Tascam M520 Story...

  • Thread starter Thread starter sweetbeats
  • Start date Start date
Tijs, good job.

Your M-520 actually appears to be in good cosmetic condition as you stated. From the picture you put up the jacks actually look pretty good to me.

You won't short the PS by testing with a multimeter, but since you are getting audio through the desk I wouldn't go poking around just yet with that multimeter, not that it wasn't worth purchasing.

If you are able to hear a soloed channel, and you were able to monitor the input at the SPARE jacks then we know that your 15V rails are working. The 15V rails power all the operational amplifiers in the mixer. You're getting sound so they are working.

Tijs, DO YOU HAVE THE MANUAL??

There is no activity on the meters though with the right selections.
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So with the STEREO A/AUX 1-2 meter select switch set to STEREO A, the Korg connected to the SPARE jacks, the SPARE button latched in the MONITOR SELECT switchrack, and the STEREO A MASTER fader in the shaded area, you can play the Korg, hear it in the headphones but there is no meter activity? If you connect your monitor speakers to the STEREO A out jacks can you hear the Korg in your monitors?

Also the channelstrip work when I use solo (the led lights up too now).
The EQ section works too. The trim has no effect but this has something to do with the Line input (works only on MIC?)

No succes on the busses yet but I'm in a positve mood now.
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Please list in detail the connections and settings when you are trying to monitor the Korg through a PGM buss.

The TRIM knob is in two sections...it is a stacked pot, right? The top one (the one that has the colered cap on it) adjusts the MIC input. The lower one adjusts the LINE and TAPE inputs. Is that the one you are using with the Korg connected to the LINE jack?

Have to say that the base (white)noise is quite high (even with headphone volume down), hope this is only on the headphone out.
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Not likely...if you hear it in the headphones there is a good chance that you're going to experience it in other outputs as well, but there are a number of factors that can cause noise:

  • Bad capacitors...the M-500 mixers are old enough that the capacitors are often worn/dried out/bad. At the least this can contribute to the noise floor. I'm talking about caps in the power supply as well as the mixer. You may be able to improve things by replacing the capcitors in the power supply first. That's the advice I've generally received is to start there.
  • Dirty contacts in switches, pots/faders. I'm dealing with that right now on my M-520...I'm having particular trouble from the channel ON switches and ASSIGN switches, as well as the source select switches. Spraying DeoxIT into the switch and exercising the switch usually takes care of the problem, and to do it right you need to remove the channel module and remove the cards from the panel.

Don't let it get you down. It is totally common. There's a reason you can get something that sold for $7000USD 25 years ago for literally pennies on the dollar...it takes time and TLC, but at the end of it you get to know your gear inside and out and you can get it running well.

One of the hardest things on capacitors is lack of use.
 
Yes I have the original manual, i read it too, very well documented but on the other side very technical and my english is not that good.

I checked the spares again I had the wrong fader up: Meters are working.

I indeed connected it to the line this time (won't plug my synhties in XLR's anymore for sure :D

De lower part of the trim pot does not seem to have any effect, but I think this is due to the fact that it's in solo (maybe bypassing the TRIM then) so I only hear it too when turning the solo pot up.

I tested the busses as follows (tried different buss/channel combis):

Jumpers on channel 1-10 and all PGM SEND/RCV

Line in on channel 5.
PHASE: norm
INPUT: line
TRIM: lowest pot 3 oclock ( I see top is MIC lower is TAPE so maybe line in can't be controlled by TRIM or tape in and line in are shared)
ASSIGN: only buss 1
ON pressed (LED indicates)
Channel volume grey area

MONITOR SELECTOR: only MON pressed

MON 1: switched to buss (the rest center), level 12 oclock, PAN middle

Buss fader 1 grey area.




Unfortunately I have no RCA to XLR to hook my dyns up to test the Stereo Master Out. Will try to buy these after my work tommorow.

