Correct cable pinout for Telefunken/TAB w395a

[Nightmusic]

Hello everyone,

After checking everywhere on the web, I’m still having some difficulties finding correct cable pinout for my Telefunken/TAB W395a german equalizer.
To be more precise, I do have schematics which clearly show the original pinout, but since the connector fitted at the back of my unit is not original (the previous owner probably recabled his own way with a different kind of connector), i have no reference regarding correct pinout with the original connector anymore (which original connector i finally found on ebay though)
So before putting original connector back in place and going into adventurous path with resoldering, i thought i could rely on the cable colours as a proper reference, in case of course someone could help me retagging each one of them, according to the original connector pinout order.(Besides red and blue cables which obviously speak for themselves, that’s actually only 5 cables left to identify)

So i attach here a pic showing the actual cabling between the pcb and the non original connector of my unit, so if anyone could spy a bit into his own unit just to check which cable color correspond to which (original) connector number, that would be just awesome!
I guess, just knowing which pin number corresponds to which color would be more than enough for me, since i already have the original connector pinout, so i could then draw my own conclusion about each cable function.

I hope i did it clear enough with my explanations…anyway, thank you very much by advance, dear DIYusers!

 

[gyraf]

from original schematic you should be able to figure out the needed external connections, then trace from those parts of the circuit to the cables attached..

If you post a schematic and/or layout, it's probably easier to help

/Jakob E.

 

[Nightmusic]

Hello Jakob,

Thank you very much for your help.
So i tried to do what you suggested, i traced connections on the pcb from the schematics indications (see files attached) and the only clue i could get was for the green, black and white wires: since they seem to be connected to a track marked ‘a-b-c’ on the pcb, and that an ‘a-b-c’ mark is also available on the schematics (close to what is named ‘EÜ 3079’ block), i concluded they should be connected to the inputs transformer of the modules.
So i concluded that the other 2 yellow cables would stand for the outputs instead, even though i couldnt trace them point to point (But these 2 yellow cables go inside the transformer which is located on the left of the module pics).
Before I would plug it to power, would you be able to confirm this conclusion makes sense? Particularly, is the transformer on the left of the picture (the one close to the 1000uf golden capacitor) -which to me looks like a power transormer- is supposed to also handle the outputs, at same time as the 24v? (I marked that transformer on the edited pic, and also on page 2 of schematics)

Thanks a lot!!

 

[gyraf]

!! hold your horses - if it is a power transformer, it does not belong in there, and must have been added later. And I'm not at all sure you'd ever want to have a power transformer and 220VAC that close to your inductors and audio transformers, it's asking for trouble&hum. So it's probably your output trafo (it also looks like it was there from birth).

Input: Find the two wires going to the input transformer. You'll have significantly less than 10KOhms between these if you ohm/beep them. Don't worry about +and-, reconstruct this later
Output: Find the two wires coming from the output transformer. You'll have significantly less than 100Ohms between these if you ohm/beep them. Don't worry about +and-, reconstruct this later
Power +24V: this connects to the cathode of the BAY18 power diode
Power Ground: catch this at the minus end of the 200uF capacitors in the power supply section

/Jakob E.

 

[Nightmusic]

Hello Jakob,
Thank you for these quick and clear infos!

Indeed you are right-It can't be a power transformer since its perfectly connected to original pcb without apparent mods on it, so it's certainly the output transformer instead.

So, based on my later assumptions (black/white wire= Input, Yellow wires= Output), I found:

Input: 12-13 ohms between two yellow wires (of course the DVM beeps)
Output: 300ohms between black and white wire,
-So it sound like correct input/output-?
Power +24V: checked as suggested, it's ok
Power ground: checked as suggested, it's ok

Is such a low impedance between the two outputs wires supposed to be normal?
Also, any tip how to reconstruct the hot and cold points of each inputs/outputs afterwards?

Thank you Jakob !

 

[gyraf]

output is probably the 12-13 Ohms, and input the 300 Ohms - and these look right

To reconstruct absolute polarity, clip a sinewave with a diode so it's assymmetrical, and observe input/output of unit on a scope

alternatively mix the processed signal with unprocessed, if it gets louder you're in-phase - if you get less, you're out of phase..

/Jakob E.

 

[Nightmusic]

Great that you confirm that it's all good!
So I modified the picture to clarify all this, here attached.
Will try to reconstruct polarity the way you suggest, i understand the most important is not to be out of phase anyway, whatever the method used so it should be an easy fix.
Just taking the opportunity of getting you in the discussion...and by pure technical curiosity, could you please tell me what are according to you, these 2 other metal boxes next to the input transformer? (I traced them as being 'D3083' and 'D3081'on the schematics).
Thanks!

 

[gyraf]

Those are eq inductors, multitapped niceones..