Tascam M520 Story...

  • Thread starter Thread starter sweetbeats
  • Start date Start date
Missing Jumper?

Hey cubsfan3075, welcome to Home Recording and congrats on the new M-520. They're great little consoles.

Your missing signal on buss 2 could be caused by a number of things, so first, lets start with the basics...

On the back of the mixer you should see a group of RCA inputs/outputs called "PGM ACCESS". There's 8 pairs of "RCV/SEND" jacks and when nothing is plugged into them, they should all have a little black jumper that connects the "SEND" to the "RCV". Do you have a jumper on "SEND/RCV" number 2? If not, then that's likely your problem... Swap a jumper from one of the other busses and put it on #2 and re-test. If it works then you just need to find a small rca cable or something to replace the missing jumper.

Give that a try and let us know how it how it goes...

-Tom.
 
Thank you for the response. You hit the nail on the head. I looked back there an there is in fact a jumper missing and swapping it did work. We had to carry it up some stairs and will look in my driveway for it. If not i can patch it with the a small RCA. Ive owned a few boards in my time but nothing with as much routing as this. Thank you again for your help on this. I really appreciate that. Would I be able to trouble you for 1 more bit of advice. Im running this to an 8 track tape deck and out of the 16 outputs that go to tape, im only using 8. I have an M-audio Project mix and I have the other 8 routed to that control surface. I havent tested it yet but will this run the tape signal to the control surface to import to mixing digitally instead of mixing from the board. Sorry if Im asking a lot. I got this Monday and she is quite a nice board and Ive been configuring all week and Ive configured to run outboard preamps and compression, just not to the digital realm yet.
 
Hey cubsfan3075,

Awesome... I'm glad it turned out to be just a missing jumper and not something more serious. I think it's pretty common for these M-520s to be missing a jumper or two. If yours has most of them then you're in good shape. :)

For routing signal the tape deck and your M-Audio Control Surface/DAW, you should be fine using the 8 "PGM OUT"s for both. The "PGM OUT"s (1-8) are your Buss Outs and there's two RCA jacks for each buss, so you can use one jack to send signal to your tape machine and the other to send signal to your DAW. To fly your audio recorded on tape into your Control Surface, you can connect the outputs (1-8) of the tape machine to the "TAPE IN"s of channels 1-8 on the mixer. Then assign the outputs of those 8 channels to busses (1-8), and then use your M-Audio DAW to record whats coming from the busses. This works great if you're combining tracks from the tape machine into one rack in the DAW, or using the M-520 to do additional EQing or processing with analog outboard stuff (like reverbs and compressors) before going into the M-Audio DAW.

There's also a direct out "D OUT" on each M520 channel too, that you can use to send audio directly from that channel to your DAW. This route would be a cleaner signal path since it bypasses the busses of the M520, and would work well, assuming you're doing a straight transfer of tape tracks to DAW tracks (and not wanting to combine multiple tape tracks to one DAW input.

There's a lot of different ways to hook stuff up with the M-520, and sometimes the best way kinda depends on what you're trying to do.

Did your M-520 come with the manual? They're pretty in-depth and handy, with all the parts and schematics listed. Totally good to have. They pop-up on ebay from time to time.

Post some pictures of the new mixer sometime... It would be cool to see. There's a good number of M-520 owners here on Home Recording and it's always nice to see another. :)

-Tom.
 
Very thankful for this thread! I have been trying to sort my way out to hooking up an M520 using ProTools 9 as the tape machine. I have good signal coming through the inputs then direct out to my I/O converter into PT; but having a real bear getting any reasonable playback level through the individual channel tape ins... wondering if the power supply could be to blame?
 
power supply verify

I started with the power supply check like sweetbeats did in earlier in the forum. The only inconsistency I found with my DMM was on pins 3, 4 & 5.

I found no DC on these relative to ground or relative to each other.
I found 2.8 VAC on 3 and 4 respectively (relative to ground; 4.7VAC relative to each other) and the same 4.7 VAC on pin 5 relative to ground and relative to 3 and 4 respectively.

Is this a problem?
 
bridge rectifier

looks like pins 3&4 are not getting any juice. checked the power trans secodary tap feeding through fuse 11VAC which continues to multipin connector and is also rectified to feed DC current to pins 3&4. It looks like there are a couple of bridge/fullwave rectifiers hanging off the inside, back wall of the unit, on the other side of the heat sink/radiators. There is no DC returning from this, so I am going to conclude that this rectifier is shot and hang a new one with ln4007s off the existing assembly.
 
must have been a typo- the 6vdc on pins 3 and 4 of the multipin connector from the power supply never showed up, but everything is working on it and on the board. perhaps it is a voltage return??
 