About the noise; so bad PS caps can be the cause. Isn't it dangerous to cut these out (high current stays in the cap also power disconnected)? Otherwise I will unsolder them and buy new ones.

The ON and solo switched are also problem on this desk. Audio is coming in and is sometimes louder, sometimes falls out. When I tick against the on switch audio is coming back.

Also the EQ knobs cause sound to become louder, less louder in an abnormal way.

This weekend I will dissmantel it (including removing the cards) and start with undusting the pots,faders and switches with compressed air spray. I will buy the DEOXIT to spray this afterwards (to prevent dust pudding on the pots).

Didn't realised it was so epensive back then. I thought is was a budget model these days (very strong build though). I paid 400 Euros for it which is about 460$. Not bad then. I can also buy a MSR-16 from the same guy mint condition 200 hours for 300 euros. But I think 1/2 " 16 track is to less tapewidth for the channel amount. I think I will try to buy a Revox PR series stereo recorder which are supposed to be very good.

My setup will than be: synths, analog filters --> fireface/AI3 IN ---> Fireface/AI3 outs---> M-520 INS & Monitors ---> M520 stereo outs ---> Revox --> Revox back to Fireface for rerecording in Ableton.
 
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Yes I have the original manual, i read it too, very well documented but on the other side very technical and my english is not that good.
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Good. Thanks. Let us know if there is anything from the manual that we can help explain, or if I am not being clear ("I don't understand you" is a perfectly acceptable thing to say to me... :D:D:D)

I indeed connected it to the line this time (won't plug my synhties in XLR's anymore for sure
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Just keep in your mind what evm1024 said about using the XLR's. He is right. You can use any input, but it is better to use the most appropriate input...the one that matches the normal level of your source (mic, line, instrument, etc.). Otherwise you are putting your source through circuitry that may be unnecessary.

De lower part of the trim pot does not seem to have any effect, but I think this is due to the fact that it's in solo (maybe bypassing the TRIM then) so I only hear it too when turning the solo pot up.
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The SOLO and PFL circuits are "post-trim", so what you hear in the headphones or monitors connected to the STEREO A buss when soloing an input will be effected by changes made to the TRIM knob. Not sure why that is not working for you. Do I understand correctly that you tried the LINE inputs on multiple channels?

I see top is MIC lower is TAPE so maybe line in can't be controlled by TRIM or tape in and line in are shared
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They are shared. The lower TRIM knob adjusts the TAPE or LINE in jacks according to the block diagram on page 15 of the manual, and also according to section 6 on page 18.

I tested the busses as follows (tried different buss/channel combis):

Jumpers on channel 1-10 and all PGM SEND/RCV

Line in on channel 5.
PHASE: norm
INPUT: line
TRIM: lowest pot 3 oclock ( I see top is MIC lower is TAPE so maybe line in can't be controlled by TRIM or tape in and line in are shared)
ASSIGN: only buss 1
ON pressed (LED indicates)
Channel volume grey area

MONITOR SELECTOR: only MON pressed

MON 1: switched to buss (the rest center), level 12 oclock, PAN middle

Buss fader 1 grey area.
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Just to confirm again: when you are trying to monitor through the PGM buss, nothing is soloed right? I'm only asking because this has fouled me up several times as I've been getting familiar with navigating the M-520... :o

Try this:

