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Repairing a Tascam M-2524 or M-2516 – Part 1

January 27, 2017

I have a home studio, and the center of that is a Tascam M-2524. I bought that cheaply many years ago, just when everyone was getting rid of old bulky analog mixers. You can  find them on eBay for as little as $200-$400, and considering you get 24 very nice microphone preamps for that price it’s absolutely ridiculously cheap. It has a smaller brother, the M-2516 that has 16 channels and I suspect everything I say here goes for both mixers.

My mixer got a knock in transportation, so one filter doesn’t work, and one knob is bent. In addition, one knob that should have a center detent doesn’t, and recently one of the group fader knobs fell off. I also got some more equipment, so I decided to tear the whole studio down, repair the mixer and then reorganize it. But even opening the mixer seemed complicated, and I bought a copy of the service manual, but it tells me everything about the innards of this mixer, but nothing about how to access them. So I’m documenting it on this blog, because it’s far from obvious.

You can buy somewhat shitty copies of the Tascam M-2516/2524 Service Manual online. Perhaps you can buy less shitty copies from Tascam, I forgot to ask. But the online ones are generally good enough.

Prerequisites

  • Small and medium Phillips screwdrivers
  • Small hex drivers (optional)
  • Several boxes and jars to organize things in
  • A wire cutter (for cutting zip ties)
  • A multimeter (optional, but good to have)
  • A Tascam M-2516/2524 Service Manual (optional, but good to have)
  • A good working table where you can turn the mixer upside down and have it lying there for days, possibly weeks; Ie, not the kitchen table
  • Good places to store the circuit boards while repairing, for example, cardboard boxes
  • A camera where you document how everything looks before you remove or unscrew anything
  • Tape and a pen that can write on that tape, or another way of marking circuit boards and cables

You need to know how to solder and desolder electronics, and you need the equipment to do so, including a temperature controlled soldering iron. I won’t cover how to solder electronics. You should also be reasonably handy, and very patient.

If you want to clean the mixer, doing so while it’s disassembled is not a bad idea. Then you also need mild cleaning fluid or wipes, for example, the type you use to clean computer keyboards.

but not for cuttingStep 1: Test everything

The first step is to test every single function of the mixer, to make sure that you know what works and what doesn’t. Opening this mixer up is a big process, you don’t want to discover another error just after you repaired it.

20170111_204149

The bent knob. Also notice all the dirt.

Step 2: Order replacement parts

Look up the order numbers of the things that need replacing in the service manual. If you don’t have one, the Tascam service center can probably help you identify the bits.

I tried to contact the distributor in Poland to see if they had parts but got no answer. I also contacted the main international service online but got no answer. However, the German service center, Triplex Service, did answer very promptly! They also ship to many countries in Europe, so that’s a good place to use if you are in Europe, maybe even elsewhere. While waiting for an answer from the first places I opened up the mixer to see if I could figure out more about what exact parts the broken ones were, but I could not find exact replacements anywhere, so official service companies are still your best bet.

Rumour has it that they no longer have replacement knobs at Tascam, and a few of my knobs was missing the colored cap, so I already before contacting Tascam support bought a bunch of replacement knobs on eBay, but you can check with Triplex Service first. The knobs on the M-2500 series are the same as on the M-3500 and M-1500 series so you can look for that as well.

When you open the mixer up you may find a classic problem with old electronics: Broken, bulging or leaking electrolytes. However, I went through my whole mixer and inspected every circuit board and didn’t find one, so you probably don’t need to disassemble the mixer before ordering replacements for that reason.

Step 3: Remove the front fixings

You open up these mixers from the bottom, but before you flip it over, there are things you need to do.

First take off all the knobs on any channel strip that needs repair. If any of the potentiometers in the output section needs repair I would recommend that you remove all knobs from that section. I decided to give my mixer a good cleaning while I was at it, so I took off all the knobs.

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One knobless mixer

Remove any of the nuts on the mixer channels that need repair. There are five nuts per channel, on the TRIM, EQ MID (the lower one), AUX 1, AUX 4 and PAN knobs. As with the knobs, if you need to repair the output section, it’s easier to remove all the nuts there. It’s easy to remember which ones have the nuts because you just start from the top and put a nut on every third potentiometer.

channel-strip

A channel strip with three of its five nuts. The TRIM and MID EQ nuts are removed here

Lastly, you need to remove a few screws on the input section for each channel strip you want to remove. That’s two small screws that hold the mic input in place, and one larger screw that holds the TAPE IN and D. OUT connectors in place. I didn’t take any picture of that, sorry. I’ll take one once I’ve screwed the thing together again.

These things are all that holds the channel strip onto the front of the mixer but don’t worry, they won’t just fall down, there’s something holding their backs as well.

If you want to repair or remove the input/output connector section there’s a lot of screws there as well that needs removing. This section consists of three circuit boards, going from left to right, one with the row of dual RCA connectors, one with the row of 1/4 jacks and one with rows of various bottom connectors. These circuit boards are not held in place by anything else than the screws and will drop a small bit to land on the internal power supply. You can prevent that from happening by sticking a few contacts in them before removing the screws, and the contacts will hold them in place, if you want.

outs.jpg

The output connectors (and OK, a few inputs)

That’s it for this installment. Next up: Opening the mixer up and taking out the innards.

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