Tascam DX-2D dbx question.. Help!!

[Molasar]

I've had a Tascam 32 along with a DX-2D sitting around for some time. The 32 works great; finally the time came to fire up the DX-2D. It did fire up, but the 2 "engaged" LEDS did not light up. No matter the position of the engaged switches, they do not light up. I placed the 32 in record mode: no dice. I disconnected the unit from the 32: same behaviour. I did not test for sound tho...

Finally I opened 'er up and didn't see anything unusual inside (no blown caps or cold solder points). DeOxit-ized the switches, then I put 'er back together again. No dice.

With the switches on the engaged position (undepressed), the LEDS glow for the tiniest instant when I switch the unit off...

The question is now mandatory: Is this normal behaviour? What's the normal behaviour, connected and/or disconnected from the 32? If there is a malfunction, from these symptoms, could it be the DX-2D itself, or the controlling circuitry from the 32?

Please help!

Thanks!

Mike

[RRuskin]

Originally Posted by Molasar

I've had a Tascam 32 along with a DX-2D sitting around for some time. The 32 works great; finally the time came to fire up the DX-2D. It did fire up, but the 2 "engaged" LEDS did not light up. No matter the position of the engaged switches, they do not light up. I placed the 32 in record mode: no dice. I disconnected the unit from the 32: same behaviour. I did not test for sound tho...

Finally I opened 'er up and didn't see anything unusual inside (no blown caps or cold solder points). DeOxit-ized the switches, then I put 'er back together again. No dice.

With the switches on the engaged position (undepressed), the LEDS glow for the tiniest instant when I switch the unit off...

The question is now mandatory: Is this normal behaviour? What's the normal behaviour, connected and/or disconnected from the 32? If there is a malfunction, from these symptoms, could it be the DX-2D itself, or the controlling circuitry from the 32?

Please help!

Thanks!

Mike

Under normal circumstances the switches should be "out" for the circuit to be engaged. I'd ignore the led's and see what happens when you put signal through it. It may still work but have an inconsequential led problem.
All of mine have been modded to be stand alone units. Find the control transistor on each channel and short one outside leg to the inside leg. The unit is now always "on"

[Molasar]

Does this mod make the DX-2D a simultaneous encoder/decoder?

[RRuskin]

Originally Posted by Molasar

Does this mod make the DX-2D a simultaneous encoder/decoder?

Yes it does.

[Molasar]

Ok... hmm... will this mod still enable the front switches to work; i.e.: so that the unit can be "bypassed" if necessary?

[RRuskin]

Originally Posted by Molasar

Ok... hmm... will this mod still enable the front switches to work; i.e.: so that the unit can be "bypassed" if necessary?

Yes. No functions are changed.

[Molasar]

Well, during weekend I opened my Tascam 32 to change the belt, clean 'er up, etc. I looked at the DX-2D control signal connector on the back of the 32; I was surprised at what I found!

There is something definitely missing here. Any clues?

Am I missing a miniPCB? Wires? If so, connected to where? Help!!

[evm1024]

nothing missing. the dx2,4 were licensed to tascam with the provision that they would not work on other decks. Tascam only. That little jumper and the control cable was the solution.

As was stated above many people put the enable jumpet in the dx and then were able to use it on anybodys deck (that used -10 dBv). They do encode and decode at the same time. The front panel switches only bypass the DBX circuit and nothing more.

Regards, Ethan

[Molasar]

I had the idea that the DX-2D was not a simultaneous encode-decode processor, and that the 32 deck, etc. would "tell" the DX-2D when to encode and when to decode, depending on the deck's mode (record, playback, etc.), though, of course, now that you say it, you wouldn't be able to record and monitor off the tape at the same time...

So basically, 4 of the 6 pins of this control signal jack are for all practical ends useless? I though I saw 6 wires coming from the control signal cable soldered to a PCB inside the DX-2D.. (have to recheck... lucky me, I took photos!)...

Has anybody turned on an unmodded DX-2D/4D without the control signal connected? Will the LEDs light up when engaged (switches toggled out)? Or is the "jumper" needed for the DX-2D to work it's magic (and light up it's LEDs)????

