Toft Audio ATB 04m trouble

[Sinkia]

Hi folks !

I getting a problem with my toft audio ATB 04m…

Here is what is wrong with my desk :

Gain :

Nothing happen when I crank the gain knob between 1 and 90%, and at 90%, it's like passing a "step", like a "jump" of gain.

Pan :
Pan L : no problem
Pan R : the more you pan at right, the less there is sound.. It's like disappearing when it's hard right pan..

It do the same thing on the 4 channel.. I'm having the idea it might come from a psu problem, but I'm not really into desk problem..

Any ideas guys?

thanks in advances !

best

 

[radardoug]

Cheap Chines pots! Doh!

 

[abbey road d enfer]

Hi folks !

I getting a problem with my toft audio ATB 04m…

Here is what is wrong with my desk :

Gain :

Nothing happen when I crank the gain knob between 1 and 90%, and at 90%, it's like passing a "step", like a "jump" of gain.

Pan :
Pan L : no problem
Pan R : the more you pan at right, the less there is sound.. It's like disappearing when it's hard right pan..

It do the same thing on the 4 channel.. I'm having the idea it might come from a psu problem

It's a possibility, maybe one of the rails down (check for burnt protection resistors), but I think the signal, when "passing the step", should be quite distorted. What does PFL say?

 

[Sinkia]

It's a possibility, maybe one of the rails down (check for burnt protection resistors), but I think the signal, when "passing the step", should be quite distorted. What does PFL say?

PFL are all right, no distortions

but the gain are clipping really easily.

I have read somewhere in the web that you can it hard the gain gnob witouht clipping, it would "distort/compress" in a musical way..

Here no.

you have maybe 30 db of gain course, and it clip not in a musical way at all !

It's a possibility, maybe one of the rails down (check for burnt protection resistors),
[/quote]

I'm gonna check on the PSU to have a look on  it..  I didn't event thought to any blow fuse or resistor..

 

[pucho812]

Lets take it from the top...

What version rev is this?

Can you measure the output of the power supply? The psu outputs around +/-17VDC  and +48VDC. YOu can easily measure the PSU output without the mixer connected. Use the end of the multipin cable, the female side before going into the console.  Very easy to measure the voltages in reference to ground.  IF the PSU has a fault none of the channels will work at all.  I have all the board schems But I cannot give them out without legal issues, nor would I ever want to do that to a company without permission which I would never be able to get.

If it is a rev 1, then you most likely have broken pots or dead chips.  They are not mechanically braced and are pretty crappy to begin with.  They break very easily... The chips are all JRC, for some reason those JRC chips like to fail more so then others. I recomend replacing their tl072 with TI tlo72's 

If it's post rev 1, like rev 2 and up to the current rev 3, then you have less likely the possibility that your pots are damaged as they changed pots at rev 2 to a mechanically braced  pot that is less likely to break although that can happen.

For your gain issues,  Asumming the pot is not broken, I would suspect a fault in the preamp chip. Depending on date of manufacture  for the desk it will either be an ina 217 or a that 1510. They are basically the same and either will work when you replace it.  It will be IC 1 on the PCB.

As for the pan you either have a broken pan pot or dead tl072's. That is the big thing that can go wrong in that circuit...
Pan pot is vr10 and feeds IC 6 on both sides which is the mix amp buffer.

Assembly on this is a big pain to get all this stuff out.  Proceed with caution and do not force anything as you can damge stuff if you force it.

 

[Sinkia]

Lets take it from the top...

What version rev is this?

Can you measure the output of the power supply? The psu outputs around +/-17VDC  and +48VDC. YOu can easily measure the PSU output without the mixer connected. Use the end of the multipin cable, the female side before going into the console.  Very easy to measure the voltages in reference to ground.  IF the PSU has a fault none of the channels will work at all.  I have all the board schems But I cannot give them out without legal issues, nor would I ever want to do that to a company without permission which I would never be able to get.

If it is a rev 1, then you most likely have broken pots or dead chips.  They are not mechanically braced and are pretty crappy to begin with.  They break very easily... The chips are all JRC, for some reason those JRC chips like to fail more so then others. I recomend replacing their tl072 with TI tlo72's 

If it's post rev 1, like rev 2 and up to the current rev 3, then you have less likely the possibility that your pots are damaged as they changed pots at rev 2 to a mechanically braced  pot that is less likely to break although that can happen.

For your gain issues,  Asumming the pot is not broken, I would suspect a fault in the preamp chip. Depending on date of manufacture  for the desk it will either be an ina 217 or a that 1510. They are basically the same and either will work when you replace it.  It will be IC 1 on the PCB.

As for the pan you either have a broken pan pot or dead tl072's. That is the big thing that can go wrong in that circuit...
Pan pot is vr10 and feeds IC 6 on both sides which is the mix amp buffer.

Assembly on this is a big pain to get all this stuff out.  Proceed with caution and do not force anything as you can damge stuff if you force it.

Wao many thanks pucho!

I won't be able to go to the studio before beginning of next week!

I Will plan to go there on monday, and have a close look on all the part you are Pointing at!

I guess my partner should have all the doc from it.

This is the rev 3...

I have been looking over the internet to check if some other people had the same issues, but I didn't find anyone having it!

I'll let you Know as soon as I get the mesurement!

Thanks for your help!
Cheers

 

[kambo]

how does the actual working units sounds tho ?

 

[Sinkia]

how does the actual working units sounds tho ?

Eqs are great! Really musicals.

Pres : I can't really give you my point of vue because mines have an issue.

I would say, if you're doing rock/pop rock and harder, it is a great piece of gear, but you can't really have it as a all purpose mixing board.

As far as I for mine fixed I would give you a real answer (from my point of view of course!)