Tascam M3700 Story...

Sadly, replacing the Voltage regulator chip had no effect. Fuse 2 is seeing exactly the same amount of power draw now that was with the old chip. I have 8 channels loaded in and the PSU is pulling 4.47A across the fuse. EXACTLY the same as before.

Curiously, while F2 pulls 4.47A, F1 is pulling 0.02A. F1 is the +15V rail and F2 is the -15V rail. Seems to me they should be more inline with each other...

A disappointing result after waiting nearly 2 weeks for the part. Not really sure what to test next... I need some time to think. I'm always open to ideas!

Robert
 
Well, Robert, awfully sorry to hear that.

Hm...

Silly question...you try swapping power umbilical cables to see if perchance the problem follows the cable?

And how about this...the heatsink with the rectifiers and all the transistors on it...are those identical between the two supplies and if so you try swapping those out?
 
Just to be sure...I would also disconnect that additional grounding scheme, at least at the common point, where they all come together, and at the power supply.
So you can have it at a "default" state. You can always reconnect them afterward.

That said....
I just bought two old AKG mics.
As soon as I got them, the "cat curiosity" got the best of me, and before I even tried them, I decided to unscrew the top to see the guts. These are dynamics.
I look inside, and then notice that there is also some kind of additional cover over the voice coil...some kind of acoustic guide. So I take it off (it's meant to be removed)...but as I pulled it off, I caught one of the hair-like wires coming out of the voice coil.
Well...that of course kills the signal from the coil. :(
So I try to reattach it to the contact point outside the mic, but some of it had broken off.
OK...I go get some super fine copper wire strands, of the same gauge, and connect it to the loose end...still no dice.
I then try to get a longer strand out of the coil, but I have to lift it just a tad to do that...but that doesn't work either.

Long story short...the repair just got uglier and uglier...until I reached a point where I knew there was no easy way to repair it...and I really didn't want to put any more time and effort into it, seeing how it only cost me $35 for each mic...and I still had one that was working fine.

Moral of the story...at some point you just may need to move on, but by all means give it your best shot before you do. ;)
You still have the 3500...and we already discussed options for creating a 32-channel version of it using the 3700 frame, so you have an alternative. Don't let obsession get the best of you, though I know what it's like to want to get something sorted out.

Personally...I wouldn't spend that much time/effort and money to get MIDI based volume automation...but that's me. I've had it, and never much used it. Maybe if I was mixing huge track counts...but 20-30 channels...it's no big deal to do that by hand, and it's fun. :)
 
Sweetbeats: I will try swapping the umbilical. I've not done that. The parts mounted to the heat sink are different between the two supplies. I assume the parts perform the same function but are under rated. I'm not comfortable swapping them out (yet).

Microslav, you and your voice of reason :) I'm going to try a bit longer to fix the PSU before I give up. I still have the M3500 and am not going to part with it until I'm sure I don't need it. What kills me is that the board works perfectly but the PSU is letting it down...

I have disconnected the grounding addon from the chassis and wrapped the wires to they can't contact anything but I'm considering de-soldering the wires from the buss PCB. At the very least I'm going to inspect them very carefully again to see if anything is connected across traces. Still though.. no issues when I use the M3500 PSU.

The gulf of difference between the current across F1 and F2 is most troubling at the moment. To my mind they should be nearly identical. Frankly the PSU rails in question don't have all that many parts on it. Perhaps it might be easiest to just swap them all out :)

More thinking, more testing. I don't need the board up and running for about a year still so I have to time to mull it over before I cut my losses and pimp out the M3500.

Robert
 
I don't need the board up and running for about a year still so I have to time to mull it over before I cut my losses and pimp out the M3500.

Oh...I thought maybe you were eager to get it going so you can use it.
Well then take your time if have the time. I don't want to push you to give up too soon. ;)

Last year I spent a couple of weeks on/off trying to fix some switch issues on an outboard EQ. Problem was the parts were hard to come by.
I managed to get it back to where the switches were useable...but I had to lose one switch to do it, for a function I wasn't using anyway.
So I put it back in the rack as-is....but was not 100% happy that I didn't get it fixed completely.
I've been meaning to give it another go when I have a couple of days to waste on it...which might be never. :D
 
Curiously, while F2 pulls 4.47A, F1 is pulling 0.02A. F1 is the +15V rail and F2 is the -15V rail. Seems to me they should be more inline with each other...


Robert
I'm not a technician but that does seem odd to me too!

Perhaps you could do a similar measurement on your M3500 board and it's power supply to see if you get similar lopsided results and if you don't, perhaps there is a clue in that somehow?

I'm getting an odd feeling that perhaps the mods that were done to your 3700, IE, the balancing kit perhaps is a possible suspect if that wasn't installed properly? Perhaps consider undoing that feature to see if that affects anything?

Good luck!

Cheers! :)
 
Not sure what state you're located in. Is the electronic gremlin search and cure the actual journey for you?

