Tascam M-216 repairs (pots and PCBs, oh my)

S

Sonarcade

Member
I have a mixer that has gunked up and noisy pots and a defective right channel. I had opened up the bottom to reveal that the pcb (if that's what it's called) for the right channel slider snapped in two. I'm not so sure how this would affect the output of the channel, but I suspect that it does. One of the other main screwy things about this mixer is that it has a pot with a lot of play on the "vertical" axis (i.e. pushing and pulling, not twisting along the axis of rotation) -- so much play that I have to push it down to get a signal in my headphones.

I figure that at this point, the pot's going to need replacing. The thing is, I've never worked with installing pots and was wondering if the pot in the picture below is fairly standard and available at Radio Shack. Also, would the pcb need replacing or will some kind of conductive glue fixed the problem? Thanks.



 
So your M-216 suffered some trauma at some point...:(...BUT, it now has an owner that wants to right past transgressions. ;)

Go sonar...go sonar...go, go, go sonar...

Are you able to see the side of the body of the malfunctioning pot? And this is for the headphone level? There will be some letters and numbers on the side of the pot...maybe something like 10KAX2 or something similar. If you can, check out what's printed on it and post back (or if somebody has the parts lists for the M-200 series?)

That PCB...yikes. You can't really just glue it together and hope that it works...ideally it needs to be glued back together with a good epoxy, and then every solder trace that crosses that crack needs to be jumpered (i.e. you have to scrape the green stuff off to expose the copper on both sides of the crack for each trace and then solder a little wire bridge to the exposed sections of copper on both sides of the crack. Kind of a pain, but it can be done.

Can you get a closeup of the trace side of that busted PCB?

You could also get the part number off of that PCB (it'll be on one side or the other), call Tascam and see if they still carry it...they might. Somewhere on the forum awhile back somebody had a reel deck with a cracked control PCB...all the logic circuits and stuff...pretty hairy to repair. The guy opted to buy a new PCB (naked...no components on it) for 50 bucks. Maybe that sounds steep, but in his case it was going to save a ton of time and likely prove more reliable in the long run with a critical card like that.

Anybody have a parts M-200 mixer out there??
 
Those Tascam mixers look way too complicated for me!!!! No valves inside!!!!

Building or modding a small tube guitar amp is about my limit!!!

Been looking for a schematic for the Tascam Midiizer MTS-1000 to see if I can get it working properly but no luck on the net.
 
Hi Cory. thanks for the encouragement -- coming from one of the premier DIYers in here, that's kinda awesome. =) I'll be back with more pics but just wanted to poke my head into say that I did call Teac/Tascam and got quoted $12 a piece for both the PCB (or rather the entire fader unit for the R channel) and the rotary pot. With tax and shipping added in, I'm looking at around $30, it seems. But again, I'm in no rush to get either of these parts going since I'm mainly using the mixer for its pre's and seamless setup with my 38.

But still, I'm kind of puzzled as to what a busted fader has to do with the entire channel being rendered inaudible. Although I'm not super familiar with the way the signal's carried, the VUs for bus 2, if I recall correctly, doesn't respond either. Could it be that the fader was set to a low to muted level before it got busted and it just got "stuck" at that level (if that makes sense)?

anyhow, once i rig up my camera, I'll take pics. It's a tad hard to identify a "trace" side of the fader PCB, since both sides are the same color (tannish orange), unlike some of the other PCBs where one side's green and the other tannish orange. Another note about the pot (which I might as well buy from Teac considering the price? or is that too steep as well?)= (= because colon key's busted) I found a sticker that gave me a few numbers and googled it to no avail. It's an Alps part as are apparently the rest of the components in this mixer. I'll provide numbers in a bit with the pictures. Thanks again.

tracedental = maybe once I get the rest of these issues sorted out, I'll have to enlist your help when taking up a tube amp as my next project. That sounds pretty friggn awesome. Anyone say Orange?
 
Hi Cory. thanks for the encouragement -- coming from one of the premier DIYers in here, that's kinda awesome. =)
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Haha! Wow...thanks for the compliment, but seriously, just because I post a lot and talk alot doesn't mean I know a lot! I do know enough to be dangerous for sure...dunno if that makes me premier or not. You're doing the same as me...open it up, observe, ask lots questions, learn, fix, enjoy. ;)

Hey, are the faders on the 216 long or short throw (60mm or 100mm)? I'm thinking they are short throw, but if they are long throw I have one of those faders. PM me your address and I'll send it to you.

