Tascam M3700 Story...

Pages 51-52 of the 3700 binder (not the later schematics section), show the midi protocol for sysex, vca moves, switches etc that appear at the midi in/out of the console. That's the crux of the communication to the Cooper computer and also the communication that was used to demo the old "Faderview" floppies at Namm/AES shows etc. Faderview was basically the crippled version of the Cooper program. No editing of what you see.

The manual shows that you can send the fader and switch moves out of the console to an external sequencer and then play that back to control the vca faders/mutes.... but ... I think it's the offline, after the fact editing, that is where the Cooper capabilities come in. That would also seem to be where the gui of the Cooper program is helpful.

But hey ... I'll keep a watch on this thread as this type of stuff is fun to read.

I was also taking a look at a newer Mac here and the "two colors, two grays" thing you mentioned way back at the beginning. Were you running system 7 on that first Mac?

Also out of curiosity, is your Cooper software version 1.01 ?
 
I am running PRO3700 v 1.01 and my Macintosh LC is currently run System 7.5.3. I tried to launch it on OS 9, System 8 and then, with the LC, System 6 and 7. I first tried it on a B&W G3 then a PowerMac 8500/120 and then I broke down and bought an LC on Ebay. The issue I was running into is that the newer machines were unwilling to run at a low enough color palate. The LC is the first machine that allowed me to run the OS is something lower than 256 grays.

I agree completely about the offline aspects of the JL Cooper addon. The ability to make offline edits is the core of what the addon brings. Seeing fader positions is, as you say, possible with the free 'Faderview' program that works on any M3700. The down side there is you have to do it in text. You would, for example, pull up the 'Create Fades' window and then specify the channels, volume levels and time code points for the fade.

Create Fades.jpg

Saving a mix via midi would make manual edits... much more difficult :spank:

It would be a fine way to save the automation information of a mix without needing to rely on anything other than the MIDI spec though...

Robert
 
Since the Cooper circuit card and console do the work and the connection to the outside world is midi, I wouldn't be surprised if some enterprisiing kid who knows c programming or 68000 decompiling couldn't whip up a windows gui version of this in about ten minutes just by taking a look at the code on the floppy. The program isn't exactly rocket science.
 
You can. I've done it.

PS-3700 has an extra power rail for the automation system and it's rated for 200Watts, instead of the 170 watts of PS-3500 but it will work just fine. The umbilical cord is the same.
 
Just a quick update:

The M3700 project is still happening but it's had to take a back seat to a few other things going on. I won't get into a lot of detail but having my house burglarized wasn't a lot of fun, not is it the most pressing issue I've been dealing... Not to worry though the geniuses took lots but left all the good stuff :) No audio equipment was taken, with the exception of some cables.

Onward and upward though! I'm not having a lot of luck fixing the power supply and it's time to let a professional take care of things. My dad recommended a local electronics guy so I'm going to give him a ring and see what he thinks. I'm not sure what the problem is, but I am nearly sure it's the PSU and not the board. I've done enough testing to satisfy myself on that... Hopefully he will be able to fix it!

Once I'm confident in the M3700 I can finally sell the M3500 that is soaking up a lot of room in my house :) It's a great board that has been running well for several months now but the M3700 is the one I want to keep as my main console and I'd rather recoup some of the costs from that board then store it. I've been using the M3500 has a stereo, moving my iPod though it's 32 channels and 68 total inputs and it's been working great. Assuming I can find a local(ish) buyer it shouldn't be hard to sell, especially considering I have 8 spare channels to sweeten the deal...

More as it happens!

Robert
 
Professional Help!

The local electronics guy didn't seem to knowledgeable about the world of 'Pro' audio gear so I passed on having him take a look at my power supply. Then, just by chance, I was reading a post over at Gearslutz about a guy who had a pre-amp modified by some place called 'AudioProz'. In his post he mentioned he had to ship his item over to Boston, MA and I immediately did a Google search to find out where it is. Turns out it's some guy running a shop just outside Boston, in Watertown, that basically fixes all kinds of electronics. I sent him an email outlining my problems and to my huge surprise he knew all about the M3700 boards and even sold a few, new, back in the day. When I called him up he started going on and on about all the mods he used to do on the boards and how much he liked working with them. He was asking me all kinds of questions about where I got it, what kind of music I'll be working on with it, ect, ect. It was great! I drove down to his shop this past Saturday and dropped of my PSU and when I arrived I was totally blown away!

