S800 Support Thread

[Siegfried Meier]

Calibrate the EQ - I've noticed every trimpot comes standard turned up too high, so you need to perform this.  And read this entire thread, because we've already discussed this.

Sig

 

[stitch-o]

its a good thing 'I apologize in advance'...
starting thread study now.



cheers and thanks!

:::in calibrating the eqs for unity gain, i have discovered the trimpots work but I am loosing a great deal of signal.
I've set the trim at the highest possible level before distortion but I'm loosing a huge amount of signal.
I'll start there but could it be possible that the pot pins are shorting on the metal mounting?
I had used electrical tape and flush cutters as per Matta's suggestion but maybe tape got rubbed away?
That will be a last resort check I guess...

thanks all...

 

[matta]

Stitch, can you upload bigger pics of your wiring? I think you may have a loop which can cause all weird stuff, also can you confirm that you have the correct pins going from the Moulex to the XLRS? Also uplaod some pcis of the PCB's and I'll give them the once over.

This should be an easy fix and we will get through ti together  ;D

Cheers

Matt

 

[stitch-o]

You kats are a prince... ;D
It very well (most probably) could be something quite obvious and stupid on my part.
I second opinion is always very valuable.

Stitch's S800 pic 1
]Stitch's S800 pic 2
Stitch's S800 pic 3
Stitch's S800 pic 4
Stitch's S800 pic 5
Stitch's S800 pic 6

Cheers!

 

[matta]

Well fixing that ground loop would be the first place to start....

Right now you have a ground referenced in multiple places, follow a star ground scheme.

It seems like you have a quazi scheme already, but you need to LIFT the Grounds on your PCB XLR ins and outs. Right now you have a loop because the PSU ground is tied to the chassis and the PCB's AND your star ground.

I would also put from heatsinks on those regulators.

Also I need a BIGGER pics of the PCB to check for faults there.

I assume the distortion/loss of signal happens on BOTH channels?

Cheers

Matt

 

[stitch-o]

oops. yes, you are correct about connecting the PCB shields.
Fixed that.

What sort of heatsinks would fit on that configuration?
and, yes, the LOW signal/distortion is on both channels.

I'll try and take some better pics in a bit.
+ I know what you are looking for on the PCB as far as shorts, I'm going over it again myself right now...
Could I have put a wrong value part in somewhere possibly?
Cheers and thanks Matt!

 

[matta]

oops. yes, you are correct about connecting the PCB shields.
Fixed that.

What sort of heatsinks would fit on that configuration?
and, yes, the LOW signal/distortion is on both channels.

I'll try and take some better pics in a bit.
+ I know what you are looking for on the PCB as far as shorts, I'm going over it again myself right now...
Could I have put a wrong value part in somewhere possibly?
Cheers and thanks Matt!

Well short are a good place to start, I was thinking more about the wrong value/component, so need to see a BIGGER pic to make out the bands.

Cheers

Matt

 

[stitch-o]

Is it normal to run across 'bad' resistors?
I powered down and disconnected my S800 and measured resistor values across both boards, here are the ones that stuck out at me:::
place board value channel 1 channel 2
r45 10k 6.92k 6.94k
r8 1.2k 1.163k 1.166k
r9 1.2k 1.163k 1.162k
r13 1.5k 1.437k 1.437k
r24 2.7k 2.28k 2.29k
r25 4.5k 3.47k 3.46k
r44 1.5k 1.371k 1.37k
r20 2.7k 2.29k 2.28k
r21 4.7k 3.47k 3.46k
r28 47k 10.2k 10.2k
r30 47k 15.5k 23.3k
r31 47k 15.5k 23.3k
r15 1.2k 1.154k 1.153k
r45 10k 6.94k 6.91k
r46 47k 10.5k 10.4k
r17 10k 6.92k 6.95k
r12 1.2k 1.152k 1.152k
r10 1.2k 1.153k 1.152k
r11 4.7k 4.06k 4.07k


anyone have any suggestions?

Cheers again!!

 

[matta]

Is it normal to run across 'bad' resistors?
I powered down and disconnected my S800 and measured resistor values across both boards, here are the ones that stuck out at me:::
place board value channel 1 channel 2
r45 10k 6.92k 6.94k
r8 1.2k 1.163k 1.166k
r9 1.2k 1.163k 1.162k
r13 1.5k 1.437k 1.437k
r24 2.7k 2.28k 2.29k
r25 4.5k 3.47k 3.46k
r44 1.5k 1.371k 1.37k
r20 2.7k 2.29k 2.28k
r21 4.7k 3.47k 3.46k
r28 47k 10.2k 10.2k
r30 47k 15.5k 23.3k
r31 47k 15.5k 23.3k
r15 1.2k 1.154k 1.153k
r45 10k 6.94k 6.91k
r46 47k 10.5k 10.4k
r17 10k 6.92k 6.95k
r12 1.2k 1.152k 1.152k
r10 1.2k 1.153k 1.152k
r11 4.7k 4.06k 4.07k


anyone have any suggestions?

