USA NES with UA6548

[Gabe]

I bought a USA NES with a broken PPU. I replaced the PPU with a UA6538 PAL PPU. Lifted the 18. pin (CLK) and connected to a homebrew 26,6Mhz oscillator. It worked fine in 50Hz. Then i got a UA6548 PAL-M (PAL60) PPU and changed to it. It works in 60Hz with very ugly scanlines, strange colors.
Is there anyone knows what makes this problem?

I have some famiclones with NOAC chip whith 26,6Mhz xtal and jumpers. When i short only one jumper it works in 60Hz with that same ugly scanlines but if i short every jumpers it works fine.

[Charizard700]

That's very interesting.
Does your TV support PAL-M?
And is the master clock 21.477272 MHz or 21.453671 MHz?
Proper PAL-M requires a master clock of 21.453671 MHz.