DBX DX-8 for use with TEAC 80-8.

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samth3mancgp

samth3mancgp

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I purchased one of these recently hoping for the best, but there appears to still be some problems with it.

When I got it no audio seemed to pass through it. I heard a tiny bit of something when I cranked the gain on the mixer and the headphone output. I took it apart and took all of the cards out and used contact cleaner on all of the switches and the leads for the card as well as the sockets. I put it them back in and I have not tested for audio yet but there are still many LEDs that will not light up. This helped me with my other analog purchases so it was just standard procedure.

I fixed the power LED because I saw that there was a loose soler joint on it. There are things that look like switches encased in plastic that say Omron on them. are these relays? Should they be cleaned too, maybe that's the reason that NONE of the red LEDs for encode light up? I couldnt imagine that ALL of them are burnt out, because more than half of the green ones do come on.

Any help would be greatly appreciated. :) Here is a link to a site where the schematic for it can be found for free http://www.audioschematics.com/tascam.html
 
Do you have the control cable hooked up to a Teac 80-8?
 
theres a port on the back that says "remote" but I was unaware that that was a control cable like the DX-4D. Is that for a control cable? I dont see the port for it on the 80-8
 
Is the "remote" port on the back of the DX-8 the one that "unlocks" it like the control cable does for the DX-4D? maybe there is a similar quick mod available for it?
 
Can anybody help me with this? I cant get any signal to go in or out of my DX-8.


DSC_3577.jpg


Is this "remote" port supposed to hook up to the 80-8?

DSC_3571.jpg


I have it lightly taken apart right now.

DSC_3572.jpg


Some of the caps I can see..

DSC_3573.jpg


I have already cleaned out the switches on the cards and the contacts for the slots. could it be the relays? they all seem to "click" and i can see tem move when i hit the switch. I get basically zero audio through it. I'd like to get this unit working :confused:
 
I would say that the 'remote' connector is almost certainly for a remote control panel, and has nothing to do with the DBX.
 
That's a relief, because I do not have a cable for that and the 80-8 does not have that type of connector. The problem of no audio getting through the unit still remains though which is not good :eek: Maybe somebody here has worked on one of these before or has experience with one?

Can relays be "cleaned" and put back into proper working order the same way as pots and switches? Though I am not sure if that may be a problem.
 
http://www.audioschematics.com/tascam.html

...I don't know whether you've already done this, but you might want to download the 80-8 service manual here, as it has the instructions for connecting the machines together. (Don't forget that the rar-file is passworded)

Apparently there's a little backplate on the 80-8 which has to be removed, exposing some weird RJ45-looking connector. This would be the switching connector, and it probably won't work without that being hooked up.
 
Yes, there is a cable assembly that goes from that wierd RJ-45 looking jack to the octal socket on the DX-8. You have to have the cable.

There is probably a mod to get the DX-8 to operate without the control signals that come over that cable from the 80-8 like there is with the DX-4D but I don't know what it is.
 
Ahh and there is the answer to my questions Dang I'm not sure whether to be relieved or to be discouraged by this though haha. I don't know where I am going to get a cable like that but then again, I guess it's good to know the unit isn't completely fried

Do you think that "evm1024" or may be able to find out how to mod it?
Maybe the DX-4D and the DX-8 are similar enough that similar parts/circuits are used?

thanks for the help thus far
 
samth3mancgp said:
Do you think that "evm1024" or may be able to find out how to mod it?
Maybe the DX-4D and the DX-8 are similar enough that similar parts/circuits are used?
Click to expand...

The DX-4D seems to have one circuit board, the DX-8 seems to be based on cards and a backplane. You won't be able to apply the mod directly, but with the schematics in that download, someone with better electronics-fu than me should be able to figure it out.
 
sweetbeats said:
Yes, there is a cable assembly that goes from that wierd RJ-45 looking jack to the octal socket on the DX-8. You have to have the cable.