  1. Take unused jumpers (jumpers that are plugged into channels you are not using) and plug them into the PGM SEND/RCV jacks so that all 8 PGM busses are jumpered.
  2. Switch monitor channels 1 ~ 8 to source BUSS, LEVEL to 3:00, PAN center.
  3. Raise PGM BUSS faders 1 ~ 8 to the shaded area.
  4. As before make sure nothing is soloed, the correct input jack is selected, the channel is on, the channel fader is in the shaded area, and that the MON switch is latched in the MONITOR SELECT switchrack and the headphone knob is set to a comfortable level.
  5. One-by-one assign the channel connected to your synth to each PGM buss (i.e. first route to just buss 1, then to just buss 2, all the way to 8).
  6. Anything?
  7. If yes, report what you got where.
  8. If no, switch the monitor channels 1 ~ 8 source select switches to center/off.
  9. Switch monitor channels 9 ~ 16 to source BUSS, LEVEL to 3:00, PAN center like you just did above with 1 ~ 8.
  10. Repeat step 5.
  11. Anything?
  12. If yes, report what you got where.
  13. If no, try connecting the synth to any of the SUB IN PGM jacks in the master section. That is a direct patch to the PGM buss faders (i.e. if you plug your synth into the PGM 1 SUB IN jack, set monitor channel 1 or 9 to BUSS, LEVEL to 3:00, PAN center, MON switch latched in the MONITOR SELECT switchrack, PGM buss 1 fader to the shaded area, you should hear the synth in the headphones...kind of like the direct route the SPARE jacks have to the MONITOR SELECT switchrack as opposed to going through a channel strip, but with the PGM SUB IN jacks the signal still goes through the PGM fader, monitor mixer LEVEL and PAN knobs before it gets to the MONITOR SELECT switchrack.
  14. Anything?

Unfortunately I have no RCA to XLR to hook my dyns up to test the Stereo Master Out. Will try to buy these after my work tommorow.
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No need...see the BALANCE AMP section on the back of the mixer behind the master section? That is a separate 8 unbalanced signals in on RCA jacks that go to the 8 balanced out jacks on XLR's. Changes any -10dBv line level source to +4 or +8 dBu balanced output whether the source is from an M-520 output or anything else...cool, huh? So, connect a pair of RCA cables from the OUTPUT ST MSTR A jacks to BALANCE AMP INPUT jacks 1 & 2, and then connect a pair of XLR cables from the BALANCE AMP OUTPUT jacks 1 & 2 to your monitors.

About the noise; so bad PS caps can be the cause. Isn't it dangerous to cut these out (high current stays in the cap also power disconnected)? Otherwise I will unsolder them and buy new ones.
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This is true...I've never gotten a clear instruction on how to properly discharge caps...Anybody? :confused: They do discharge over time, and it is much more a concern with big caps that are in the power supply. Tijs, if you are going to recap anything, just start with the power supply, and yes, you'd want to be careful of cherges stored in the caps...maybe unplug the PS-520 from the mains and then switch the PS-520 ON with it connected to the mixer? Wait for a some better advice on that one.

The ON and solo switched are also problem on this desk. Audio is coming in and is sometimes louder, sometimes falls out. When I tick against the on switch audio is coming back.
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That is exactly the issue I am having, and it is not uncommon. Again, my most recent video on cleaning methods shows me actually spraying the DeoxIT into the side of those push switches...there is an opening in the plastic switch housing. It is blocked by copper metal, but the cleaner still gets in there. You can see the cleaner fill the switch housing. Then "exercise" the switch (latch and unlatch rapidly maybe 100 times). That should help.

Also the EQ knobs cause sound to become louder, less louder in an abnormal way.
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Dirty EQ GAIN pots...check out this thread as there are some thoughts and instructions regarding cleaning the pots...haven't put the ideas to test, but most of the methods are based on tried and true practices that I've picked up from many. https://homerecording.com/bbs/showthread.php?t=27285

This weekend I will dissmantel it (including removing the cards) and start with undusting the pots,faders and switches with compressed air spray.
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I would recommend not blowing dust off the pots with compressed air...you will risk blowing dust into the shaft housing or through holes in the body of the pot. I use glass cleaner and a terry rag to wipe dust off.

Didn't realised it was so epensive back then. I thought is was a budget model these days (very strong build though). I paid 400 Euros for it which is about 460$. Not bad then. I can also buy a MSR-16 from the same guy mint condition 200 hours for 300 euros. But I think 1/2 " 16 track is to less tapewidth for the channel amount. I think I will try to buy a Revox PR series stereo recorder which are supposed to be very good.
Click to expand...

