Hi From Brazil!
I just recently bought a 644 Midistudio Tascam. It is mostily working, but for 2 problems:
1 - Channel 3 is working, but is not sending level information for the display - none of the inputs is showing level: mic, line level or tape playback. But is is sending signal for the tape recording head and all of the outputs. I swapped the channel 3 board with channel 1 board and now the channel 1 input on the display is not showing signal . So the problem is contained in the channel 3 board itself. Analysing the schematics I understood that the IC TC9164N is resposable for the eletronic switching and for sending the level signal to be interpreted by the display circuit. So my guess is something wrong with this IC or some component down the signal path.
2 - Channel 3 on the tape head is not sending a aceptable output on tape playback - the signal lacks high frequency information (only bass and mids are present). I swapped the channe 3 input cable coming from the tape head with channel 4 on the rec/play board and the behaviour is the same: the cable with the channel 4 signal inserted on the channel 3 input is giving an OK signal level and channel 3 inserted on the channel 4 have the same bad signal than before, lacking highs. So the channel 3 on the Rec/play board is OK and something is happening in the tape head, on channel 3 only.
I did some researches and some sugested to demagnetize the tape head (I still do not have a demagnetizer...)
Tape head are not worn and the almost invisible tape head gap seems to be the same width on all channels.
Any Sugestions for these 2 problems?
Thank you very much guys for the attention!!
I just recently bought a 644 Midistudio Tascam. It is mostily working, but for 2 problems:
1 - Channel 3 is working, but is not sending level information for the display - none of the inputs is showing level: mic, line level or tape playback. But is is sending signal for the tape recording head and all of the outputs. I swapped the channel 3 board with channel 1 board and now the channel 1 input on the display is not showing signal . So the problem is contained in the channel 3 board itself. Analysing the schematics I understood that the IC TC9164N is resposable for the eletronic switching and for sending the level signal to be interpreted by the display circuit. So my guess is something wrong with this IC or some component down the signal path.
2 - Channel 3 on the tape head is not sending a aceptable output on tape playback - the signal lacks high frequency information (only bass and mids are present). I swapped the channe 3 input cable coming from the tape head with channel 4 on the rec/play board and the behaviour is the same: the cable with the channel 4 signal inserted on the channel 3 input is giving an OK signal level and channel 3 inserted on the channel 4 have the same bad signal than before, lacking highs. So the channel 3 on the Rec/play board is OK and something is happening in the tape head, on channel 3 only.
I did some researches and some sugested to demagnetize the tape head (I still do not have a demagnetizer...)
Tape head are not worn and the almost invisible tape head gap seems to be the same width on all channels.
Any Sugestions for these 2 problems?
Thank you very much guys for the attention!!
