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Soundcraft 8000 problem
Old 23rd January 2009
  #1
Here for the gear
 
🎧 10 years
Soundcraft 8000 problem

Hi.
I've got a soundcraft 8000 32/8/8/2 with three Large console PSU.
After 2 hours power on an intermittent noise appears on the master and on the auxiliaries output. All channels works very good in pfl except the aux pfl. All aux send on all channels are switched in off position. The noise appearing, increases and disappears, and come back again.It's "hum" noise. The problem is the same with all my PSU.
Another problem, the peak led on a channel ligthing without signal, on another channel it's the signal led who does the same thing.
I need some help to fix the problem, and why not for upgrade it!
Sorry for my poor langage, i'm french.
Thanks for your help.
Old 23rd January 2009
  #2
This sounds like a power supply problem. Most likely worn caps. Replace them all. Use 105 degree rated parts. Increase values of the mains caps as far as can physically fit. The 8k is a nice console. It can be made silent. Install larger low impedance 105 degree local psu bypass caps on each module. They used 47 or 220 uf, go to 470 uf FM's in the thin package to fit.

Jim Williams
Audio Upgrades
Old 23rd January 2009 | Show parent
  #3
Here for the gear
 
🎧 10 years
Thank you Jim,
I'm going to do this psu upgrade. But i don't understand why the noise disappears when i listen a channel in pfl, and why the noise is on aux pfl. I thought the problem is on the master or aux channel.
And what about the led?
Thank for your sharing knowledge.
Alex.
Old 24th January 2009 | Show parent
  #4
You could have drooping voltage rails or excessive ripple that can cause all sorts of weirdness. Rebuild the power supply as I described, replace all the local psu electrolytic bypass caps on each module, use Panasonuic FM or Nichicon HE and fit the biggest values that will fit. Usually the spacing will allow for a pair of 470 uf/25v thin case caps. If there is greater spacing, go with 1000 uf/25v FM's. If the power supply has a fan, replace it with a Whisper XL to reduce noise. Refit the foam filter on the air intake to keep the insides clean. Blow out all dust and dirt.

Then get back if problems persist.

Jim Williams
Audio Upgrades
Old 25th January 2009 | Show parent
  #5
Lives for gear
 
🎧 15 years
Hi
You could simply check that the mains in your studio is at the correct voltage and that the supplies are set for the correct voltage. It may be that the mains is set for 240 and your supply is on the low side of 230. It may also vary with the time of day, typically early evening is 'low' as everyone is using power to make their meal.
If you are worried about 'playing' with the mains you can buy plug in power meter units quite cheaply which are intended to measure power consumption but will tell you what the mains voltage is. You should check the setting of the supply units with the mains unplugged.
If this is in order then go with Jim's suggestion.
Matt S
Old 26th January 2009 | Show parent
  #6
Here for the gear
 
🎧 10 years
Hi,
Thank you for your answers.
The main in my studio is 232vac, so i switch the psu on 240vac, but the problem goes up.
It was approximately the same thing with each of my three psu. There is fewer problems with the psu switched on 220vac. But i've never control the output psu, i will do that when i will replace the caps.
So i will follow Jim's suggestion.
The most difficult for me is the identification of the psu bipass caps on each module.
I've just seen there is the schematic on the soundcraft web site. I must study it.
Thank's a lot Jim and Matt for your answers.
Alex.
Old 1st June 2009 | Show parent
  #7
Here for the gear
 
🎧 10 years
Soultion

Hello!
I had a quite similar problem... I had the noise all the time!
I found out, that the problem came over the vu-display, precicely over the 24V supply for the backlights! So I solved the problem by disconnecting the lights... In fact the I think the problem's from the PSU's 24V (purple wire)!
I hope that help's you!
I'm sorry for my bad english!
Jonas
Old 1st June 2009 | Show parent
  #8
Lives for gear
 
🎧 15 years
Hi Jonas
I am assuming that you have a 'hum' problem the same as Alex. In this case the answer is the same, fix the supply with the correct parts so that it does not hum.
ALL the DC supplies from the uinit should be 'clean' and hum free, all the time.
Matt S
Old 6th June 2009 | Show parent
  #9
Here for the gear
 
