So I had one of these (a T7) but it just broke and now thinks everything's a zener diode. Any idea where one can get a "good" one - I love the feature set and speed - it was a great tool but yeah I'm annoyed now. Would appreciate any advice.
Try this: Connect DC voltmeter to “A” and “K” zener test ports. Minus to “A,” plus to “K.” Then press LCR-T7 “START” button and observe voltmeter. It should read >25V. If <24V then there is a fault in the DC-DC converter circuit which steps up from the battery voltage to the expected 25-30V zener test voltage.
I believe the software checks this “A” to “K” voltage
first. If >25V then it concludes
“no zener is connected” and moves on to performing the standard transistor tester tests at ports 1,2,3. But if open-circuit voltage from “A” to “K” is <24V then it
stays in zener test mode and
won’t do anything else.Also please test several zener diodes, for example 5V, 12V, 15V zeners. Are the results within +/- 1V of the zener’s rated voltage? Also while testing a zener diode: Does the zener get hot after few seconds? (It shouldn’t). If zener gets hot there is definitely a fault in the zener test hardware circuit.
I have three different LCR-x transistor testers with totally different internal circuit designs. Starting in 2022 some Chinese manufacturers substituted <$1 USD MCU chips for the traditional Atmel ATmega328, -324, or -644 MCU ( >$5 USD each and rising ). One of my LCR units with non-Atmel MCU developed the
“zener gets hot” fault but otherwise still works OK otherwise.
My units have the following open-circuit voltages from K to A:
LCR-TC2 with Atmel ATmega324 MCU: 25.4V
LCR-TC1 APT32F172K8T6 MCU: 30.2V
LCR-TC2 LGT8F328P MCU: 25.2V
Note: The Chinese manufacturers interchangeably label their models as LCR-T7, LCR-TC1, or LCR-TC2.The only way to identify
“what is inside the plastic box” is from a photo of the PC board. However the vendors don’t provide photos of the PC boards.