The place is a tiny shop along the road and its filled, as neatly as could be done, floor to ceiling with electronics gear. Racks of gear with everything from old spring reverbs to a DBX 160SL (just sitting in a rack inches from the floor where a single mis-step would break a knob or two off the front). The shop has a bunch of techs, looked like mostly 20 something guys, just working away on gear, soldering irons in hand. Clearly, I've found my source for local tech help!

They asked me a few questions while manually filling out some paperwork and handed me a little paper claim check. I handed over some money and they said they would be calling in a few days. I cannot wait! I suspect that when I leave their next it won't be with just a PSU in hand. A few other items caught my eye...
 
That sounds like a GREAT shop! Wish we had something like that around here! "Hot rod my record and repro cards, pleasuh!" :D


BTW I've never used a DBX 160SL, but it had better doggone well be pretty awesome if it's in Manley Vari-Mu/A-Designs Nail price territory!
 
I've never been a big fan of the 160S or 160SL but I'm sure it has it's following. I was really surprised to see it sitting 1U off the floor though :) Like it or not it's still expensive! It was a great place to visit but I'm glad it's slightly more than an hour away.. otherwise I'd be there every day!
 
The M3700 is Alive!

I picked up the Power supply this past Saturday, plugged it in and voila! It's working normally.. so far at least :)

Couple of things to note for anyone running into similar problems at some point. Firstly, the power supply wasn't 'broken' per say. The tech did not replace any parts. Basically, what he said was that due to the age of the unit some of the solder joints were stiff and cracking enough to not make strong or consistent connections. This in turn was causing certain parts to pull too much power and blow the fuse.

Also, he added several new 'ground lines' to the unit for me. One off of the ground tap on the transformer and another from the ground of the power supply's PCB. He added little pig tails that I can then attached later should some ground issue result. He explained that I should use the one on the transformer to help with the noise floor, if it's and issue, and that I should use the one on the power supply's PCB if I get ground loops when wiring in gear. He said to ground that line to the same place my rack units get grounded. He was really helpful and, so far at least, successful at fixing my problems.

He said that the board could still be having issues and that I should check each channel's signal path to look for anomalies. If I feed in a sine wave and the output is distorted in some way a part could be bad or soldered poorly. It's a distinct possibility since the first 16 channels were modded to new opamps.

Much testing to follow!

Step one however is going to be to swap the M3700 into the space the M3500 is sitting so that it's more convenient for me to work on. I'll be needing to trick some friends into helping with that.. it shouldn't be too bad a job frankly considering the boards are pretty well disassembled at the moment...

As I powered up the board and waited and watched for a popping fuse it occurred to me that I've never actually heard any audio the board has passed...

Since it stayed on without issue for a few minutes I wired in my iPod and some headphones.. hooray! It works! Some scratching pots in the master section that will need exercising, no big deal. Faders in 'bypass' mode sound less full than faders not in bypass mode. The non-latching EQ in buttons and mute's are noiseless, something that can't currently be said for my M3500 :)

So many questions and sound samples to try out. I also can't wait to compare the modded channels to the stock ones...

So excited!
 
VERY COOL that you got things working!

I have a spare PS for my 3500...but nice to know that if issues arise, just redo all the solder joints first.

sr71rules said:
Also, he added several new 'ground lines' to the unit for me. One off of the ground tap on the transformer and another from the ground of the power supply's PCB. He added little pig tails that I can then attached later should some ground issue result. He explained that I should use the one on the transformer to help with the noise floor, if it's and issue, and that I should use the one on the power supply's PCB if I get ground loops when wiring in gear. He said to ground that line to the same place my rack units get grounded.
Click to expand...