Though any mixer from the 80's needs TLC and maintenance to get it back into good condition, the Tascam mixers were an absolute bargain back in the day, and IMHO are even more so today. Hard to find a true inline recording mixer today, and they are expensive. Tascam products of that era were very well built with good manufacturing standards, innovative ideas. Reliable performers. The M-520 is a great mixer, and you can also look at the M-200 and 300 series mixers the same way. A good condition M-200 mixer, though seemingly limited in features in its day has more features than just about anything in its channel class in the "low-end" market, and probably sounds better too (in good condition).

Tijs, I'd be snapping up that MSR16 in a hurry if it were me, and tracking straight to that and than master to the DAW. The M-520 was designed to interface with a 16-track deck.
 
sweetbeats said:
No need...see the BALANCE AMP section on the back of the mixer behind the master section? That is a separate 8 unbalanced signals in on RCA jacks that go to the 8 balanced out jacks on XLR's. Changes any -10dBv line level source to +4 or +8 dBu balanced output whether the source is from an M-520 output or anything else...cool, huh? So, connect a pair of RCA cables from the OUTPUT ST MSTR A jacks to BALANCE AMP INPUT jacks 1 & 2, and then connect a pair of XLR cables from the BALANCE AMP OUTPUT jacks 1 & 2 to your monitors.
Click to expand...

wow!
didnt know about that feature!
until now i have been only using the aux 1&2.
any use of that feature when i am going into a US-122 interface-> PC?
any advantage?
or is it only good for tape machines, long cables and such.....?
thanks for tha info!
 
IMO there is no advantage and likely a disadvantage. Unless the cable runs are greater than 25' you are sending your signal through balancing circuitry that isn't needed. Rule of thumb: keep your signal as clean as possible by avoiding uneccessary circuitry/processing. Balancing the signal if your cable run is less than 25' is uneccessary...I only suggested that for Tijs because he doesn't have the right cables on hand...quick-fix to check his STEREO out jacks...
 
Two days further --> booked some results:

I went to the store and bought isopropanol spray. The store I buy my gear normally from told me this is the safest way to clean pots (no residue, pure alcohol based).

I started with the first four channels, and immediately ran into troubles:

2 fornplate screws don't have a cross profile anymore. I am not able to unscrew it. If anyone has suggestions how to remove such screws I would be glad.

Anyways I turned the module as in the Sweebeats video and sprayed the isopropanol into the pot openings and turning like a mad cow.

Dissmanteld the faders and cleaned them with alcohol (no crackles anymore). The faders are not ALPS but a far more cheaper kind.
The switches I did from the upside although not advised I have no other oppurtunity because of the screws. There are still crackles when switching but it doesn't bother me. Soloing and all that is done ITB.

Let it dry up and checked for sound: Very little crackles now on the EQ and pan. Still there are some in the Trim.

I also replaced the first to VU bulbs with Amber Leds. The result looks really nice but it is to less light to properly read and in bright lit environment the efect is nihil. So I will check out for ultrabright Amber leds.

Here is how I did it for people who want to do it as well. Unscrew the VU bar.
(only top screws and back screws). Unscrew the VU PCB and disconnect it.
In case of a 2.5 V led 20ma, solder a 330 ohm resistor at the - leg (normally the short leg). Pull the tube out the older. Solder the resistor side to the Left side of the holder and the other leg of the resistor to the right side of the holder. Et voila led powered VU's.

I also got the groups working now. Probably after the cleaning of the switches that it works now.

The noisefloor is actually quite low indeed. The noise I was hearing was... my MS-10 :). Never realised it was so noisy.

Very satisfied untill now. Can live with some minor crackles. The sound is now steady no volume fluctuations anymore.
 
One led was to subtle so I removed the resistor and added two leds (7.5 V total so this will work for a while).

The result is very satisfiing. On the image the right outer VU's are bulbs the rest leds. The leds have a warmer tone on them.

I also checked the stereo outs:works!

