Tascam M-320 is noisy after it warms up

[Micha]

That's what my friend ended up telling me as well, about the power caps, that it's just glue. But I will have him replace them, and you're saying that as long as they are the same voltage I can go up 50% in value. He has actually told me the same exact thing about Japanese parts that are used in all the newer Macintosh gear and how it's notoriously shotty work. I greatly appreciate all the help, I really love this mixer. I can get a great sound from the pre's. I'm excited to hopefully bring it back to fully functioning. I'll keep posting as we go.

 

[SkywaveTDR]

Good for you, Keep up the work on it and the unit will return back to new. I have had people tell me the pres as they call them are no good in mixers. I guess this is all a bunch of guess work. I have never had any trouble with them. People listen to gossip all the time and draw conclusion from that. It is all ridiculous as they don't have the facts and listen to just anyone. There is nothing wrong with these preamps. I don't use the word pres too much as that signifies a sense of lack of knowledge to me kind of like the people that over use awesome and call you dude.

 

[Micha]

Well I sat down with my friend and we sent a sine wave through each channel and he checked at several points in the signal path and we determined that the circuit boards that go across the bottom just needed to be re-seated. They must have gotten a little loose over the years, either way we unhooked them all checked the solder joints and sprayed some deoxit and now all my program busses are working properly! I'm glad it was such an easy fix. I do have another question that I'm not sure if you would be able to help me with. I'm using my aux sends for headphone mixes, when I send a signal out of any of the aux sends I am only getting one channel in my headphones. I plugged my headphones directly into aux send 1 2 3 and 4, and I can't understand why I am only getting a signal in one channel of my headphones. I checked the manual and it doesn't specify if the 1/4" aux send jacks are TRS or TS, I don't think using a 1/4" TRS in a 1/4" TS jack would cause me to only hear one channe right? Any idea what might be causing this? Thanks!

 

[SkywaveTDR]

Well making some progress as I suggested. The Aux outs I think are unbalanced single outputs. TRS does not automatically mean a stereo output. TRS means a balanced out that has hot of tip and cold on ring and this in headphones would be out of phase 180*. This is not to be used for that purpose unless you used two channels that one Aux would be L and the other R channel.

The Stereo out of the unit is more correctly used for headphone feeds. This is a stereo output. When questions arise the study of the block diagram will tell anyone who has understanding how signals are routed in the unit.
Under Maintenance the 1-2 and 1-3 pages are of importance.

If the mixer itself can not develop the headphone mixes you want that is why the Model 1 mixer was made for. It is 8 to 2 mixer.

 

[wkrbee]

Good story Sky.I had a guy repairing repeaters-phone-and his way to repair was replacing components-starting with R1

 

[Filopu04]

Hello there , so I also purchased an old M-320 and this post really helped me to get it on it's feet again . I resoldered all the pots and buttons and all the pin connectors on the sum board bu I still have some issues .
Two tracks are still quiet (12 and 17) but they are not really dead because when i crank up the input gain to full the OL diode lights up and i can hear it really far away so it's not the preamp but something after that ...
And the First channel of buss 2 won't work either in tape return mode or in buss mode .
Does anyone know where i should look for a broken solder joint or anything like that ?
And also it's getting pretty hot around the power supply unit , is it normal ?

 

[SkywaveTDR]

When buss lines do not work then it is time to look at the back of the mixer for missing or tarnished accessory loop jumpers. Not all mixers have them but this might be one. get the block diagram out and start to trace the path. If you put a line in and can not hear it at the direct out then there is something wrong with the connection. When busses stop working it can be in the master section where they go into op amps and that would be serviced by a technician with a scope. Sometimes there are no easy answers and the Technician has to get involved.

 

[Filopu04]

ok thanks for the fast answer , i repaired the two tracks (bad solder again) but yeah the buss doesn't want to work even with new solder everywhere ... It does not have jumpers , all is controlled by a button to select tape return or stereo buss (all the leds are lighting but no sound) i think the problem comes from the buss PCB because when i touch the contacts on the SUM PCB i can hear left and right so i guess the master is ok but the signal never arrives to the SUM PCB . but i'm gonna try the direct out thing you told me .
Thanks again !

 

[Giselle Chacon]

Hi everyone! An old thread, I know, but it seems quite relevant to my situation. I have an M-320B I inherited that started in the family and came back, but saw some rough times in between. It was also stored uncovered in dusty conditions for about 10 years. That said, it actually 'sounds' really nice! The EQs are surprisingly sweet at all settings and more versatile than I expected from a 3 band. And though I'm working around a whole lot of bad jacks and (I'm suspecting) loose bus cards, what's working sounds very nice and clean. Not digital sterling. Remember clean? Of course in here you all do. So I learned a lot on the thread, my replacement jacks and meter bulbs are here, and I'm going to try and fix a wonky left main buss, suspect master inserts, several bad channel inputs, diagnose and fix a non-functional desk light system, fix the non-functional effects send, and re-seat all the buss cards and connectors. Thanks to this thread my last few questions have been answered. I'll post again with my results!

 

[Giselle Chacon]

Just a quick follow-up after getting into my M-320B today- OMG those VU meters are a pain to get the covers off of. I did figure out a trick* eventually. I replaced every broken jack plus both master inserts. I tried to replace the Effects send jack, but it's a two conductor jack so I just cleaned it. The buss cards were all very tight, but I know corrosion can build up in between contacts after a long time in storage, so I carefully inched them up a bit and worked them back down a couple of times end to end, then rocked them to seat them fully. A bunch of the RCA jacks in the master section are cracked, but they don't seem to be affecting the BAL outs so I left them alone. I don't plan to be using any RCA connections. LED meter bulbs seem to be working good, but I wish I'd turned the LEDs towards the meter faces- they're a bit dim. I couldn't get to the BNC to fix the desk lamp fixture- the power transformer is in the way and after 10 years without having to do any repairs, I discovered my multi-meter is dead. Next time in.

Outcome? No more buss issues. FX send working. Left and Right masters clean with no signal issues. The whole board sounds better and cleaner. I have VU meters! Got my XLR-Bal 1/4" snake and installed it which got rid of the impedance/level mismatch going into the +10dBu line inputs. Much better signal through the balanced inputs. I gotta be honest folks, somebody commented about "noisy mixers" back in the thread but after purposely adding digital noise to recordings for 10 years, it's nice just to hear it through an analog board. I just sounds... warmer.

*VU meter cover trick- Remove top and bottom bezel screws on the meters (you'll have to go inside and loosen the screws that hold the meter bridge to the chassis first). Once you get the meter bridge loose, it should rotate to allow access to the VU meters. The clear covers are taped to the meters on both sides and at the top, but the metal mounting plate makes it hard to get at the tape. If your mixer is original like mine was, the tech wrapped clear tape from the bottom of the meter up the side and onto the top of the meter cover. Cut it there, 1/4" from the edge and grab the edge of the tape, pulling it out and down to release the meter cover from the base. I used a razor knife to cut it free once it was clear. This way you can release both meter sides and carefully tilt the cover up to peel off the tape at the top. If you're using radial LEDs like I did, make sure to turn the LEDs towards the face or the light may be dim. Don't worry about polarity on the radial LEDs apparently they can go either way. Enjoy your new meter lights!

 

[-mjk-]

Thank you for the very detailed write up. Welcome to the Tascam Forums!