There is probably a mod to get the DX-8 to operate without the control signals that come over that cable from the 80-8 like there is with the DX-4D but I don't know what it is.
Click to expand...

Perhaps I could just rig up this thing with stripped spare wires in each of the jacks so it can get the control signal? That would probably work fine. My analog setup is not going to be moving anywhere anytime soon. Then I can test it/use it that way until I can find a cable or one of the electronics gurus around here can figure out a mod. The problem is that I took the little metal plate off of the back of my 80-8 and there is no jack there..? Maybe its somewhere else? If you are looking at the back of one it is on the right side? I can get some pictures up for you guys if you want.

EDIT: I found where that remote connector is on the 80-8 its behind one of the larger metal backplates. What I still need to find is a schematic for how to wire up the remote connector. Then I could rig it up using just some spare cables for now.
 
jpmorris said:
The DX-4D seems to have one circuit board, the DX-8 seems to be based on cards and a backplane. You won't be able to apply the mod directly, but with the schematics in that download, someone with better electronics-fu than me should be able to figure it out.
Click to expand...

The DX4D is a simultaneous encode/decode unit. One would assume that there is a card for each function - 2 cards per channel.
The DX8 switches between encode & decode depending on what the control signal tells it and has one card per channel.

It is possible to stall a dx8 into one mode or the other which would necessitate having 2 of them - 1 for encode and another for decode. I knew an engineer with such a rig but I don't know what mods were done.
 
RRuskin said:
The DX4D is a simultaneous encode/decode unit. One would assume that there is a card for each function - 2 cards per channel.
Click to expand...
That got me curious, so I opened one up. The bulk of the unit is a single board, which replicates the same pair of circuits four times, as one would expect.
Intriguingly, the PCB is split down the middle with a series of perforations, so I imagine that they used the same board split into halves to make a pair of DX2Ds.
Doesn't really help the original poster, but kind of interesting.
 
I am having trouble locating the place on the 80-8 where the DBX control cable is hooked up. I don't see anything like it when I open up the backplate on the 80-8.

I have a paper copy of the service manual and owners manual for the 80-8 and I cant find the place it shows the connector being located
 
Is it possible that only later revs of the 80-8 had the DBX port? If so, you could have a problem.
 
samth3mancgp said:
I am having trouble locating the place on the 80-8 where the DBX control cable is hooked up. I don't see anything like it when I open up the backplate on the 80-8.

I have a paper copy of the service manual and owners manual for the 80-8 and I cant find the place it shows the connector being located
Click to expand...

I had one of the first 80-8's in Minnesota. Going from MEMORY, not pictures, there is a cover plate (about 1" high and 2" wide) on the back of the machine that unscrews and reveals the receptical for plugging the cable in that goes between the machine and DBX unit. I have a picture of it around here somewhere, but it could be nearly anyplace. If I find some time I'll dig around.
 
i just looked at mine. if you look straight at the back of it. the cables for the dbx unit are to the right of the input\output jacks.
i haven't yet taken off the cover but the cables are there
let me know if you need more info.
 
I just took a closer look at the inside of the unit. It appears that there is a "male" socket for a small PCB or attachment that may have gone to the DX-8!

the problem now is that the small receptacle for the control cable is missing and not attached to this PCB socket? I don't know if you guys have read through the whole thread but I am missing this control cable entirely. My plan was to sort of emulate the control cable using a bunch of spare wire unless I could find a cable for it.

I'm doing google searches for the cable but it's looking grim because this thread shows up as one of the top results no matter what I search... like I'm the first person to ever be looking for one online! :eek:
 
I don't think you'll find one of these cables easily. It's a pretty weird cable. I bought a parts deck yesterday and there was a dx8 included, so I had a quick look at it.

I can remember the connector on the main pcb is wired directly to the function select buttons, so if you arm a channel/amp, there also goes a voltage or signal to the corresponding channel on the dbx-connector. Hope this helps.

cheers

Joeri
 
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