I loved to work on the old Motorola analogs, they were fun to work on, at least you could repair them board level, the newer ones all you could do is replace mother boards, plug them into a programmer, you were done, no challenge there. Ah PLC5s and slick100s and 500s they were cool, spent many weeks in schools, a couple analog modules, some I/O you could do almost anything, very slow scan times but reliable as hell.