98 S40 Blowing fuses

I have a 98 1.9TD S40 which until now has been fine. A week ago while
leaving work I noticed that both the speedo dial and rev counter needles were not working then when I turned on the indicators they also did not work. Upon arriving home I investigated and found that the display panel was completely dead except for the digital readouts. I check the fuses in the drivers footwell and found that 2 fuses had blown F6 and F7. F6 according to the fuse cover was for the instrument panel and F7 just said lights. I changed both fuses and F7 10A blew immediately that the ignition was switched on however F6 20A was ok. I took the car to a local garage who said
that they could not find the cause and that they also could not find
anything that was non functioning due to F7 being left out. Not very helpful but at least my car seemed ok. Now while driving home today the display went again and now F6 has blown again! I have traced the wiring where possible and even spent out money on a Haynes manual even though they do not produce a manual for diesel volvos thinking that at least the wiring should be the same....WRONG.. According to the manual without F7 which is how I had been running I should have no lights, engine management, displays, heated seat etc etc, but in fact I do.

Anyone else had a similar problem or know where I might be able to get hold of a proper wiring diagram. If not then looks like I'm going to be going to an auto electrical specialist and spending a small fortune. I would take it to my local volvo main dealer but at £60p/h labour charges i'm not too keen on that idea. Are there diagnostic machines that can be plugged into the car that would make the fault finding any quicker? Any advice would be very welcome.

Cheers

Tony