[RRuskin]

Originally Posted by Molasar

I had the idea that the DX-2D was not a simultaneous encode-decode processor, and that the 32 deck, etc. would "tell" the DX-2D when to encode and when to decode, depending on the deck's mode (record, playback, etc.), though, of course, now that you say it, you wouldn't be able to record and monitor off the tape at the same time...

That's the way a stock unit is supposed to work. Tascam had to arrange it that way to comply with their license with dbx Corp. However, nothing in the license said that Tascam dbx units had to be comprised of a single card switching between encode and decode so the DX-2/4/8D units had individual cards per channel for each function. The decision to do this was because of customer complaints about how much time it took the original dx-8 unit which was a single card per channel device, from 80-8 days, to switch functions, making punch in/outs too slow. (The 80-8 was slow enough. A dx-8 made it worse.)

So basically, 4 of the 6 pins of this control signal jack are for all practical ends useless? I though I saw 6 wires coming from the control signal cable soldered to a PCB inside the DX-2D.. (have to recheck... lucky me, I took photos!)...

Has anybody turned on an unmodded DX-2D/4D without the control signal connected? Will the LEDs light up when engaged (switches toggled out)? Or is the "jumper" needed for the DX-2D to work it's magic (and light up it's LEDs)????

Can't help you on these. All of my units were modded after purchase so control cables were never used.

[mastercontrolme]

Hmmm, that pic does not look stock to me. I had a 34B that IIRC had a board connected to that socket with a few components on it. I guess the best solution is to figure how to make the DBX stay "on" all the time.

[evm1024]

OK scratch what I said RE looks OK. I'm not sure about the dx2 (I'll chack my 32 manual later tonight) but you may want to look at this thread for a discription of how the dx4 works.

http://homerecording.com/bbs/showthr...highlight=dx4d

Some of the pins are for expansion (2 dx2 on a 4 track machine or 2 dx4 on an 8 track machine for example)

The internal jumper overrides the 1.0 Hz signal and lets it work everywhere.

I have a 32 on the bench at home as well so I'll look inside it as well.

Regards, Ethan

OK looking at the dx2/4 schematic (now I'm remembering) which are the same. Control cable pin 1 is gnd, pin 3 is +5 and pin 2 is 1.0 Hz. Pins 4,5,6 are just passed through to the next unit so that you can cascade them.

[Molasar]

Ethan,

Did you have a look at your 32?

[evm1024]

Yes, and No.

I touched it and was called away before I had the back off. I'll see about it tonight.

However, we do know that the jumpered connection will not work. That the DX2 needs a 1hz square wave (or perhaps a 2.5v signal) to activate a stock DX2/4. And we know that the jumper installed per the other thread puts the DX2/4 into active mode (no cable required)

So the question is: Do you want to make your 32 "stock" or do you want to use the DX2.

Regards, Ethan

[Molasar]

Gee... that's a tough question...

First of all, the DX-2D is and will be permanently mated to the 32, so I guess, seeing things this way, it would work either way. I don't know if my DX-2D is modded, but I don't think so, or the channels LEDs would turn on (unless they are toast).

Second, I just saw a 34 backplate on ePray and thought about getting it just for the dbx connector. There seems to be a small PCB attached to it and a lead.

I don't know where this lead should end up... if your 32 is stock, then you could point me in the right direction...

I could then get this dbx connector from the 34, swap it on my 32, solder or connect the lead to where it goes, and I should get a working DX-2D...

On the other hand, I could just mod DX-2D and get it working, saving a few bucks...

That my 32 is not stock and was tampered with brings tears from my eyes...

I don't know if the 34's dbx connector is identical to a 32s, so I'm just guessing here...

I'll stay tuned for any enlightening thoughts...

[Molasar]

Hmmm... Anyone?

[Molasar]

Well, I finally got the DX-2D connector from ePay and well, this one definitely looks "complete"...

Now the problem is I can't figure out where that lead plugs into.... any ideas?