Hello Norbert
I am confused by your post. 8340238 is the B&O part number for IC3 on the CPU board, namely a 6500/1 MASTER. IC4 on the CPU board is a 6500/1 SLAVE and has B&O part number 8340239.
What are the symptoms of the problem? I have had two BM8000 with faults with the tuning not working (confusingly not working in different ways) and both faults turned out to be the same component in this same area of the CPU board.
Richard
Some of my B&O: BV3/32, MX7000, MX5500, LX5500, MX4000, BM8000, BM6000, Overture, BL8000, BM6000 Quad, BM4400, BM3400, BG-CDX, BM3000, BM1001, BM1200, BM1600, BM1700, BM1500, BM1400, BM2400, BM2300, BM4500, BM4000, BVM70, BVS45-2, BVS60, BC7700, BM2200, BM1900, BG8002, BM1202, BVPenta, BVP45