Shoooot...typed a big ol' reply and then inadvertantly lost it. :mad:

centervolume, its hard to follow what you are doing because you are kind of jumping around and making some assumptions, no offense meant. If you don't have the power supply schematic in front of you you really need to get it out...it has the pinout for the interface connector.

If you don't have that document you can view it here: https://www.torridheatstudios.com/documents/Tascam/Tascam%20PS-520%20Schematic.pdf

Notice that pins 3 and 4 are identical and carry +5VDC. This is for the LED's on the board. If they are working, its working. You should be able to measure about +5VDC from pin 3 or pin 4 to ANY of the ground pins on the connector (pin 8, 9, 10, 11, 12 or 13).

Your original problem...I can't tell if it is still a problem or if it is working now? If SOME of your audio is working then my first suspect is not the power supply because ALL of the audio is powered by one set of rails (+15VDC on pins 1 and 2 and -15VDC on pins 14 and 15)...those rails would have to be working in order for SOME of the audio to work. The exception to this would be if, for some reason, the rails were crapping out once you got to a certain current draw but I'm not thinking that's the case here. Oh...I guess I need to clarify that there is one other set of audio rails, the +18VDC rail on pins 6 and 7 and the -18VDC rail on pins 19 and 20 which ONLY powers the line amps in the BALANCE AMP section behind the master section.

Also notice pin 5 is not connected to anything...there should be no voltage there, but be careful in case somebody added something to that pin at some point. It should be vacant.

I don't know what you mean by "voltage return."

If a rectifier is shot I'd replace it with a new integrate part unless you really want to make it discrete with 1N400x parts...note that the parts hanging on the back wall of the supply are mostly regulators, either transistors or integrated parts...don't have a pic handy of what's back there and the schematic doesn't make it clear but my point is that you need to cross reference with the schematic before you just assume what's what back there.

So let me know if you are still having an audio problem because I would point you to the monitor section and how you have it setup. If you are still having trouble I'll star5t asking you some questions about you you have stuff setup and then we can either kill the problem there or hone in on the culprit.
 
Yes, like you I also felt that even if I couldn't measure the voltage on pins three and four that, if things seemed to be functional, that it was ok to leave well enough alone.

I have gotten through the problems posted above and most of them were caused by my cables. I had trs to trs laying around in large quantities. So I got a bag of RCA male ends and went to soldering. Initially I reversed the tip and ring- this resulted in the input signal working but not the playback. I reversed those leads and got the playback signal but with feedback problems in the main channel faders and EQs. I realized that the 3 conductor cable in a 2-conductor/ unbalanced application was causing the cable to act as a capacitor. I made up a couple ts RCA to 1/4" cables, put them in to ch 1 and all the feedback is gone from that channel. Now this leaves 16 more cables to fix. Wondering if I just clip the ring conductor from the RCA end (where it is currently tied to the braided shield) if that will make the cable operate as it should- even though the trs end still has the ring conductor connected?

Only one way to find out I guess.

My interface is two echo audio fire 12 s daisy chained. They allow for balanced or unbalanced operation with all 1/4" I/o.
 
centervolume said:
Yes, like you I also felt that even if I couldn't measure the voltage on pins three and four that, if things seemed to be functional, that it was ok to leave well enough alone.
Click to expand...

I wasn't saying I couldn't measure voltage, I as just guiding you to what you shold find when setting your meter to DC volts and probing between pin 3 and ground or pin 4 and ground.

centervolume said:
I have gotten through the problems posted above and most of them were caused by my cables. I had trs to trs laying around in large quantities. So I got a bag of RCA male ends and went to soldering. Initially I reversed the tip and ring- this resulted in the input signal working but not the playback. I reversed those leads and got the playback signal but with feedback problems in the main channel faders and EQs. I realized that the 3 conductor cable in a 2-conductor/ unbalanced application was causing the cable to act as a capacitor. I made up a couple ts RCA to 1/4" cables, put them in to ch 1 and all the feedback is gone from that channel. Now this leaves 16 more cables to fix. Wondering if I just clip the ring conductor from the RCA end (where it is currently tied to the braided shield) if that will make the cable operate as it should- even though the trs end still has the ring conductor connected?
Click to expand...

You aren't using insert jacks as I/O on the Echo units are you?

The cable should not act as a capacitor in any appreciable way...any decent cable has only picofarads of capacitance per foot.

Consult your Echo Audiofire manual to confirm, but normally a TRS to RCA cable with 3-conductor wire would simply have the ring and shield conductors bonded to the the shield of the RCA plug and tip of the TRS to the tip of the RCA.
 
