This affects all V5 main boards, older Pi4 and recent Pi5 ones.
I’m adding this to the wiki tutorial, so users with related issues could try this fix.
To resume, and as @simmeah as already explained, the FPC connectors doesn’t fit perfectly the standard ribbon cables we include in the V5 kit, causing the cable to bent when closing the tonge and potentially causing bad contact or, at worst case, damaging the flat cable.
The reason is we accidentally choose a wrong part number and didn’t realize until now because the difference is really small it works most of times. Indeed i never suffered the issue in any build i did here, in zynthian labs. And i did a few ones!
We have already fixed the BOMs so next boards will be manufactured with the right part number. Also, we are fixing all boards we have stocked so:
ALL V5 KITS SOLD AFTER 2025-06-01 ARE FREE FROM THIS DEFECT and you don’t need to fix this because we already did. If you have issues, the cause is not this.
Anyway i would like to offer a solution for those having issues with this. Indeed, the solution is simple and it has been already explained by @simmeah:
Use a cutter or scalpel to cut the 2 tiny plastic bumps that cause the issue.
The bumps are really tiny and you probably need good eyes or magnifying glasses. The tool must be well sharpened, so the plastic bumps can be cut will minimal force. Be extremely careful to not worsen things by breaking the FPC’s tonge.
You must repeat the operation for all FPC connectors used by V5. They are:
Main Board
- CONTROL-1
- USB-C1
- SDCARD-RBPi1
Control Board
- CONTROL-1
I only recommend to perform this action if you have any of these problems:
-
Control board connection issues, like:
- Control board not being detected on first boot.
- Some buttons or knobs behave erratically or doesn’t work.
-
SD-card extender doesn’t work or it’s not stable enough. You should be sure of using good quality SD-cards of the right sizes (32 or 64GB). Also, check the SD-card extender is not broken nor damaged.
and YOU HAVE DOUBLE CHECKED the build tutorial and you are sure you followed the instructions carefully and everything is according to them. This should be a last-resource action before considering to replace the board.
ALL V5 KITS SOLD AFTER 2025-06-01 ARE FREE FROM THIS DEFECT, so you don’t need to fix it because we already did. If you have issues, the cause is not this.
May the force be with you 