OK...I'm interested in the ground mods. I understand about the second ground going to the the rack gear ground if needed...but where are you running the tranny ground wire to?
I recall that board already had some grounding mods internally...are you attaching the tranny ground to that existing stuff or something else?
 
I'd be wary about running any chassis grounding between the mixer and a rack. All units in the rack should tie back to the same building ground as the mixer. If you start connecting chassis together and there is any possibility that they are also tied to the building ground in any way, then that strap from the mixer to the rack becaomes an antenna.
 
After dealing with safety grounding issues on my Ampex MM-1000, drastically updating the grounding on my 32 x 8 Soundtracs MX mixer, and now preparing to mod the grounding on my MCI JH-416 console I see proper grounding for a mixer in sort of 4 phases:

  1. Building Ground: your breaker panel needs to be properly grounded according to local code. This is ideally a big ol' groundstake driven into the ground and a big ol' wire running from the ground buss in the panel to that stake. Where I'm at it is TWO 8' stakes at least 6' apart. Once you can confirm that the panel is properly grounded then you ideally ought to have one circuit just for running your audio gear, and have one place where that circuit is accessible. I have a 2-gang box with 4 outlets on the same wall as my mixer and that's where all the audio gear gets power. Its on its own breaker...nothing else but that 2-gang box is on that breaker. I have three power distribution units plugged into that set of outlets. That's A-OK. All three distribution units have 3-prong plugs...everything is tying back to that one path to ground.
  2. PSU/Mixer Frame Bonding: this is assuming we're talking about a mixer with an external power supply. The building ground should securely and positively bond to the chassis of the power supply at a point as close as possible to where the power enters the power supply. The mixer chassis should be referenced to the PSU chassis so that the mixer chassis ALSO ties back to that single ground source. The ideal way to bond the PSU and mixer chassis together is over the interface cable that connects the two together, and ideally it should propogate over a braided shield in the interface cable. So the shield should bond to the PSU chassis in the PSU, again as close as possible to the interface connector, and then likewise the shield should securely bond to the mixer chassis as close as possible to the interface connector inside the mixer. Part of this step also deals with the 0V DC rails. Care should be taken to ensure that the 0V rails DO NOT bond to the PSU chassis, but rather bond to the mixer chassis at the same point where the PSU to mixer chassis shield bonds in the mixer. If you set it up this way then both PSU and mixer chassis are referenced to the building ground (at the same point as everything else in the studio) AND your DC power rails are referenced to that same ground...nothing is floating, nothing is looped, but notice the 0V rails reference the building ground in the mixer...this is so that interference picked up along the length of the interface cable is shunted back to ground up in the mixer rather than shunting in the PSU (if the 0V rails were strapped to the PSU chassis)...if you tied them in the PSU then anything picked up along the length of the interface cable would have the potential of causing issues.
  3. Mixer Frame Bonding: now you want to make sure that all metal portions of the mixer frame are positively bonded together and especially back to the section that is strapped to the PSU chassis which is the path back to the building ground. This is for safety, for dealing with environmental noise, and for ensuring that there is a ready place for your audio grounds to bond as described in #4...
  4. Audio Pin 1/Shield Grounding: bottom line here is that all TS/TRS shields and XLR pin 1 terminals should bond to the chassis as close as possible to the jack. That's it. Any length of wire in between a shield or pin 1 terminal and the chassis is an inductor...a potential point of noise infiltration. So have a look at how it is handled in your mixer. I don't know about the M-3x00 mixers. I know they have jack PCB's which makes it tough to strap each jack to the chassis...you kind of have to take each situation and devise the solution. In my Soundtracs mixer, which has jack PCB's of 8 jacks each, a wire was run from the ground plane of each jack PCB to mixer chassis in such a way as to minimize the length of the wire. The whole point here is to provide a short path from the signal shield to the chassis which is properly referenced to the building ground.

