Answer to:
Doesn't power on ? We have on older TC1210 seen some tantalum capasitors turning into perfect shortcircuits.
Please try to remove the two 'bucket' sub-PCBs and see if the TC1210 will power up.
These tantalum capacitors are: C40, C42 and C44 (three on each sub-PCB)..
Please replace these 10uF/16V with 10uF/35V tantalum capacitors (TC order code 210 2100 42).
Answer to: Noise in one channel ?
A TC1210 being noisy in one channel is probably due to a faulty 'bucket' sub-PCB. Please try to swap the two boards.
A noisy 'bucket'-PCB is not repairable and should be replaced (TC order code 704012811).
Answer to: PPM hanging ?
A hanging or stuck input meter is most likely caused by a bad or temperature sensitive LM339 (TC order code 420011011)
IC304, IC305 (channel 1) or IC704, IC705 (channel 2).