Everything works so far.

Still have problems with On switch off channel two. The fluctuating leds have everything to do with the switch contact because for all other switches I cleaned the leds do'nt fluctuate anymore (couldn't clean the leds itself because of the frontplate issue).

Here the result of the VU bar:
 

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Sweetbeats,

Have a 520 for several years now. Has not seen much use since I bought it about 10 years ago sadly and my basement isn't exactly the most climate controlled environment. Dusted everything off (including some mouse poop uggh!) Just cut an EP for my niece and she wants to do some more tracking. I tell you **NOTHING** sounds like analog.... (in this case 520 with Tascam 38...)

Needless to say, things like eq and switches have gotten scratchy and finicky over time. I did a little bit of research on this and found some chemical lubricant (which I think somedoby used and destroyed the slider caps on my ARP)

But then I noticed a recommendation against using compressed air? I don't have the time presently to take the board apart, and OK I'm looking for a quick fix. Any recommendations? I can actually live with the scratchy eq as it is something I'm going to set and leave alone and not ride, However, the bus assign swithes sometimes cut in and out. Have glanced through this thread, although admit not thoroughly.

Thanks
 
I wouldn't use compressed air...IMHO you're only risking forcing "stuff" down into the pots...the knob shafts are obviously where the greatest amount of "stuff" collects...the stuff that causes, in part, trouble. An air-duster is likely to get more of it into the pot. I'll know more about how my latest ideas abount effective pot cleaning worked...I've got two channels swapped out with cards that have been totally gone through cleaning-wise...pots, switches, contacts, LED sockets, etc. Plus a partial recap and opamp swap...details here

Anyway, I'll likely know more tomorrow.

Also can't say I'm comfortable with alcohol spray as there are lubricants inside the pots as well as in the shaft housing...seems as though it worked for Tijs, but I like DeoxIT Faderlube...

BTW, Tijs, nice job getting your M-520 going...LED's look nice. Thanks for puttin up the details. ;)
 
Wow...been awhile since I posted to this thread...

I'm prepping the M-520 for sale and I want everything to work and work well so I'm finally finishing up going through every pot/switch/fader and cleaning/exercising and cleaning all connectors and LED tails. I also recapped the PSU this past weekend. WOW! Finally turned it on today and listened with headphones...8 of the channels are out of the frame right now being cleaned but I routed 8 of the remaining 12 channels each to one of the 8 PGM groups (and mind you these are channels that have not been cleaned...my past experience is that all the pots and switches are noisy, and switches are sometimes intermittent), pushed the channel faders to 0, pushed the PGM faders to 0, sourced the PGM groups via MONitor channels 1 ~ 8, turned the LEVEL knobs up to 3:00 on those monitor channels, selected the MONitor section in the MONITOR SELECT switchrack, pushed the STEREO A MASTER fader up to 0 and put the headphones on...could barely hear any noise/hiss...I was shocked...total transformation. Then I thought "hmm...now let's see what happens when I turn up the headphone level knob" and to my shock it was already at 3:00!! :eek: I guess it was time recap the PSU huh? Previously it would have sounded like a waterfall in the headphones at those settings. I thought maybe something was dead so I routed the talkback mic to the SLATE and turned it up and audio is passing just fine, but the clicks and pops when turning channels on and off or PGM assignments and such is vastly reduced, simply from a PSU recap that took less than an hour to do.

Cool. :cool:

With the cleaning I'm doing on the channel strips this mixer should soon operate as good as it looks! :D
 
12 channel strips all cleaned up now, working on #'s 13 ~ 16 now. 1 ~ 12 have tested out pretty good. The MIC TRIM knob for #4 must have some wackity-fuzz in it or something. Really had to hose that down with DeoxIT and shoestring it like crazy but it is working good now. I'm finding that the areas that seem to need more work and attention than others are the MIC TRIM pots, the eq mid-band frequency sweep pot (induces nasty internal feedback when swept quickly at high gain settings prior to cleaning and not always resolved afterwards...typically seems to need additional working after the cleaning). Also, even after cleaning and exercising the slector switch are still a little fuzzy sometimes but it just takes a couple flicks and then its okay as opposed to being unresolvable prior to cleaning. I suspect that if I did more exercising on everything as I'm cleaning it might be better at the testing stage.