I am using direct out and tape ins. I am running the mains out of stereo outs A into powered monitors. So the mic or line in, the direct and tape i/o and the stereo outs are the only cabling I have at the moment.

cable capacitance is the only explanation that made any sense. Whatever the actual reason is, using unbalanced cables for my application is eliminating the feedback in channel faders and EQ. It just sounded like there was too much gain.. even at 0 on the channel fader, I could get feedback by boosting the EQ gain and then shift pitch as I adjusted the EQ frequency control. At flat EQ, it started as a very high frequency feedback when the channel fader got up to about 80%. It was a pretty limiting condition. In any case, it is the latest issue that has been taken care of... even if I can't totally explain it.

Now I need to figure out if there are special considerations for over dubbing.

I will be adding analog processing (compression, effects and some mic preamps) - with the ultimate goal of recording early rock'n roll groups live in the studio. The m520 strikes me as well suited for this application, but it is also my first studio rig. Being on this side of the desk is all pretty new to me. Each issue troubleshot feels like a major victory! thanks again for this thread, it has been helpful.
 
The thought definitely crossed my mind until I heard the performance with the unbalanced cables- just beautiful analog sound, really amply better than I had anticipated by a good bit. With the proper cables between the board and converter I can get the board wide open on trim pot master channel fader eq boost across all frequencies and buss masters as well. And it stays clean.


I lifted the ring conductor on my cables to see if the trs
Would act like the t-s cables and in fact they still resulted in feedback. So I have one channel wired up with t-s in and out and it is super clean and beautiful sounding. If I move those cables to other channels then those channels are perfect. Replacing the trs cables the channels get real unstable and feedback again. This ofmcourse blew my cable
Capacitance theory out of the water. Now the best can come up with is that the converter is reacting differently to trs ends than to ts ...?
 
Cory,

I'm trying to clean my M-520 and my faders look like the one on top:

IMG_7212_5_1_1.JPG


I can't figure out how to break them open to clean them... the housing seems to be pinched shut in a pretty permanent kind of way. Did you ever disassemble them to clean them?
 
I never did on the M-520 but my Soundtracs MX console has the same ALPS faders and they are pretty easy to open up...lemme see...

AHA!

I knew I'd put up some explaination about it...go here...post #63 in my "Cleaning Faders" thread. Let me know if that doesn't spell it out clearly enough.
 
Calling on Sweetbeats! I have watched this thread ever since I acquired my M-520 3 years ago. I knew the time would come when I would need to recap. Well, the time has arrived. I recently bought an M-512 with the idea that I would use the M-512 in my studio until I was done recapping the 520, but as ebay purchases go, the 512 was in worse shape then my 520. So, I have decided to recap the 512 first. It's smaller and does not have an external power supply. This thread is a little overwhelming. I'm gonna start by recapping the first 4 channels. Can you (Sweetbeats) drop me a link to the caps you used for the first 4 channels. I know there are all kinds and values. I don't know much about this kind of work...although I have made cables, and done minor repairs in the past but nothing like this. I trust you fully, sorry if this is a little redundant, but maybe there will be more guys like me in the future who are not savvy with electronics and need some striped down instructions. Thanks so much
-Kenny
 
You want instructions or a list of caps?

Not sure exactly what you are asking for.

Do you have a manual?

All the caps are listed there.

Are you having problems that point to the need to recap?
 
Hey Sweetbeats! Thanks for the reply. Yes I have the manual, those guys must have went to college! I'm having the same problems you were and then some. Two channels straight up quit working. Here's what I'm hoping to can help me with...In laymen's terms ;-) And I apologize in advance for not using the correct terminology! I'm going to take this recapping process slowly. Also, because i'm a visual person, I will post pics of my progress and questions as they arise. I will practice on the spare parts board that I have before I do the real thing. That's right...I have a parts 520, working 520 and 512. I'm a big Tascam fan, so its about time I get my hands dirty, especially because no tech near me will touch it.

What kind of caps are needed for the channel card? (what are they called) C1, C2?
Can you provide the links for each cap? (so I can just go to the site and order them)
How many caps per card?
I'm comfortable using the same caps you used.

Thanks again! Excited/nervous to do this.

here is a pic of the spare channel strip I'm gonna disassemble...practice makes perfect! photo.webp
 
I'm gonna make you do some of the work. Open your manual. Look for the picture of the input ampl. PCB and close to that should be a parts list. Fun the capacitors section. Now make a list of all the electrolytic caps on the input amplifier boards...they will be denoted with "elec." in the parts list. Post it up here. I'll check it, and then will help with links. But you gotta get your hands dirty in the manual first getting comfortable looking around for stuff okay?
 
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