Hello Paul and thanks for your help.
I've been trying to figure out what the issue is these past few days but now i am realy stuck.
I've put a 74HCT04 after the 12th chip and the 28th chip. By testing them, i found out i had a low level (around 2,5V) on the output of the 2nd buffer chip, on my LATCH wire. This was due to a very tiny short circuit between LATCH and GND around my 36th chip.
After fixing this issue, this is the behaviour i have :
- from chip 1 to 12, everything works fine
- from chip 13 to 28 (betwenn the two 74HCT04) the signal is one pin ahead : if i try to power pin 7 from chip 12, it will power it AND pin 0 from chip 13. When i try to power pin 0 from chip 13, it will power chip 1, etc.
- from chip 29 to 32, the signal is 1 AND 2 pins ahead. If i try to power pin 0, it will power pins 1 and 2.
- from chip 33, it doesn't respond and stays on (but weak because of too much power consumption) all the time.
I made many tests but can't figure what is wrong. The buffer chips seem to put an offset so i will try to run the DATA wire thru the buffer too, so if there is a delay it will be the same. My soldering might also be at fault!
Do you have any other suggestion?