V7 Problem , some sound gone , loads as PSX

I have an install problem on a V7 SCPH39002 PAL console .

The problem is that ther is no longer any sound on the boot splash screen , and PS2 DVD-R loads with the PSX logo .

The chip installed was a M2 v1.30 , and this is probably my 1000 install to date . There are absolutely no bridges or splash that I can see , and even with the chip removed , the same problem is occuring .

I've repaired a lot of PS2's but this one has me totally stumped , any idea's anyone.

sounds to me like the dreaded tiny tiny tiny peice of solder ball syndrome that went not noticed during install and has lodged itself somewhere main check the resistors above the emotion engine lightly brush the board down and i mean lightly to see if you disturb the lodge if not get them milk bottom bottles out and start searching.
EnTiTy