radcomtech
Member
- Joined
- Aug 11, 2017
- Messages
- 8
I posted in another thread and I have four updates since 2017.
I originally built a number of adapting regulators to allow generic common power supplies to function
as the original TASCAM PS-M1 did.
The only difficulty is in finding the vintage original 4 pin trapezoid power connector.
I found a workaround in the use of older MOLEX female pins like the kind used inside PC Computers
in the 1990s; the four pin internal Hard Disk Power couplings which are still on modern internal
Desktop and Tower ACDC Power Supplies. They are about 10thou too big but a small section of
soft small solder wire will tighten them to use as connections to the TASCAM power Jack port
without hacking up the TASCAM in sacrilege!
Recall that the PS-M1 supplies +10Volt, -10Volt and "7VoltDC". The last rail is *not correctly labelled* from TEAC: That connection is actually a very low 7VAC supply that sends timing of 100 Hertz (Europe) to 120 Hertz(N.America) into various TASCAM equipment. The 644 required this timing from "mains" power to bring up the midicenter, group levels, and tape transport including the cool 'jog' thing.
It also allowed the Cassette to record/play twice as fast at 3-3/4 (3.75 IPS) with DBX.
I discovered that:
(1) The original PS-M1 power bricks were designed for a number of different models.
(2) MM1 mixers do not need that 100-120Hz timing signal marked 7VDC(incorrecly)
(3) 644 MidiCenter with 4 track Direct drive Cassette Tape draws quite a bit more juice off the +10Volt rail. Almost 1Amp at FFw or REV
(4) the -10V rail needs to be very stable with noise filtration constants to attenuate well above 66KHz to avoid contamination of all channel reproduction.
Therefore, the design of my adapter changed.
I would try to find a Power brick old school style that has +5, +12V(1amp) and -12V (at least 300mA).
I would ignore the +5Volt rail and run only one LED indicator and drop resistor from that line.
I would employ two linear regulators LM317 and LM337(negative version) with potentiometers to exactly vary the outputs to 10.0V and -10.0 Volts. And this worked 100%.
Then , I take the 10V rail output, and power the Astable Oscillator set for 120Hertz and produce a 10Vpp signal. This also worked.
I discovered the TASCAM equipment power pins inside the port are 1.5mm slightly smaller than the 1.85mm female molex pins with the workaround mentioned above.
I found a surplus "brick" style ACDC with "triple play" output; these bricks were commonplace for Backup Tape drives in the 1995 era like Colorado Tape 8mm and so on. Bonus; almost all have DIN5! plugs, so I used DIN5 right angle on my adapter board. This also worked well.
Finally, the last client with 644 has 3D Printer capability and at some point He may be able to model the 9x11mm trapezoid pattern to embed four Molex female KK series pins into a PS-M1 "plug".
I think I may go ahead and create another run of boards in February 2021 because I had received at least 5 or so inquires on missing or lost PS-M1 adapters.
I am also looking into the voltage adaption of the Chinese single input switcher (common) module, to modify it to supply +10 and -10 by change of just two resistors; in theory, for now. Then I would add a 7555 astable oscillator circuit to generate the 120Hertz frequency square wave to drive the more intelligent boards.
I will be attaching images from this new build that I have recently completed, using perf board.
I will contact all the back-email requests and letting them know my Kit price and timetables.
I find the TASCAM equipment fascinating and I have been at Electronics Repair since 1976 (student) and certified since 1979.
The attached image ; on the left is the +10V adjustable regulator, and the -10 is on the right. In the middle is the 555 Oscillator , and the DIN5 input connector is on that side of the perf board.
I originally built a number of adapting regulators to allow generic common power supplies to function
as the original TASCAM PS-M1 did.
The only difficulty is in finding the vintage original 4 pin trapezoid power connector.
I found a workaround in the use of older MOLEX female pins like the kind used inside PC Computers
in the 1990s; the four pin internal Hard Disk Power couplings which are still on modern internal
Desktop and Tower ACDC Power Supplies. They are about 10thou too big but a small section of
soft small solder wire will tighten them to use as connections to the TASCAM power Jack port
without hacking up the TASCAM in sacrilege!
Recall that the PS-M1 supplies +10Volt, -10Volt and "7VoltDC". The last rail is *not correctly labelled* from TEAC: That connection is actually a very low 7VAC supply that sends timing of 100 Hertz (Europe) to 120 Hertz(N.America) into various TASCAM equipment. The 644 required this timing from "mains" power to bring up the midicenter, group levels, and tape transport including the cool 'jog' thing.
It also allowed the Cassette to record/play twice as fast at 3-3/4 (3.75 IPS) with DBX.
I discovered that:
(1) The original PS-M1 power bricks were designed for a number of different models.
(2) MM1 mixers do not need that 100-120Hz timing signal marked 7VDC(incorrecly)
(3) 644 MidiCenter with 4 track Direct drive Cassette Tape draws quite a bit more juice off the +10Volt rail. Almost 1Amp at FFw or REV
(4) the -10V rail needs to be very stable with noise filtration constants to attenuate well above 66KHz to avoid contamination of all channel reproduction.
Therefore, the design of my adapter changed.
I would try to find a Power brick old school style that has +5, +12V(1amp) and -12V (at least 300mA).
I would ignore the +5Volt rail and run only one LED indicator and drop resistor from that line.
I would employ two linear regulators LM317 and LM337(negative version) with potentiometers to exactly vary the outputs to 10.0V and -10.0 Volts. And this worked 100%.
Then , I take the 10V rail output, and power the Astable Oscillator set for 120Hertz and produce a 10Vpp signal. This also worked.
I discovered the TASCAM equipment power pins inside the port are 1.5mm slightly smaller than the 1.85mm female molex pins with the workaround mentioned above.
I found a surplus "brick" style ACDC with "triple play" output; these bricks were commonplace for Backup Tape drives in the 1995 era like Colorado Tape 8mm and so on. Bonus; almost all have DIN5! plugs, so I used DIN5 right angle on my adapter board. This also worked well.
Finally, the last client with 644 has 3D Printer capability and at some point He may be able to model the 9x11mm trapezoid pattern to embed four Molex female KK series pins into a PS-M1 "plug".
I think I may go ahead and create another run of boards in February 2021 because I had received at least 5 or so inquires on missing or lost PS-M1 adapters.
I am also looking into the voltage adaption of the Chinese single input switcher (common) module, to modify it to supply +10 and -10 by change of just two resistors; in theory, for now. Then I would add a 7555 astable oscillator circuit to generate the 120Hertz frequency square wave to drive the more intelligent boards.
I will be attaching images from this new build that I have recently completed, using perf board.
I will contact all the back-email requests and letting them know my Kit price and timetables.
I find the TASCAM equipment fascinating and I have been at Electronics Repair since 1976 (student) and certified since 1979.
The attached image ; on the left is the +10V adjustable regulator, and the -10 is on the right. In the middle is the 555 Oscillator , and the DIN5 input connector is on that side of the perf board.
