So i removed the mechanism and replaced tape audio with AUX lines with no result (via
pins (L3, R3) of the volume controller IC151) so I figured out that the system controller
(IC501) is testing for some conditions to send tape audio for processing :
the tape must be loaded and the supply/takeup reel must be spinning, because empty tape
(with no magnetic tape inside) gets ejected. The solution is to insert a blank tape to listen to
AUX input.
The problem is that the tape mechanism is taking up space needed for a power supply
module and it has to go away.
So I measured the voltages at the mehanism connector (CN352) when tuner is on (tape
off) and when the tape is playing: (H = 4.7v, L = 0v)
Pin Description Tuner Mode Tape Mode
---- ---------------- ------------ ------------
1 * C-MOTOR L Vcc <<<
2 GND L L
3 LM+ L L
4 LM- L L
5 * POS2 H L <<<
6 * POS1 L H <<<
7 POS3 H H
8 GND L L
9 * POS4 L H <<<
10 AUTO. MTL L L
11 * REEL1 H [L ~ 3.3v] <<<
(Alternating)
12 REEL2 (N/C)
13 * B+ (8.5V) L B+ <<<
So I concluded that pins (1, 5, 6, 9) must be set accordingly, and I guess that pin 11 is the
reel rotary encoder stroboscopic signal or something, and I have no idea how to simmulate
that. If someone can help me bypass the mechanism and make the system controller
believe a tape is there and playing, that woud be great.
Thank you very much for any help or suggestion.
pins (L3, R3) of the volume controller IC151) so I figured out that the system controller
(IC501) is testing for some conditions to send tape audio for processing :
the tape must be loaded and the supply/takeup reel must be spinning, because empty tape
(with no magnetic tape inside) gets ejected. The solution is to insert a blank tape to listen to
AUX input.
The problem is that the tape mechanism is taking up space needed for a power supply
module and it has to go away.
So I measured the voltages at the mehanism connector (CN352) when tuner is on (tape
off) and when the tape is playing: (H = 4.7v, L = 0v)
Pin Description Tuner Mode Tape Mode
---- ---------------- ------------ ------------
1 * C-MOTOR L Vcc <<<
2 GND L L
3 LM+ L L
4 LM- L L
5 * POS2 H L <<<
6 * POS1 L H <<<
7 POS3 H H
8 GND L L
9 * POS4 L H <<<
10 AUTO. MTL L L
11 * REEL1 H [L ~ 3.3v] <<<
(Alternating)
12 REEL2 (N/C)
13 * B+ (8.5V) L B+ <<<
So I concluded that pins (1, 5, 6, 9) must be set accordingly, and I guess that pin 11 is the
reel rotary encoder stroboscopic signal or something, and I have no idea how to simmulate
that. If someone can help me bypass the mechanism and make the system controller
believe a tape is there and playing, that woud be great.
Thank you very much for any help or suggestion.