Cheers again!!

Stitch,

You CANNOT measure across a resistor in circuit, power or no power... in order to measure correctly you would need to lift the leg of one end of the resistor.

I highly doubt that the kits from Colin would differ, I have built over 16 channels with the parts form Colin and have not had  single issue.

I'm pretty sure that there is prob a placement issue we need to resolve, hence my suggestion for a BIG ASS pic of the board to look over for ya  ;D

Cheers

Matt

 

[stitch-o]

Is it normal to run across 'bad' resistors?
I powered down and disconnected my S800 and measured resistor values across both boards, here are the ones that stuck out at me:::
place board value channel 1 channel 2
r45 10k 6.92k 6.94k
r8 1.2k 1.163k 1.166k
r9 1.2k 1.163k 1.162k
r13 1.5k 1.437k 1.437k
r24 2.7k 2.28k 2.29k
r25 4.5k 3.47k 3.46k
r44 1.5k 1.371k 1.37k
r20 2.7k 2.29k 2.28k
r21 4.7k 3.47k 3.46k
r28 47k 10.2k 10.2k
r30 47k 15.5k 23.3k
r31 47k 15.5k 23.3k
r15 1.2k 1.154k 1.153k
r45 10k 6.94k 6.91k
r46 47k 10.5k 10.4k
r17 10k 6.92k 6.95k
r12 1.2k 1.152k 1.152k
r10 1.2k 1.153k 1.152k
r11 4.7k 4.06k 4.07k


anyone have any suggestions?

Cheers again!!

Stitch,

You CANNOT measure across a resistor in circuit, power or no power... in order to measure correctly you would need to lift the leg of one end of the resistor.

I highly doubt that the kits from Colin would differ, I have built over 16 channels with the parts form Colin and have not had  single issue.

I'm pretty sure that there is prob a placement issue we need to resolve, hence my suggestion for a BIG ASS pic of the board to look over for ya  ;D

Cheers

Matt

ahhh and now I know and also show my inexperience...
check your PMs and cheers!

 

[3nity]

do both channels act the same?
Try measuring voltages at critical points from board to board...

Jorge Aristondo.

 

[matta]

Stitch,

I looked over the pics in you PM'd me, all seems fine comparing my PCB's against yours... which makes me think of wiring. If you PSU connected to the star ground? Hard to work out your grounding scheme from the pics.

Can you draw up a sketch and post a pic?

Cheers

Matt

 

[stitch-o]

heh...uh. :
so, there is this little jumper right next to the 3rd TLO71.
It would seem that if you miss installing the jumper, the eqs loose a lot of signal and become distorted.

heh...well, live and learn.

Many many thanks Matt and others responding, having second opinions helped exercise the troubleshooting...


This this thing sounds wicked! Cheers and thanks again...

 

[matta]

Hah Hah,

THAT will do it! Glad you found the problem.

Cheers

Matt

 

[substitute]

I noticed R25 is marked 4k5 on the PCB, I'm using Colin's kits which came with no such value.  But it seems like I have an extra, 4k7 will this work out?

 

[matta]

I noticed R25 is marked 4k5 on the PCB, I'm using Colin's kits which came with no such value.  But it seems like I have an extra, 4k7 will this work out?

Substitute, substitute (sorry I had to) it for 4K7 all will be well  ;D

Cheers

Matt

 

[Brolik]

I didn't find a final conclusion on the best way to put in the styrene caps that came in colins kits.  They definitely measure more accurate in one direction than the other, and I saw that it was "better" to put the foil side (with the line) on the ground side or on the opamp output, but can't figure it.  Could someone with better schematic reading skills give me a hint?  I saw that stitch's had the lines on the square pads, how's it sound?  Could this have anything to do with the freq responses that are coming up slightly different than spec'd? Thanks in advance for your help.

 

[substitute]

Cheers Matta!

 

[substitute]

Does anyone have a part#, preferably, Mouser, for the Green PSU Bridge rectifier.  I mistakenly ended up with a small IC that won't fit on the board.

Thanks!

 

[Brolik]

Substitute, I used 583-BR64 for the rectifier with success.  A little overrated, but the best fit for the board I could find.

Any help on the direction of the polystyrene cap placement, or is it too stupid a question to warrant an answer?

~Matt