Tascam 688 channel grouping/record issue

Discussion in 'TASCAM DIY Repairs and Mods' started by davecunningham, Feb 9, 2023.

  1. davecunningham

    davecunningham New Member

    Feb 2023
    Hi! First post here.

    I've got a 688 in with an odd issue. Everything functions as per normal, except for the tape groups. I've done a record test and it has shown the inputs all to be working, the signal is reaching the mixer, however GRP 8 is very quiet regardless of what channel is sent when monitoring in.

    Here's where it gets weird - signal sent to GRP 5 actually record to GRP 6. GRP 6 is recording to GRP 7, GRP 7 is recording to GRP 8, and GRP 8 is recording to, the void? While GRP 5 stays silent.

    The machine seems to be extra noisy too - really headache inducing white noise through the headphones, almost level with the output.

    Wondering if anyone on here has tackled a similar situation, and could point me in the right direction. I am thinking that potentially if someone else has been inside before they may have mixed up a molex connector? Or maybe a problem with the 4066 cmos that many others seem to be having problems with.

    thank you