Pickit 3.5 clone repair - Page 1
Forum section: electronics / general

author: yarda
author_rank: Newbie
timestamp: October 15, 2022, 10:23:12 am
content: Hi,I have pickit 3.5 (pickit3 clone) damaged probably by the over-voltage spike on the VDD ICSP pin. There is exploded IC (see the photos). Does anybody know which IC is it (or could read the part number if by chance owns this programmer)? Its name starts with the letter P. I am unable to read more. I guess it's used for the VDD_TAR handling, on the original pickit3 it is handled by the FDC6420C, but the 3.5 clone seems to differs here. I am also going to check the VDD_FBACK whether it fried the AN2 pin of the 24FJ256 or not. The L1 was probably damaged in the factory and seems to work OK. It currently communicates with the USB host and accepts firmware.

author: yarda
author_rank: Newbie
timestamp: October 16, 2022, 01:28:38 am
content: After doing some forensic, I think there is written PLII (more probably) or PLJI (less probably) on the exploded chip. This corresponds with the not very good image I was able to find on the internethttps://www.sunrom.com/media/product/403_1.jpg.Which means TPS2041BDBV switch. I will try to replace it and let's see.

author: DavidAlfa
author_rank: Super Contributor
timestamp: October 16, 2022, 11:28:55 am
content: Lucky you, my ancient Pickit3 clone has the same layoutYeah, it seems to be the part! (Don't connect 24V to VDD pin next time haha)Just in case you screwed something else, I found some nice detailed pictures in a site, attached here.

author: kripton2035
author_rank: Super Contributor
timestamp: October 16, 2022, 11:39:08 am
content: the tps2041 in the sot23 package, has effectively a PLII marking.DBV is the package drawing model...

author: DavidAlfa
author_rank: Super Contributor
timestamp: October 16, 2022, 12:45:11 pm
content: True kripton, as always I was editing the message and also adding more pictures, but people always catch my mistakes faster.I always wondered what was the second SPI flash for (U2, FM25F04), since the official pickit3 only has the AT25SF041 (U4).

author: yarda
author_rank: Newbie
timestamp: October 16, 2022, 01:08:15 pm
content: Thanks.Actually, it was 32 voltsI don't fully understand how it hapened. Hantek PPS2320A power supply resetted itself from 4.5 V / 60 mA to 32 V / 3.1 A upon connection of the pickit. Maybe ground potentials difference or immediate AC drop which caused the reset. I don't trust it any more and use 7805 power "buffer" in between. Let's see whether the MCU in the pickit fully survived. If not, I will also replace it and burn the firmware with another pickitJust hobby project.BTW, the 3 / 3.5 clones seems to share the same PCB layout (I have here one pickit3 clone, unfortunately with the PLII unpopulated), just few components are populated differently and it has different flash, thus it should be possible to upgrade/downgrade respectively.

author: yarda
author_rank: Newbie
timestamp: October 16, 2022, 01:28:27 pm
content: Regarding the second flash, from the seller advertising:" KIT3.5 will never drop the firmware. The firmware is self-recovering, no need to disassemble the shell, no need to flash the program, the firmware is automatically restored in 1 minute."I thought it is just Chinese boast advertising. Maybe it's used as a dual flash? I.e. if the boot from the one flash fails it falls back to the backup flash? I think this is worth deeper exploration.

author: DavidAlfa
author_rank: Super Contributor
timestamp: October 16, 2022, 01:55:50 pm
content: Hantek PSU? No further explanation requiredIf the pickit blew up, I guess the actual MCU also won a 1st class one way ticket on Emirates Airlines to Electronics Heaven!Strangely, there're polyfuses for the data lines but no way of protection for VDD or VPP.However, there's a unpopulated diode for VDD (D1).With a simple mod you could add VDD protection:

author: yarda
author_rank: Newbie
timestamp: October 16, 2022, 08:09:38 pm
content: MCU (12F1572) connected to the ICSP was fried. Host USB port was also friedBut the pickit MCU seems healthy, I flashed logic analyzer firmware to test the output buffers and it seems that everything is OK. It communicates OK through the USB. Unfortunately, there are unprotected feedback pins, like e.g. the VDD sensing circuit. Even with the voltage divider it was far over the absolute max ratings of the chip, thus these pins could be dead.

author: MikeK
author_rank: Super Contributor
timestamp: October 16, 2022, 09:15:54 pm
content: Does the clone use the same MCU and firmware as the official PICkit?

author: yarda
author_rank: Newbie
timestamp: October 16, 2022, 11:28:20 pm
content: Regarding the firmware I don't know, but there was never problem to upgrade/replace the firmware/bootloader by using Microchip tools.

author: yarda
author_rank: Newbie
timestamp: October 16, 2022, 11:37:31 pm
content: Also fixing Lenovo USB port. It seems there is TPS2069DGN fried.