Ward beck aux send

[snellular5]

Hey folks! I have been working on a small ward beck console. I have now solved all issues except for one channel who’s aux send doesn’t function properly. I replaced the aux in/out switch and the pre/post switch yet I still don’t get proper signal. Now at normal levels there is no aux send but if I crank the gain on the preamp until it red lights I can get a healthy signal out of the aux. I’m a bit stumped as I have checked continuity between it and a healthy module and can’t seem to find anything wrong. Any help would be appreciated as I’m losing my will to finish this project hahah. I can include pictures of the schematics if that would help.

Cheers and thanks in advance.

Matt

 

[snellular5]

Schematics of the aux section. I figure the signal must be fine up to here as if I select cue the signal gets to the cue bus just fine.

 

[ruffrecords]

Looks like is uses balanced signals. Maybe one or both the 2K4 resistors is faulty.

Cheers

Ian

 

[snellular5]

Thanks for the reply Ian!

Yes it does have balanced signals throughout. I test both of those 2K4 resistors and both seem to meter out fine.

 

[ruffrecords]

Thanks for the reply Ian!

Yes it does have balanced signals throughout. I test both of those 2K4 resistors and both seem to meter out fine.

Have you checked the bus feed resistors (47K)?

Cheers

ian

 

[ruffrecords]

Does this happen an all channels or just one?

Cheers

Ian

 

[snellular5]

I will go and check that right now.

This only happens on this one modules.

 

[snellular5]

Both bus feed resistors tested normal

 

[snellular5]

To anyone who wanted to know what happened. I shorted the 5k pot and it passed signal very nicely. I guess the pot is bad or the wiring. Will look into it

 

[pucho812]

To anyone who wanted to know what happened. I shorted the 5k pot and it passed signal very nicely. I guess the pot is bad or the wiring. Will look into it

cool. I tried to respond to this earlier but diy crashed.  could I have caused that? maybe. But I was going to suggest trying another module in that position to see if it was mating connector for the module, bent pin or not mating properly. Then if that worked it would have shown the slot is o.k. it's uncommon but it can happen.  From there I would have suggested checking the pots as you already did the resistors. while it is uncommon the pot could be broken.  turns out you already did that and found a bad pot.  8)

 

[snellular5]

Thanks Pucho! It was you who crashed it!! I was trying to see if there were any responses and couldn't get through!

So after some tinkering tonight I found something weird. The pot that is there only works when I add a wire and ground one of the pins of the pot to the chassis. Once this is done Im still 6db down. Do you all think this is still the pot? Im not too sure how easy it is to find a replacement for this seemingly custom allen and bradley 5k pot. Im sure I could find something else to fit there though.

 

[snellular5]

I also realise that grounding that pin on the pot is what is causing the 6db dropped leg effect. Im wondering why the pot doesnt work without this extra wire to ground. On all other modules there is no grounding on the 5k aux pot.

 

[pucho812]

can easily be a broken pot.  on the toft mixers the pots of that where they visibly look o.k. but they are cracked and not working

 

[snellular5]

So the pot i need to replace is a 5k pot with 3 terminals. I have the exact same series pot but with 6 terminals and 2.5k resistance. Would it be possible to use this stereo 2.5k pot to make a 5k pot by routing the signal through the "left" side and then into the "right" side? The reason I ask is this pot would fit perfectly into the module.

 

[pucho812]

So the pot i need to replace is a 5k pot with 3 terminals. I have the exact same series pot but with 6 terminals and 2.5k resistance. Would it be possible to use this stereo 2.5k pot to make a 5k pot by routing the signal through the "left" side and then into the "right" side? The reason I ask is this pot would fit perfectly into the module.

resistors in series add. so technically you could however I don't know if that is the best solution here.
Have you tried testing the pot. I know if you ground it you get signal @ 6dB down but have you measures the resistance of just the pot itself to confirm it's o.k. and nothing else is a foot?

 

[abbey road d enfer]

So after some tinkering tonight I found something weird. The pot that is there only works when I add a wire and ground one of the pins of the pot to the chassis. Once this is done Im still 6db down. Do you all think this is still the pot? I

Think! -6dB means only half the signal is fed. This is probably not the pot; it's the feed from one side that is missing. Since it happens on both sends, it eliminates the pre/post switch. Check the signal at C44/45 and the equivalent pre signals (can't see where they come from on the pic).
Does the problem occur in both pre and post positions? If it does that would suggest the Pre/Post switch is the culprit.