Teac 80-8 And Dx-8 Diy Control Cable

[samth3mancgp]

Hi I am new to this Forum.  This forum was recommended to me by a user on another forum.  I have a TEAC 80-8 and a DX-8 dbx type 1 noise reduction for it.  These two pieces hook up via a control cable so all switching between encode mode and decode mode are done by the tape machine when you switch between input monitor, sync mode and reproduce mode.  Having this control cable keeps one from having a switch 8 channels on the dbx unit between encode and decode mode so often while recording.  My problem is that I do not have this control cable that hooks up to do the job for switching. 

Here is a link to a site where the schematic for it can be found for free http://www.audioschematics.com/tascam.html

Here are some pictures of it taken apart

I have it lightly taken apart right now.

Some of the caps I can see..

I have improvised the one side of the control cable that hooks up to the machine.  here are some pictures. 

Soldered CAT 5 cable

You see some of the contacts are not used and hang off of the side of the actual PCB.  but all of the others line up just right.  It fits nice and snug on the board.

Since the CAT 5 only has 8 conductors I had to use a second one for the last 4 cables and I marker it with blue cable to let me know which set it was.  Now..  I think I am going to buy one of those 11 pin circular connectors and hook the other end of my crazy cable to one of those, but for now I would like to test and get used to using the DBX using just the stripped end of the cables stuck into their respective sockets.  Anybody think they can help me figure out which cable goes where?   I have the hard copy of the service manual and owners manual for the 80-8 and I have an electronic copy of the DX-8 manual  If anybody needs to see something.

I have improvised the one side of the control cable that hooks up to the machine.  here are some pictures. 

Soldered CAT 5 cable

You see some of the contacts are not used and hang off of the side of the actual PCB.  but all of the others line up just right.  It fits nice and snug on the board.

Since the CAT 5 only has 8 conductors I had to use a second one for the last 4 cables and I marker it with blue cable to let me know which set it was.  Now..  I think I am going to buy one of those 11 pin circular connectors and hook the other end of my crazy cable to one of those, but for now I would like to test and get used to using the DBX using just the stripped end of the cables stuck into their respective sockets.  Anybody think they can help me figure out which cable goes where?   I have the hard copy of the service manual and owners manual for the 80-8 and I have an electronic copy of the DX-8 manual  If anybody needs to see something.

Here are some schematic things that look helpful..

This is what is shown for the connector on the 80-8 PCB.  Do you think the numbering pattern on this  (D1, DB, D2, DC etc) indicates which is the top and bottom contacts for the socket?  I think If I can have this confirmed I may be able to finish hooking this up.

This is what I found on the DX-8 schematics PDF.  The manuals do not label these connections the same way.  I would assume 1-8 should match up?  numbers 10 and 11 on the DBX schematic match up with DA and DF (RMS in and RMS out on the 80-8 schematic?  At least from what I have gathered or guessed at..  the 9th connector is the only one in question, because 12 on the DBX one is just a ground and isnt part of that cabling.

I'm totally lost at this point.  any help would be greatly appreciated.

 

[abbey road d enfer]

You have to understand that the Ready 1-8 lines control the status of cards 1-8. That means that Ready 1 goes to card 1, Reday 2 to card 2 and so on. They shoud go more or less directly to Pin 4 on dbx cards. Ther is a connector on the backplane that takes these eight lines and distributes them to the individual cards.
Unfortunately I couldn't open the schematics, but you should find it easily, since it's a multiway connector that doesn't go to a card.

 

[Emperor-TK]

On a related note, I have a box of 80-8 parts I've been meaning to do something with, input cards, headstacks, mechanical, etc.  Do you need any spares?  I'd be happy to let them go in one lot for a good-guy price.

-Chris

 

[samth3mancgp]

I think I like this place already!  I just took the backplate off of the DX-8 and found on the PCB where the cards plug in a label that says "remote"  the wire soldered to ch 1 is brown and I found a brown connector on the remote port.  All of the rest follow suit with that.  I think I may have just had where pin 1 is on the remote port mixed up.  I am going to try and wire it up that way.  Now what do the last three connectors go to?  what exactly are they doing if 1-8 go to the channels?

I may be interested in those extra parts    I really love the sound of the 80-8.  I don't see myself ever getting rid of it even if i get a machine with a higher track count.  There will always be a place for its ballsy analog sound (Boston anyone?) in my recordings of myself and of other people.

EDIT:  OK I started to wire it up a bit just the first 8 channels the way you said.  There is a sign of life!  channel 1 was switching between encode and decode via the sync/playback switch on the 80-8!  also.. when I held the channel 1 control connector to ANY of the other 8 channels those ones worked too.  Why wont the control signals from the other ones work?  I checked the voltage across each of the 8 channels with my DMM and only channel 1 is getting anything.  It is a constant .2V.  None of the others read anything.  I looked at where the signal coming from the first conductor was going and it isn't the same as the rest of them.  By looking at the schematic for the 80-8 I can't tell exactly which cable is which.  ???

 

[samth3mancgp]

Ok I have tried to follow where some of the connections are going on the PCB.  The one that seems to "unlock" each channel does not go to the same place as many of the others.  This one that was getting the constant .2 V strayed away from the others. 

Most of the other contacts (which I have come to believe are the ones that are "ready 1-8" on the schematic) go to the record arming or record "ready" switches for each channel.  I think all of those ones are getting a constant .10 V.  There are two others that get a constant .15 V  I think. 

I also checked to see if these voltages change when change between sync mode and reproduce mode.  They do.  I can provide pictures for all of these things that I am trying to describe here if somebody needs them. 

I think what it comes down to now is knowing which cable goes where!  This is going to mean figuring out where the "Ready 1-8" are on the 80-8 PCB connector and where they go into the DBX remote port  ???

If somebody that has this machine with dbx could match up which color cables are on each contact for the PCB socket connector (left-right/top-bottom) and how they link up to the dbx unit It would probably be the easiest way for me  :-[  Maybe have some pictures with it?    I'm not a very educated DIYer haha.

 

[samth3mancgp]

Anybody?  This is the only place I have gotten any insight on this DIY yet! 

 

[trancedental]

You also might be able to get some help & information on the www.homerecording.com look in the analog forum where there are posters that know about Tascam / Teac tape machines

 

[samth3mancgp]

I'm already registered at HomeRecording forum and I also started a topic there  :'(  that was actually the first place that I posted it.  This is where I have gotten the most help so far so I may try posting there again and waiting for help here too.