Faders no longer fading? Tascam m-3500

[AnalogApples]

Finale update: case closed. Ultimately the problem was that 7 channels had faders wired BACKWARDS. I flipped the little clip that attaches to the channel PCB from the fader and BAM the fader works as normal!

All 7 channels with trick faders now have working faders only after I flipped that connection at the PCB. So, if you’re reading this in 2034, and your faders do nothing, check there!!

Thanks for all the help friends! Have a great night and rock on!

Nick

 

[RFR]

So was that a case of unplugging them and plugging them back in backwards?

Maintenance error?

Good on figuring it all out!

 

[AnalogApples]

So was that a case of unplugging them and plugging them back in backwards?

Maintenance error?

Good on figuring it all out!

I had to unsolder the fader wires from the channel strip because I couldn’t just try flipping the clip/plug. They only go in one way. This is certainly a manufacturing error. It’s not possible to plug them in backwards.

Once I flipped the fader clip and soldered it back into the PCB, they worked. So I tried it with the remaining faulty faders and they all worked.

 

[RFR]

Someone had to have messed with it.
Hard to believe the factory messed it up and the board’s been out in the world all these years with 10 non operational faders.

 

[AnalogApples]

Someone had to have messed with it.
Hard to believe the factory messed it up and the board’s been out in the world all these years with 10 non operational faders.

I know, it’s strange. This board was used in a church before I got it. I used it for 2 years with these funny faders. I just thought my tom mics were incredibly high-gain, haha, I had them turned WAY down at the preamp because the fader would boost everything 20 dB! I guess I just set the trim-pots carefully enough that I didn’t notice the faders not doing anything.

The little one-way-only plastic plugs have different colored wires every few plugs. Unless someone harvested wire looms from another Tascam which were made wrong, then soldered them in wrong also—any tech would have to purposely mess this up. But it’s possible!

 

[RFR]

It would have to be some incompetence on the part of a repair guy.

Not Tascam. They did excellent work and those boards weren’t cheap back then. ‘If’ it was like that from the factory, it would have been returned quicker than greased lightning!

Anyway, good for sorting it out!

 

[Slouching Raymond]

, is it ok to swap wires for 2 and 3? Like, can wire 2 go in 3’s spot on the fader?

Absolutely not|
The full signal goes accross 1 and 3, then as you move the fader knob, the proportionally reduced output signal is on 2.
Looking at the label on your fader pic, pin 3 is likely to be ground, and your full signal enters on pin 1.

 

[AnalogApples]

Absolutely not|
The full signal goes accross 1 and 3, then as you move the fader knob, the proportionally reduced output signal is on 2.
Looking at the label on your fader pic, pin 3 is likely to be ground, and your full signal enters on pin 1.

This confirms why the faders were doing nothing except “off” or “20db gain.” It’s mysterious how they ended up this way. The wires are permanently installed in their plugs backwards. Everything is fine until the wires go past the metal wall into the channel area. There, some are reversed inside the plastic plug.

Check it out in this photo.

#1-#4 are wires from 4 faders. You can see the permanent odd shaped plug for each set of wires. #1 has a blue wire on top, permanently mounted in its plastic plug, red on bottom. Yet #2, and #3 have a red wire on top, and the blue is on bottom. At #5, each fader wire bundle attaches to the channel. Here, on each and every channel the wires colors match. Possible a tech forgot to reverse some of the soldered in spots? At the hand unplug spot , those colors were definitely either reversed at the factory or it’s the wrong wire sets, maybe NOS. Hmm

 

[sweetbeats]

FYI the console is unbalanced signal internally. Signal is unbalanced coming into and out of the fader. That’s why there are only three wires. Input, output, and ground.