But so far everything is working great and all those little irritating problems are going away as I clean. No more flickering LED's either. :D
 
I don't know yet. Kinda grappling with that. Need to refill the financial hole left by other purchases so I gotta try and get as much as I can for it, but I want to get it moved too. I see them going for $200 ~ $400+ on eBay and I don't know if the condition is comparable or if they've been "gone through". So, just "thinking" out loud...mine has the custom cover, original manual, PSU recapped, everything functional, minty, and I'm planning on throwing in a spare channel card and some other parts like a few knob caps...that sort of thing...I'll probably put it up on craigslist for $595 or something for awhile and see if I get any bites. Maybe will, maybe won't, but its worth a try. You guys know what I paid for it so it almost feels criminal. :o That's on the rich side for sure, though I put my Tascam 48 up for more than I figured I should (but less than was advised) especially in this economy...marked it down after a couple weeks but I'm drawing a little interest at $690. Next step will be to sweeten the deal with some spare parts that didn't go on eBay...or the ultimate package deal!!! MINTY 48 AND M-520 COMBO $1195!!! YEAHHHHH!!! we'll see... :o:rolleyes:
 
So, at those prices, your labor and technical expertise were worth close to, what, maybe $2/ hr??

Ok....just kidding. We all know its a labor of love/ cool hobby/ etc. Someone is going to get very lucky to have these two fine machines, in almost better than new condition. It would kill me to do the kind of fine work you do and then end up selling.......


And forrtunately for me, I do not live close enough to you to be tempted to BUY!:D
 
heehee...thanks techno. I think it is actually $0.75/hr. so I could still make a killing in Viet Nam or Indonesia.

Yes, hobby, and one that I really-really enjoy. Can you tell?

I do have a hard time letting go of stuff, but as I've said here and there recently I just have more than I can use and it is really pretty refreshing to have these two items nearly complete and ready to roll. It'll make space, ease the checking account and help me focus on right and good things. I had/am having fun cleaning them up and I've learned a ton so that factors into the equation as well.

I will deliver within a 100-mile radius of the Portland Metro Area in Oregon, and that is even flexible, so if anybody knows anybody...:D
 
monitor section

I was wondering if you could maybe help me out, sweetbeats. I just purchased an m-520 and have been going through checking it out, so far everything seems to be in fine working order, except for one thing - when I assign a track to bus 1,3,5,7, etc. basically, any left bus, I won't get anything out of the channel unless I pan the monitor associated with it to the right, therefore placing the bus in the right side. Essentially it appears to me that the left side of the monitor section isn't working. I've tried a couple different things, but I can only get signal on the right side of that section. Does that make sense? Do you have any thoughts or anything I should look for?
 
Kind of makes sense...hm...so how are you monitoring the audio? Monitor speakers hooked up the STEREO A or STEREO B? Headphones?

Let's start there...
 
I have monitors connected to stereo control room out A and B. two sets of monitors, it does the same thing through both sets.

I've not done any recording yet, so everything I've listened to has been through the stereo tape return A coming from my DAW.

I did check channels. When I solo a microphone I can pan it left and right, but if it's not solo'd and it's just routed through the busses no dice, only right channel.
 
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Route a mic to PGM groups 1 ~ 8, raise the faders and then check at the PGM out jacks on the back. Hook a pair of monitors up to PGM OUT 1 & 2, the 3 & 4 on up to 7 & 8. That will tell you if it is a PGM BUSS issue, or something else since those jacks source straight off the PGM group faders. Let's rule that out first.

Have you exercised the switches in the MONITOR SELECT switchrack?
 
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