cal. and connects the leads for L cal. for each range since you want to account for lead inductance or capacitance.

L and C are measured using an oscillator with the L and C as part of the oscillator circuits, and the osc. pulses are counted.

In the later LC instruments, a PIC chip does the measuring with an internal A/D converter and using a program burned into the PIC.

You could have a component in the oscillator circuit that has changed value, or potentially a voltage regulator going bad.

Without seeing the schematic, it would difficult to help you further.

W5DWH
03-01-2009, 04:14 AM
You need to short the leads together and press the switch toward "short" then separate the leads and press the switch towards 'lead open".

You have to do this everytime that you measure a small cap (in the pf or smaller range) or the test lead's capacitance will make your reading be too high.

73 de W5DWH

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