I have been looking at the pictures on my phone and just now looked at them on a full-size screen :o...I understand now. You don't actually have a busted board, but the fader is busted as well as the pot...you said that but I got confused...my guess is that something got dropped on the mixer at one point and the master fader and headphone pot took the brunt of it.

Did you ever get the numbers off of that pot? Same thing...if I have one I'll send it to you.

But still, I'm kind of puzzled as to what a busted fader has to do with the entire channel being rendered inaudible. Although I'm not super familiar with the way the signal's carried, the VUs for bus 2, if I recall correctly, doesn't respond either. Could it be that the fader was set to a low to muted level before it got busted and it just got "stuck" at that level (if that makes sense)?
Click to expand...

The whole signal goes through that fader. That fader is ka-busted. Can't tell which terminal is hanging on that busted piece, but its got nowhere to go...the circuit is incomplete so that's why you have nothing to the master out jacks, nothing to meters, nothing...it would go to the headphone pot since that is upstream of the fader, but that's busted too. Does that make sense?
 
Cory - I don't know, man. Don't think I haven't seen your tech vids floating around this forum. That's some heavy forensics right there.

I can't tell firsthand what the faders' lengths are, but from a related post, I found that the fader is a 60mm fader. The code "5KD" is stamped on it as well as "635D" and the fader's by Alps.

As for the pots, I found the numbers on two stickers on two adjoining pots =
"645H 10KA"
"637U 20KA"

also by Alps.

I get everything you're saying about the fader and I think the concept of the entire signal going through the fader is new to me, seeing as how I'm used to the common disclaimer about midi controllers not affecting nor generating an audio signal itself. That's cool that the signal isn't routed independently of the fader -- well, save for the fact that now my right channel's busted. =)
 
I would spring for the new fader and pot. I've brought faders back to life, but only if they're not broken apart. Is the pot moving up and down on the inside, or might you have loose solder joints?

I've owned an M-216 and M-208 for years and have been all over them with mods and fixes. IMO, they’re fairly easy to work on compared to other things I've worked on.

:)
 
+1 to what Beck said. I don't have the short throw fader. Still though, if you can get the numbers off of the pot I'll check to see if I have a spare. I need the numbers off of that pot and not just the adjacent pots.

You might be feeling like you didn't get the deal you thought, but I still think you made out pretty good, and $12 for a fader on a long since discontinued piece of gear ain't half bad. ;)
 
firstly, I apologize for the delayed response. I've been without net access for awhile and am back online.

I did manage to get the Tascam part numbers for the fader and rotary knob as follows =

-5282411000
-5284010100

I had one concern before I start getting out the soldering iron. Are there any precautionary measures I should take to ensure that I don't overheat or fry the pcb or is it relatively hard to really cause any damage to these cards (or any other non-wire part for that matter)?

Thanks again for the offer and hopefully I can start being more active in this community again. I love this place!
 
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I've been using a soldering iron for a couple decades, but just here and there, non-critical stuff. Since joining this forum in April I've gotten into doing stuff on PCB's and I had some troubles. Here's what I've learned about soldering from the kind folks here:

  • Make sure you have a good tip on your iron
  • keep the tip clean as you work (i.e. have a wet piece of sponge or lint-free cloth at your work station, and wipe the burned gunk off the tip often)
  • Use a solder bulb or vacuum pump solder sucker when removing components. It really helps to get as much of the solder off of the pad to get that component out, especially with pots and switches.
  • If you are removing components from a PCB, especially the kind like the boards found in the M-200 series (and 300 and 500 sereis too...many others as well), you want to be pretty quick about your work. Too much heat for too long will disturb the trace and solder pad's adhesive that sticks it to the board...then the pad or trace lifts off. Its not the end of the world. Lots of ways to work around that if it happens, but it is nice if you don't have to mucky with it.
  • Once the solder is sucked, chances are that the tails of the component are still gonna be tacked to the pad in some way...resist the urge to just rock the thing out or pull it out. That increases the chances of the pad getting damaged. Put the tip of your iron on one tail to heat it a little to break that tack and pull that side of the component a little, then the other side, then back to the first side etc. until its out. You can also trim the tails off with a good pair of flush cutters once the solder is sucked of...that speeds things up. May favs are when the component literally drops off the board after the solder gets sucked off. :)
  • Once you have removed the component, clean the pad. I use cotton swabs and iso alcohol.

