S800 Support Thread

[CapRock]

Hey Everyone,
    I Just finished 4 channels of these eq's and noticed something odd I wanted to ask about.  I set all of them up for unity gain with the trimpots.  For some reason I am getting a lot of distortion in all 4 channels but only when they are in bypass.  If I flip the switch and put them in circuit and leave all the knobs at center detent, everything sounds clean and there is almost no audible volume difference.  If I then flip back to bypass the sound remains clean for about ten seconds and then slowly starts to become distorted again.  All pots, switches are working as they should and so are led's.  here is my ground scheme in case it helps define the problem.  IEC input to chassis -> Chassis to PSU ground (AC input side) -> PSU ground (DC output side) to both PCB power supply input grounds.  XLR's are grounded to the chassis tab on each connector and I left the ground pads for the XLR's on the PCB empty.  If anyone has any insight as to what may be causing this please let me know, thanks in advance...



Cap

 

[peterc]

@Caprock

If you have a look at this pic

you will see that 1 section of the bypass shorts out a resistor to ground, and if there is no ground to that pad, it might be that there is a 10sec discharge path that leads to the distortion.

Make sure that that leg of the switch is properly grounded.

Peter

 

[peterc]

@coriolis

http://twin-x.com/groupdiy/displayimage.php?pid=4694&fullsize=1

 

[CapRock]

Do I need to run the ground wire to the switch, in my case a 3pdt wired as Matta showed in his diagram, or do i need to run the ground wire to a specific solder pad where the bypass switch connects on the PCB?

 

[peterc]

If you have ground attached to the PCB, then the switch pin should automatically be grounded.

Just check to see that this pin is actually grounded

Peter

 

[CapRock]

Ok, it is grounded.  I think the issue I was having is that I was sending a signal close to digital "0" or +18db through the unit and i was distorting the input.  For some reason when I engage the circuit without any pots turned the problem goes away.  I found that around -9 DBf is where my signal begins distorting.  Anything around -18 dbf (0dbu) - -9 dbf is clean.  Does that sound about right for what the input of this circuit can handle?

 

[coriolis]

@peterc:
Thanks for the schem - but I can barely read the component values. Got anything in better resolution?
Sorry to be a pain!

C

 

[Rellister]

Peter,

Boards still available for this?
PM´d also.

Thanks

 

[peterc]

Rellister

I have PCBs,  PM sent.

Regards
Peter

 

[JayDubrek]

Hi Peter- just wondered when PCBs are being sent out?
Cheers
Jay

 

[peterc]

Jay

PCBs were sent during last week. Shipping is 2-4 weeks, usually 2-3 weeks.

So they should be showing up from next week onwards.

Regards
Peter

 

[JayDubrek]

That's great...thanks Peter!

 

[Rellister]

peterc,

are my pcb´s in the mail?
Over 4 weeks, getting worried :-\

 

[JayDubrek]

Yep-still no sign...everything okay with the PCBs Peter?
Thanks
Jay

 

[Tsane]

I received mine yesterday (Belgium), so they're probably somewhere very close now

 

[spase]

still waitin here

 

[peterc]

Hi al

Sorry for the delay, they should be there anytime soon.

A batch of boards arrived with  another client on Tuesday that was sent at the same time.

Peter

 

[Rellister]

Thanks Peter, all good.

Which cases/panels do people have in mind who still haven´t built this?

 

[kpearsall]

I'm still deciding on that too. Was making a design for an 8 channel, but I want it so exact it really has to wait until I have the actual cards ready to go so I can make measurements....

 

[JayDubrek]

Boards arrived this morning....thanks Peter!

Jay