If your mixer is setup as above, it is in good shape to deal with environmental noise, and is properly configured to interface with other gear and to have a consistent way to deal with ground loops. If you DO have hum or excessive interference noise when hooking up a particular piece of gear then the ideal thing to do is to determine how the manufacturer of that gear dealt with signal grounding and fix it so it is consistent with the mixer. If that is not realistic or possible then the bandage fix is to lift the shield of the audio cable at the end of the external gear. Don't lift the shield at the mixer end! If you do then the shield, which naturally is picking up environmental noise, will pipe that noise into the signal through the external gear and into your mixer. By lifting the shield at the external end you are leaving the "antenna" connected to the mixer which is properly setup to deal with that noise. In the ideal world you would never have to lift a shield. That's why I call it a bandage fix...its a solution to deal with inconsistent or improper grounding conventions.

Hopefully this helps to clarify why you may be asking for trouble if you start strapping the mixer chassis to an external rack or some such thing...you are inviting a big-ol' ground loop unless you can ensure that NOTHING in the rack is tied to the building ground but how realistic is that?? And not only that but it is not the safest measure either since the lowest resistance path to ground for any of that external gear will be its power cable (assuming it is a 3-prong cable).

Crack open that M-3x00...I have a hunch the audio grounds are "star-grounded". That was my Soundtracs mixer...I think there was about 12 YARDS of wire between the shield/pin 1 terminals and the chassis. Nice antenna.
 
I think he was talking about tying the P/S PCB ground to the same place the rack gear is grounded to...not the mixer chassis.
I would assume the rack gear is grounded back at the A/C power source via it's 3-prong power cables, so the P/S PCB should already be grounded to the same power source...right?

I'm interested in where/why it was suggested that the P/S tranny ground is going to go....???
 
miroslav said:
I think he was talking about tying the P/S PCB ground to the same place the rack gear is grounded to...not the mixer chassis.
I would assume the rack gear is grounded back at the A/C power source via it's 3-prong power cables, so the P/S PCB should already be grounded to the same power source...right?

I'm interested in where/why it was suggested that the P/S tranny ground is going to go....???
Click to expand...

Ah. I see that now (the reference to the grounding of the rack gear...)

And, yeah, I guess I pontificated because I've learned that you can't just throw solutions willy-nilly at grounding problems...solving ground problems is really actually very simple and methodical, and methodically simple...IOW it is a definitive process.

I guess I too would like to know more about what the tech did...it just makes me itch a bit, what I'm reading.
 
Hmm. Now I'm curious too. He relayed the information to me verbally so it's possible I missed the point...

As I understand it, the ground coming off the PSU PCB is to be used if I get a ground loop when using rack gear with the board. Basically, if my ground wiring isn't great 'in the walls' and an issue arises when I'm using some piece of rack gear, wiring a ground from the console to the same place as the rack gear should help solve that.

Secondly, the ground line coming off the transformer, as I recall, was to be used if the console itself exhibits some sort of ground hum. If the power coming into the board is bad and looping somewhere, grounding it properly before it goes through the rest of the PSU and then the console can be done with the transformer's ground tap.

Neither ground line is supposed to just be wired up. My impression was that should an issue arise, I could use one or perhaps both ground lines to help mitigate the problem. He did not add any wires that connect back to the console. All console to PSU connections happen through the umbilical cable and all of the boards internal grounding work ties back to the ground wire within that cable.

Does any of that make sense? I can call him to clarify if you think I've got something wrong. Either way, I'd like to document what they should be used for so that in a week when I've forgotten I'll have something to refer to :)

I've never had any grounding issues in my studio, I'm nuts about electrical wiring, and I didn't ask him to perform those tasks. He seemed super knowledgeable about audio gear and the M3000 boards specifically so when I dropped of the unit he said he would do some common ground mods that others have needed in the past. He basically rewired the whole unit so I suppose it was one of those 'Since I'm already here... ' sort of things.

Would I be correct in not using them unless an issue came up? The PSU itself does have a 3 pin power cable...

Robert

(Also, thx for your grounding explanation Sweetbeats. Solid stuff! Gave you some rep points for that!)
 
Hello Robert
Could you send me a higher res of this schematic please, i am a new member and i am looking for a clear drawing of this powers supply.
Regards
 
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