I've never had the time or desire to get into the tear-down and rebuild of tape machines and consoles. First sign of anything remotely resembling the type of things you're experiencing, I'd have the stuff into the car or truck and over to Tascam Montebello to let them deal with it. Which they do very well. Walk in, dump it in their lap, say "fix it" ... and they do. I've had my 85-16b over there a couple of times over the decades for things that go dead, and the guys have it back to me within a few days.

If you're primarily wanting to get going with music on this beast and only paid a couple of hundred dollars for it, the investment in giving the problem to Tascam .. or a tech they may suggest for your area.. is a pretty good investment as I see it. I'd pull out the little Cooper board and keep that safely in your possession when you do.

As a comparision to the $ investment you have in the 3700 so far, check this out. I paid $16,000 for my 32 channel board the minute it came out at the end of 1991.... $1,295 for the Cooper kit, $599 for the extended meter bridge for the console ... $399 for the meterbridge tolex overbridge unit that Tascam was making in 1994 (that one was a complete ripoff but I'm glad I have it).
 
Same here... :)

Bought my 24 channel 3500 in June of 1990 w/meter bridge for something like $8k...didn't bother with the Cooper stuff, but I got a similar automation kit from Niche, which was being sold by Steinberg/Cubase at the time. I was running Cubase on an Atari (still have it, working), and they introduced the Niche automation boxes and supported them with drivers/software...so I was able to control my Niche boxes via my Cubase sequencer...very cool.

I never saw the Tolex over-bridge thing from TASCAM...I just built my own. :D

And for the benefit of sr71rules...I'll mention this again... ;)
If you marry your console/tape with a DAW...you have NO NEED for console based automation, at all....at least I haven't seen any.
I set all my levels in the DAW when I mix out OTB through the console and my outboard processing. At the console, I fine-tune my levels, and *very rarely* touch a fader during mixdown these days.

While the Niche/Cubase automaton was *cool*...it just took a LOT of time screwing with it 'cuz I figured I can automate a gazillion little fader moves since I have "automation"... :rolleyes: ...but I found after awhile that it was much easier to just do it by hand for the couple of dozen channels....and the Niche boxes were not used anymore. I sold off the entire package w/the 16 channel mixing controller last year.
Now, with the DAW...all those little level adjustments are taken care of during my editing phase...so when I mix down, there's very little fader action.
 
I'm located in New Hampshire and would be willing to drop off the PSU and just pick it up fixed were there a local place that could do that. This part of the process is a step toward a fully working board that I hope will be trouble free. I am increasingly interested in older audio equipment though and would like to be able to make simple repairs on my gear. I am committed to using either an M3500 or M3700 as the center piece of my studio and once the snow melts I'll begin work closing in the studio space. I hope to have a board ready to be installed in about a years time; If the M3700 isn't working reliably at that time, the M3500 will be installed.

The M3700, beyond this PSU issue, is in better condition both cosmetically and functionally in comparison to the M3500. The M3500 has a problem on the XLR stereo out and has a lot of noise in the switches and knobs. Every single one of them is noisy and a lot of the switches work intermittently. The M3500 was in storage for 10 years, the M3700 has been in light but constant use. One of the two will be restored to 100% but I'd prefer to restore the M3700.

In terms of using the on board automation it's probably not something I will use with clients. I agree miroslav that it will be a lot easier to just use the automation in my DAW. Thus far however, the on board system works great and I'm intrigued by the system. I'm a Network Admin by day and I enjoy working with older, obsolete, technologies. My interest in the M3700's automation will not likely translate to a lot of session time using it. Assuming the M3700 becomes my main board I will no doubt play around with it but it's not likely I will depend on it. It would be reckless of me to ask my clients to depend on a system based on a computer that is 20 years old.

In terms of automating mixes, and not to derail this thread... I do automate a lot of my mixes, even if only faders. When a client comes in and wants to do 10 or 12 tracks I find myself bouncing around between sessions quite a bit and I just can't remember that on track 4, who's name has changed 8 times, I need to pull down GTR2 3db, 2 bars before the bridge. I just write it in. When it comes time to do the final mix down I don't have to read pages of notes and scribbles, I can just take a listen to the rough mix and work from there. I typically use touch sensitive motorized faders so setting them in update mode keeps making changes pretty easy. Different strokes for different folks. The automation system on the M3700, while pretty amazing back in the day, is not especially conducive to my preferred method of working. I can remember learning the automation system on the Amek 9098i, which also has non-motorized VCA fader automation, and just hating it. I can see myself making some use of the snapshot mode though, even if only to make sure nothing has been bumped or changed while I'm out of the studio.

I should have some time tonight to do some measuring between the two power supplies. Each day a little step closer to the solution.. or the garbage.

Robert
 
Same here... :)


And for the benefit of sr71rules...I'll mention this again... ;)
If you marry your console/tape with a DAW...you have NO NEED for console based automation, at all....at least I haven't seen any.


