Willem stop working

[law81]

Hello,

i have a Willem eprom programmer PCB50B and until today everything worked fine, multiple 27c4001, 27c2001, 27c020, 27c256B and 27c322 (with 16 bit adapter) were programmed correctly.
Today with no changes in the configuration, jumpers, O.S. and so on, it has begun to fail with all chips that i tried, 6 chips 27c4001 and 6 chips 27c256b.
If i try to burn 27c4001 i get this error "Error at 0x000000 Chip = 0xFF buffer = 0xF3" and similar with 27c256b "Error at 0x000000 Chip = 0xFF buffer = 0x31".

If i run blank test it works perfect saying device is empty and if i read the chip, it completed at 100%. I use a power adapter 12v 1.5A output.

Any idea?

Thanks in advance.