🎧 10 years
Hi,
I've rebuilt one of my psu with good capacitors, and the sound problem his now resolved. Thank's for your help! But the peak led problem persist. So i will recaping the modules like Jim suggest.
Alex.
Old 6th June 2009 | Show parent
  #10
Here for the gear
 
🎧 10 years
Hi,
I need more help for recaping my input modules. I've got a stock of 220 and 440µf 25V fm's cap's, and i want to now were i can put them, and what i have to put on the over places.
I think i've correctely identifiate the different electrolitic caps:
Coupling/decoupling C3,C4,C7,C16,C21,C30,C32,C44 All 100µf 10V
Mic input coulping C01,C02 47µf 63V
Fader cap C31 C43 2.2µf 50V
Psu filtering C39,C47 respectively 2.2µf and 220µf 50V
Peak detection C35 2.2µf 50V
Signal detection C36 2.2µf 50V
Psu bypass cap C37,C45,C46 47µf 25V
Input gain C5,C6 220µf 6.3V
If someone can correct me, i want to now.
This is the shematic that i found on the soundcraft web site. I've got some modules with different issues. ( issue 3 to issue 11)
Thank's for your help!
Alex.
Attached Thumbnails
Soundcraft 8000 problem-s8000-house-input-circuit.jpg  
Old 1st August 2009 | Show parent
  #11
Here for the gear
 
🎧 10 years
Hi,
I've recap the input module who got the signal led lighting without signal, it sounds good but the led problem persist.
I've replace C35, C36, C39 and C43 by 2.2µf 50v panasonic FC , C1 and C2 by 47µf 63v panasonic FC, C3,C4, C7, C8, C16, C21, C30, C32 and C44 by 220µf 25v panasonic FM, C5 and C6 by 220µf 6.3v by panasonic FC, C37,C45 and C46 by panasonic 470µf 25v and C47 by 220µf 50v panasonic FM.
I've plug only this input module whit the master module, aux module and groups modules.
Maybe I've cause the problem when I've tested one of my psu on 240VAC.
Do you think that the transistor who controls the LED is faulty?
Another thing, on the over input modules that have the peak led illuminate without signal, when I assign groups 1, 3, 5, 7 and the pan button, peak led turns off. Is it a resistor, or a transistor ?
I hope that you understand my poor language.
Please, i really need some help.
Thank.
Alex.

Old 1st August 2009 | Show parent
  #12
Lives for gear
 
🎧 15 years
Hi
The transistor that 'shorts' the LED to make it switch off may have failed, or the IC that gives the peak indication may be faulty.
Many of the LEDS in this module are in a 'chain' that is fed a constant current so that a 'switch' shorts out the LED to make it turn off. Some are real switches, some are transistors.
Matt S
Old 7th August 2009 | Show parent
  #13
Here for the gear
 
🎧 10 years
Hi,
Thank you for your reply Matt.
I've try to change IC1 and IC8, but the problem persist. So i will try to change TR4, TR5 and TR6. It was difficult to make measurement on the PCB, because TR4 and TR5 are near the metallic panel.
And what do you think about my capacitor mods?
Thank's again.
Alex.
Old 13th August 2009 | Show parent
  #14
Here for the gear
 
🎧 10 years
Hi,
I had finally found the problem for the peak and signal led. It was a resistor between the led and the transistor.
I resolve an over problem on input module that I've by to complete the board . The optional fader led bar are different on issue p2 and p4. When i plug the p4 the 24v psu was in short circuit. Connector are not wired in the same way, and I've got to delete track and add over track. There is track to delete behind the connector, who've got to desoldering for make the job.
I use my console this weekend for a festival, i hope that i will haven't problem.
Theres little thing that I've got to resolve, but I will do that later.
I hope that this treat can help somebody.
Thank's for all replys.
Alex.
Old 2nd July 2018
  #15
Gear Head
 
MrArtrock's Avatar
 
🎧 10 years
Bump...

Hi guys, I know this is an old thread but nonetheless relevant as I got my hands on a SC 8000 this last weekend, PSU and hum seems fine but I will do a more thorough test in a day or 2...I want to ask about the mastersection mod and how exactly to cut wires as Jim W and others mention to get the monitor via aux faders instead?

Also the optional ledbars on each of the 32 channels is it something you could find or is it overkill to install them?

Cheers fr. Sweden :-)
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