Any spare boards in anything you could practice on? That advice was given to me and I didn't heed it. Didn't do any irreparable damage to anything, but it is a bit nerve-wracking. :o

Would it help if I put up a video or something? I'm no expert for sure...crazy hobbyist is a pretty good title, but I'm getting the hang of it and you could learn from my mistakes. It really sounds a lot more complicated than it is...but the steps above have really helped the quality of my soldering work on PCB's...I'd done lots of cables, but when I got into PCB's it required some additional steps.

BTW, I checked the part numbers you put up and cross-referenced with the M-500 series and the part numbers do not match. Tascam did have specific part numbers by model even for common parts (i.e. the same pot could be used for multiple models, but they'd have a different part number for each one anyway even though it was the same part), which is why having the numbers off the pot would help.
 
As far as getting rid of old solder, I've been using a braid. I think I may have already caused irreparable damage to my soldering pencil tip, just by neglecting to tin it in my first couple uses and letting it just heat up. It's now really discolored and doesn't respond to solder too well. I would find that, for example the solder would react instantly to the rarely used parts along the shaft of the iron, while it would take awhile to get going on the tip itself. So it looks like a new tip is in store for me.

Also, would you say that there's a certain time limit you'd give a soldering tip before you turn in the towel? I was at one point, holding the pencil in place for about 25 min.s with a few slips here and there. My guess is that this isn't normal.

to return from the topic of soldering in general to the tascam m216 itself, I found that bus 2 doesn't seem to respond, VU and all. I suspect this may be a bad card as a cursory glance revealed that the connections that would need to be set are indeed set. But just in case, is there anything else I should look for? Thanks.
 
Braid sucks IMO. Get a bulb type solder sucker or better yet one of the automatic solder vacuum pumps...

I use a pencil iron by Antex...M12...evm1024's recommendation and I am very happy with it. I use the 2NC chisel tips. When you are doing PC solder work in particular the protective coating on the trace side of the PCB's gets things all gunked up...clean your tip often as you work with a piece of wet t-shirt or a sponge. I bet your tip isn't damaged, but coked up. Scrape the black buildup off with a razor blade or something. Also, I have learned from evm1024 that the little 2NC tips on my Antex iron can just be filed to renew the tip. Any soldering iron tip will erode as you work. So, keep it clean, reshape the tip as needed and tin it when you are done filing.

Also, when you have removed a component, clean the solder pad with a swab and some iso alcohol to get rid of the scorched yucky stuff...it will make the new solder joint take really well especially if your tip is clean.

Don't know what to tell you on your aux buss issue. I forget: do you have the manual with schematics and stuff? Are you getting any audio or is it just the VU not working?
 
I ended up getting a new solder tip and was able to now know the difference between a working tip and a non-working tip and discovered the importance of tinning the tip prior to working. Most of the coking that you speak of seems to have occurred through my use of a wet rag to periodically clean it. The rag would burn and somehow would also leaves blemishes on the tip that looks like oxidation or something. I also filed away at some of the old tips so that I can reuse those as well. Thanks for all the pointers. I will get a proper solder sucker eventually.

I also don't have the schematics but have been referring to cjacek's scan of the m-30 manual periodically. The audio is completely gone from buss 2 as far as I can tell. But truth be told, I have been having a lot of trouble finding out how the sound is routed and which buttons not to press (PFL, tape) when monitoring. I have a vague idea as to how it works now, but it's definitely a more complicated process than working with my Mackie 1202-vlz--that's for sure.
 
I took apart the broken fader to see why the "break" would've disrupted the signal flow. I found a strip of something that seems to connect the top "lead" with the bottom "lead." I was wondering if anyone here may be able to shed some light on what this strip consists of and if it's worth salvaging as an extra fader in case one of my other ones go.

dsc02555ot5.jpg


Although barely visible, the fissure is enclosed in the red rectangle. Thanks.
 
Tats am m-208

Beck said:
I would spring for the new fader and pot. I've brought faders back to life, but only if they're not broken apart. Is the pot moving up and down on the inside, or might you have loose solder joints?

I've owned an M-216 and M-208 for years and have been all over them with mods and fixes. IMO, they’re fairly easy to work on compared to other things I've worked on.

:)
Click to expand...

I'm hoping you get this! I have two tascam m series mixers. A m-208 and an m-216. On the M-208 you have to hold down the monitor volume pot to hear it. Then it works. I tried to spray some Deoxit in there...no luck.

On the M-216....the same volume pot does not work at all.

I tried to pull that group of parts out the back and I've got it listened but so many wires to cut...manage etc!

Any tips? I'd ship these for repair if I knew where!

Thanks
 
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