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Insulation Tester HP-6688B

An insulation tester for under 50 CHF. Let's see if it's any good.

Wow, you really get a lot for your money. It's quite large. Click: Full size
Display with backlight turned on. Click: Full size
Connection sockets. For insulation measurement, I will only need E and L. Click: Full size
Back side. Click: Full size
Battery compartment. It requires 6 AA batteries. Click: Full size
Datasheet measurement ranges. Click: Full size
Datasheet types. Click: Full size
Advertisement: size. Click: Full size
View inside. Click: Full size
Transformer for high voltage generation: yellow. Click: Full size
Voltage multiplier on the left with blue capacitors. Click: Full size
Wires to the 4mm sockets. Click: Full size
MELF resistors. Click: Full size
1.2 MOhm resistor.

Presumably for operator protection. At 5000V, a maximum of about 4 mA flows through it, which is not lethal. 		Click: Full size
R61 27 kOhm. Click: Full size
I am trying to reconstruct part of the circuit. Schematic.


Click: Full size
I still have some resistors lying around and will measure them.

Test resistor 10 MOhm. 		Click: Full size
Test resistor 100 MOhm. Click: Full size
Test resistor 1 GOhm. Click: Full size
Test resistor 10 GOhm. Click: Full size
Test resistor 100 GOhm. Click: Full size
Measurement results.

The measured values match the nominal values surprisingly well. The voltage measured with a Tektronix TX3 also fits well.
The resistors are not precision resistors and I have not measured them independently.
With this voltmeter, I can only measure up to 1000V. Due to voltage ratings, I cannot measure all resistors in all voltage ranges.


Click: Full size
For this price range: I am impressed.