Soundcraft Series Two "Dead" - Repair Advice

[edwood83]

Hi everyone-

I have a Soundcraft 200BVE 24 channel mixer that has "suddenly" died. I use the term suddenly loosely because I haven't used the mixer in four months and the first time I turned it on, it didn't work. I moved apartments but was pretty gentle moving the thing. I don't think I damaged anything but of course you never know. Each of the four meters shows a steady level. NO onboard LEDs work. See this following video for the issue:

Soundcraft 200BVE Mixer Problem - YouTube

The power supply is separate and shows +/-7.5V, 12V, and 24V lit. +/- 17 are not lit. According to the manual the 17V rails supply power to the audio. I am wondering if anyone has any repair suggestions.

I have not had time to get into the unit yet so I haven't checked anything, however, I know I am not going to get to it for at least a week so I am looking for insight, or maybe even a repair manual, if anyone has one. I know these PS units are nearly impossible to find ant any logical price point so I am going to fix it myself. I haven't had to do anything to this mixer in the past so I'm not very familiar with it.

Anyone ever had a similar failure? Ideas of what to check internally?

Thanks,

-Ed

 

[ecc83]

This..
Soundcraft 200BVE Mixer - Overview. - YouTube
Gives a good overview of the mixer and shows the PSU to be a pretty chunky linear, 50Hz jobbie, should be easily fixable.

But my first port of call would be that cable. Looks like DINs and if so probably the 240dgr indexed "B" DIN? I can't see but is there a connector on the PSU? If so check for the 17V rails there.

If no volts at output you almost certainly have a regulator gone down. Because the rails are 17 volts not 18, this is a Douglas Self design IMO and will have a crossfeed system to shut down both supplies in the event of one failing.

http://www.prostudioconnection.net/0113/CPS150_Schematic.gif
Dave.

 

[edwood83]

Thanks for the great info. I really appreciate it. I'll post back when I get into the unit next week.

This..
Soundcraft 200BVE Mixer - Overview. - YouTube
Gives a good overview of the mixer and shows the PSU to be a pretty chunky linear, 50Hz jobbie, should be easily fixable.

But my first port of call would be that cable. Looks like DINs and if so probably the 240dgr indexed "B" DIN? I can't see but is there a connector on the PSU? If so check for the 17V rails there.

If no volts at output you almost certainly have a regulator gone down. Because the rails are 17 volts not 18, this is a Douglas Self design IMO and will have a crossfeed system to shut down both supplies in the event of one failing.

http://www.prostudioconnection.net/0113/CPS150_Schematic.gif
Dave.

 

[edwood83]

So the regulators were fine. The issue was a 10000uf capacitor that has gone bad, though not visibly. I found the exact schematic online, for the CPS 450 power supply. I'm posting it here for other people's reference. I put a temporary cap in (450uf @ 35V) to test and both LED's came back on.

I have some replacement capacitors on the way. While I'm in here I am going to replace all the caps on the board since they are all old and I have no idea what maintenance was done to the unit. I'll post back to verify that this fixed the issue.

 

[ecc83]

Super! Glad you are sorted.
I notice the preset pots on that schematic, are they decent quality sealed types? If so fine, if not I would replace them with sealed ones. In fact, because they cost very little more I would fit multiturn cermets.

Dave

 

[edwood83]

Super! Glad you are sorted.
I notice the preset pots on that schematic, are they decent quality sealed types? If so fine, if not I would replace them with sealed ones. In fact, because they cost very little more I would fit multiturn cermets.

Dave

The pots on this board are only for adjusting the voltage output, so they should be fine as is.

The unit is back in action- I replaced all caps. For anyone else who runs into a similar situation, just replace them while you're in there. I think I spent about $40 on parts. Not so bad to feel confident I won't be killing another old cap soon and have to do it all over again.

 

[ecc83]

The pots on this board are only for adjusting the voltage output, so they should be fine as is.

The unit is back in action- I replaced all caps. For anyone else who runs into a similar situation, just replace them while you're in there. I think I spent about $40 on parts. Not so bad to feel confident I won't be killing another old cap soon and have to do it all over again.

Yes, I know what the pots do! The point is open types get dusty and can put "noise" on the supply rails. New sealed pots are a trifling extra cost.

Dave.