Schematic and power-supply requirement for Tascam MM-1

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Andy Peters

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A friend bought a Tascam MM-1 line mixer which did not come with a power supply. The manual for the mixer and the silkscreen on the back panel call out a +/- 10 V supply at an amp.

Does anyone have a schematic for this guy?

The mixer has a sorta odd square 4-pin DIN-type connector. We don't know the pinout of the connector.  He's willing to replace the connector with something that fits in the hole and otherwise mates with whatever power supply he gets.

Also, I don't know if the mixer has further regulation on board.  If there are regulators in the thing, seems to me that using an easier-to-find +/- 12 V DC supply would be the simplest solution, assuming the regulators can handle the extra drop.

I would take the thing apart and figure out how it works, but he's in Chicago and I'm in the desert.

thanks, gang.

-a
 

Gene Pink

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Andy Peters said:
A friend bought a Tascam MM-1 line mixer which did not come with a power supply. The manual for the mixer and the silkscreen on the back panel call out a +/- 10 V supply at an amp.
According to an online PDF of the MM-1 owners manual, it uses a Tascam PS-M1 supply, which is also  used with other Tascam products.

There is more to it than +/- 10V, there is also a +7V @ 10mA (???). This jpeg may help.

Gene
 

Andy Peters

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Gene Pink said:
According to an online PDF of the MM-1 owners manual, it uses a Tascam PS-M1 supply, which is also  used with other Tascam products.

There is more to it than +/- 10V, there is also a +7V @ 10mA (???). This jpeg may help.

Gene

That explains the four-pin connector, though the manual for the mixer doesn't mention the +7 V requirement. That makes things trickier.

It would still be nice to know whether the ±10 V gets further regulated.

I designed a DC-DC supply that takes in +9 VDC and outputs ±15 V DC, +5 V and +3.3 V. I will check the design equations to see if I can reduce the bipolar output to ± 10 V without having to change the flyback transformer.  The little switcher I used for the +5 V out has a max out of +7 V (whew!). I can simply not stuff the +3.3 V LDO regulator.
 

Gene Pink

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Andy Peters said:
That explains the four-pin connector, though the manual for the mixer doesn't mention the +7 V requirement. That makes things trickier.
Since that supply is used for many of their products, perhaps it isn't needed in this mixer.

the wimpy 10mA +7V might only be a signal voltage with little or no filtering, to hold smart mute relay(s) out of mute. Lose power, mute relays relax and slam muted before the audio rails collapse, to prevent speaker voice-coil launching thumps. Yamaha used this scheme a lot, in outboard FX.
It would still be nice to know whether the ±10 V gets further regulated.
If it was regulated +/-10V going in, it wouldn't matter if it was regulated again on-board, but you already know that.

If you want my unsolicited advice, find a used PS-M1 supply on ebay. Last year, a used one went for $45.

Gene
 

radcomtech

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Aug 11, 2017
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2018 AUG update: I do not have 4 pin "plug" end for a PS-M1 replacement; I wish i had 3d captured that plug side because then I could replicate this plug using 3D PLA print at the local College (Student Center Store has both scan and print service, cheaper than I can do it in my Lab). The interconnect to the TASCAM is the issue at this time. Supplying with four pins 40thou sized is not good because the operator could mix up the exact connection sequence causing irreparable damage. John

I have a resolution to this PS-M1 issue.

I have a customer I am working for (August 2017) ,
and I have constructed a solution for a TASCAM TEAC MM1 Mixer PSU
using common isolated switchmode power supplies (two)
and an external board that supplies the +7 @ 10mA additional requirement.

I am willing to *construct* these PS-M1 replacements.

The design was successfully tested AUG 11, 2017 with a client TASCAM MM1.
The current drawn from the unit is less than 1/2 the full rating of PS-M1 but my
proposed replacement can easily supply 120 % rating.
Under normal loads the PS external PCB does not heat too much.

I ship either Purolator/USA or Canada Post and I am paid in PayPal only.
For interested parties, I may send an image, and a reference email to prove my integrity.

Anyone can contact me at radcomtech at  outlook dot com
I will not share the schematic unless you are a qualified CET in your Country, and shipping costs
are too expensive. I have one image of the project to parties interested in a custom built
replacement, and proof of its success that i can share, if you email me.
or by TEXT in Canada / USA at 613 706 9248

John Rad (CET-III, 1979, Ottawa Canada)

UPDATE {27SEP2017}:
I have received several replies at my IPphone (above) by text:

Answers to every question -> I charge $120 US to create:
the costs breakdown to 
two CISCO router Wall warts of 12V1A  at $52 (why? plentiful and negligible noise)
+ board with case to regulate +/- 12V to exactly 10V with filtering  at $24,
+ the strange British Q-type 1970's  4pin trapezoid shaped socketed end on 6ft cable $26 (now I cannot find any longer),
for a total $102USD in parts.
The rest $28 is *for me*.
Now I cannot find the 4pin, so I provide four 40mm hollow connectors to slip onto the TASCAM power pins
and *exact* detail of that [+10, -10, +7 Vdc and Ground]  pinout for the MM1.
I have made up four for Canadian owners, all 100% working . The resulting sub for PS-M1 is not pretty
but *safe* to put into a mixing table or cabinet...

2) if you guys know of a source of
"British or German Q-type 1970's  4pin trapezoid shaped socketed end power plugs"
please let me know...


30 JULY 2020 UPDATE:
I have been looking for someone to *model* the TASCAM POWER connector
in a 3D printer shape file STL format (3D Builder by Microsoft-Free). 

Two years after I repaired the four units, all four are still operational.
I used (eight) CISCO ACDC adapters and custom linear regulators (7810 & 7910&LM317)
on a small custom designed PCB. 
It was not a difficult build,
however !
one mixer was moved from one studio to another,
and there was some confusion on *pinout* when re-installing the mixer.

I found a supplier for those older inline Floppy Disk DC power pins; they fit perfectly.
UPDATE: look for AMP "MATE-N-LOK" "sockets" inside the IBM PC power connector
remove the 4 and use them right over the TASCAM power pins, They fit!

The PINOUT is
(upper left) GROUND
(upper right) +10 Vdc (red in the image below)
(lower left) -10 Vdc (yellow in image below)
(lower right) +7.5 Vdc (cant see that in image, internally regulated
                                                in MM1 as +5Volt for digital stages)

I used *two* separate isolated ACDC units with separate AC; this is _goofy_
but I chose this method because of the availability of CISCO Grey 12V 1A wall warts
and the prices here were $5 each. Any 12 =/- bipolar DC will do with common ground
that is isolated from mains-earth. The image shows AC blades soldered and insulated-
the mod is not CSA nor ULc certified, but
you can find bipolar 12V adapters on the market if you look.

I am disclosing this because I wont be making the PCB any further;
the museum TASCAM legacy items and PS-M1 are techno-orphans now.
The trapezoid DC input 'socket' is wider at the top , when viewed from rear of MM1.

Once I find the images from 3 years back, I will post them (minus the out-focused redactions).

2021 Update; I had another contact for a TASCAM TEAC 644 and that client was in my town . I had a week to study and document the PS-M1 port on the rear of the 644 MIDICENTER.
So a number of corrections and a new post will be at a link here:
https://groupdiy.com/index.php?topic=76901.msg978151#msg978151

 

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