Lenschanger have no real effect on anything earlier than V5 other than erasing the reference values sony programmed to the eeprom in the factory.
If you try to program a V4 t use a HD7 laser it will have no effect. This is what I mean. The PS2 might work with the HD7 but will first try to use it as if it was a 400x laser ....
SCPH-10000_GH-001 SCPH-15000_GH-003 SCPH-18000_GH-008 SCPH-30001_GH-005 SCPH-30000_GH-016(V4) SCPH-30001_GH-010(V4)
2xSCPH-10190, 2xSCPH-10350, 2xSCPH-10280
"**** j0 hackers!"
-Sjeep (As seen on TOXIC OS ELF...)