Keeping noise floor down, and also if you prefer the feel/taper of the analog faders--or just the tactile experience of making/writing in "real" fader moves. ProTools faders and mouse-click fader moves drive me crazy, plus when you automate levels down in PT and run it through an analog console, sure the source level goes down but not the console noise floor with it. The faders are probably my favorite part of the M3700. YMMV!
 
I just raise my signal level to counter any noise. :D

95% of the time, most of my tracks/channels are passing signal. For the occasional fader that stays up on the console during a no-signal section, it's not going to do much to *raise* any noise level perception...it's always there anyway, even when the faders are up and passing signal.

I wouldn't want to change the back round noise vibe but muting for a couple of measures here-n-there! ;) :)

I'm not doing string quartets or acoustic guitar-n-vocal stuff...so my sum signal is always well above the noise floor. I use to mute like mad when I had the Niche automation...it didn't make any noticable difference, unless the music dropped down to nothing...which it never does in the stuff I'm doing.

Plus, my main point was that it's easy enough for me to lean forward and press a few MUTE buttons manually on my 3500 with only a couple of dozen tracks running....as it is to program it in. If I was doing crazy stuff with 50+++ tracks...then I would appreciate some automation help.
 
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When it comes time to do the final mix down I don't have to read pages of notes and scribbles, I can just take a listen to the rough mix and work from there.

I know what you mean...but my point was that you can do all that automation in the DAW...no need to remember or make notes.

AFA the reliability of the 3700 automation/computer...you could always do the level automation in the DAW and simply use the 3700 automation for channel muting....to cut back on the noise floor, as briank as saying. That way you won't worry as much about the 3700 computer letting you down on a session.
 
I think it's pretty incredible that with the power of the internet I've manged to find these great boards, get help fixing them and hear from people who actually spend time on them. This is really amazing and I appreciate all the opinions and input. I look forward to forming my opinions and techniques as well on which ever board I end up installing.
 
Why do any of this you ask? If this works I can save my mixes as midi files and not have to worry about maintaining a large pile of 3.5" disks which I don't trust at all. When I want to go back to a mix I just load up the midi file and play it back in sync.

Maybe I missed something, but does your MAC have a diskette drive, or will it support one? Seems to me a simple work-around would be to save to a diskette, then save THAT to a file on your MAC. You thus only need a few diskettes, which you can use again and agin till they fail- then toss it and replace it with a new one.

Or, maybe I really DID miss something?
 
stevieb, let me go over a few things and add some clarifying information I've come across since that post.

The standard M3700 saves files to 3.5" Floppy disk. From reading the manual it says that the 3.5" floppy disk has to be formatted by the M3700 to be used and the file table used for the disk is, according to the manual, proprietary. Simply plugging the disk into a computer and copying a file on or off doesn't seem like an option. The only 'workaround' would be if I could convince a computer to image disks it believes are bogus.

The JL Cooper addon allows you to use a late model Mac computer as the 'brain' of the automation system and by extension allows you save you mix files simply as files to the Mac.

My M3700, with the addon, spits out all automation data via the MIDI out port on the console. I don't know if this feature is standard on all M3700s or if it's unique to models with the addon. The addon's only link to the Mac computer is Midi, no other data connection is made.

I have been able to source and get working a 20 year old Mac that runs the JL Cooper software and with that Mac I can save and edit mix files and, via an FTP application, back them up to one of my servers.

Were I unable to get an old MAc to work, or perhaps for better long term access, my idea was to just record the automation data flowing from the console as a MIDI track in my DAW. I should then be able to feed that data back into the console and have the automation happen without the need to use 3.5" disks or a dedicated vintage Mac...

The current condition of the console has precluded me from testing this last theory but my inner geek will, I can assure you, attempt to see if recording the mix as MIDI in my DAW will work. :)


The bit about the floppy disk format isn't something I knew when I made the previous post about saving the MIDI data. Further more, if I choose to use the M3700's automation, I will do just about anything to avoid using a 3.5" floppy disk. I really don't like 'em at all. :)

Robert
 
Personally, the auto computer in my 3700 was out when I got the board, but I got it serviced and since then it's been totally reliable, hasn't skipped a beat. I wish I could say the same about our ProTools rig :D

The diskettes don't bother me other than being old obsolete formats, though the flipside to that is I got several boxes of blank new old stock ones for free :D I agree it's a shame you can't really make backup copies of them as such, or at least as far as I can tell. I'm no 'puter wiz, though! You don't "need" a diskette for short term snapshot saves--the console will store the most recent snapshots for a short period of time as stated in the manual, but for longer term saves and for any dynamic auto saves, you'll have to save to diskette.
 
Were I unable to get an old MAc to work, or perhaps for better long term access, my idea was to just record the automation data flowing from the console as a MIDI track in my DAW. I should then be able to feed that data back into the console and have the automation happen without the need to use 3.5" disks or a dedicated vintage Mac...

The current condition of the console has precluded me from testing this last theory but my inner geek will, I can assure you, attempt to see if recording the mix as MIDI in my DAW will work. :)

That should work.
 
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