LG 42PX3RV-TA Sound, no pic, YSUS causes shutdown to standby

[BAM]

Hi, been lurking amongst some of the other threads but so far haven't had any luck.

I picked up a couple of non working 42" plasmas, and LG 42PX3RV and Hitachi 42PMA300A, both with the usual sound but no picture. Gave up on the Hitachi as decided not worth the time or money to fix a low res set in my opinion, but would be good if could get the LG up and running.

When I got the LG most of the fuses were missing, from PS, ZSUS and YSUS.
After replacing them none have blown, but if YSUS is connected, the unit powers on for a few seconds with green led, then switches off again to standby red led (power supply protection mode I guess?) If I run without the YSUS fuse it doesn't shutdown and the main board has 2 LED's lit, sound is ok.

The PCBs are dated 2006/01 so guessing not due to the design flaw.

Va, Vs and 5V are ok.

So guess its a YSUS fault right? IPM? Any suggestions where to look next?

I've got the PCBs from Hitachi, but they are 42V6's, not 42V7 like this model. The Hitachi powered on ok, all voltages seemed ok and no fuses blew despite no picture.

Do the 42V6 and V7 use the same IPM on the off chance the Hitachi one is ok?

Also is the missing cables from P803 and P804 on the PS, and P1101 on the main board normal?

Thanks