https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg4291063/#msg4291063
This clone of T4 is not based on the original ATmega328, but so far on a processor known only to FNIRSI.
The marking on the ATMega328PU-TH case is a fake
Attention! Check with the seller which version of LCR-T4 he will send you, because updating the firmware and upgrading(repair) it is not yet possible! If this is important to you, then this version of the clone has a Chinese APT32F172K8T6 processor installed
Thank you for this information. How did you find out that it has an APT32F172K8T6 microcontroller? I recently bought an LCR-T4 and, unfortunately, I received the "V4.1.3_2022/5/18" hardware version of this tester. I immediately saw something unusual about the microcontroller, and I checked how the (+5V) supply connects to the MCU: GND to pin 18 and VDD to pin 19!
No, this cannot be an Atmel ATmega328P, and the supply pins do match the APT32F172K8T6 pinout! Device marking: it does have an Atmel logo (that looks a bit weird), and "MEGA328P / U-TH / 35473D / 220642H" printed/etched on it. No 8 MHz crystal is mounted, and judging from the empty footprints there is a beginning of a serial-to-USB interface (for a CH340N) on the PCB. (I have seen pictures of this PCB version with the CH340N and USB connector mounted.)
Yes, be careful when ordering a new LCR-T4. If you are expecting to receive a component tester that has a genuine Atmel ATmega328P (which you could then reprogram... ) then a little chat with the seller is recommended. However, resellers may not be aware of this fake clone, or resellers may not be interested in customers demanding a product that has genuine components. My seller stated that the reason for this LCR-T4 having different components (with fake device marking on the MCU) is a "chip upgrade", and no comments on the microcontroller device markings.
So, if you have a chance to see the LCR-T4 before purchasing, it is advised to check the bottom side of the PCB to verify whether there is a crystal present. Also the top side of the "V4.1.3_2022/5/18" version PCB has a distinct pattern of traces running straight from ZIF socket to the 1, 2, & 3 test pads. Many customers have bought this product without knowing or complaining about the MCU. Some customers ask (themselves) what this USB connector is all about, but most customers just report that the device is working fine. I just wanted an LCR-T4 to experiment with and to reprogram it, but I now have to search for an original LCR-T4 clone.