Behringer SL2442FX , mixer desk, 2004

N

N_Cook

Guest
This 24 ch mixer has been "repaired" twice for a very rare random fault.
Recurs
months after being "repaired". Loss of L channel output at the XLR. Previous
person had obviously looked at the most likely suspect of the 1/4 in sockets
for insert , with bypass contacts and XLRs thmselves.

Both Main/Sub push-push switches, 4 pole C/O are very suspect in the FX
sections, half a mm pushing when out will loose the effects component of L
or R channel and a bit more, full loss of one or both channels. Any other
suspects to check?

I'm surprised the schema are out there but minus smps so some details taken,
just in case.
switcher driver ? (reverse of pcb not explored) maybe designated
04N68, TO220 , usual 0/O possibility (obstructed viewing) other marking
maybe 1M360
 
googling around turned up

"Incidentally, on more than one occasion I have repaired a Behringer with
this exact same symptom (no L ch), and it turned out that one of the main
bus tracks
runs right at the far right edge of the PCB from fader to output jack socket
section. When the PCB was installed into the chassis, something sharp
caught on the PCB and partially cut through the track, which eventually
failed some time later."

for when I get in there proper
 
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:jgjfod$eka$1@dont-email.me...
googling around turned up

"Incidentally, on more than one occasion I have repaired a Behringer with
this exact same symptom (no L ch), and it turned out that one of the main
bus tracks
runs right at the far right edge of the PCB from fader to output jack
socket
section. When the PCB was installed into the chassis, something sharp
caught on the PCB and partially cut through the track, which eventually
failed some time later."

for when I get in there proper
Click to expand...


I have also experienced this exact same problem, it is part of the casing
that does the damage if you are not very careful when fitting the PCB.
The track is VERY close to the edge.



Gareth.
 
Gareth Magennis <sound.service@btconnect.com> wrote in message
news:TMcXq.65159$Uj7.63036@newsfe05.ams2...
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:jgjfod$eka$1@dont-email.me...
googling around turned up

"Incidentally, on more than one occasion I have repaired a Behringer
with
this exact same symptom (no L ch), and it turned out that one of the
main
bus tracks
runs right at the far right edge of the PCB from fader to output jack
socket
section. When the PCB was installed into the chassis, something sharp
caught on the PCB and partially cut through the track, which eventually
failed some time later."

for when I get in there proper






I have also experienced this exact same problem, it is part of the casing
that does the damage if you are not very careful when fitting the PCB.
The track is VERY close to the edge.



Gareth.
Click to expand...
Got into that panel now
Although no observable damage to that trace, I may as well run a line // to
this trace while in there. Looks like that mod, replace the 2 4p c/o sw ,
the 2 1/4 in sockets for Insert and at least remove the main slider ,
probably replace.
Putting some alternate sets to the pins of the interboard headers, and keep
fingers crossed.
After that, should it bounce, I suppose its a matter of building an active
buffer and LEDs as telltales , half way through the outer stages, to
localise down a bit.
I will try and advise the owner to swap to using the upper channels , in
case its a problem earlier on.
 
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:jgjtv6$1ne$1@dont-email.me...
Gareth Magennis <sound.service@btconnect.com> wrote in message
news:TMcXq.65159$Uj7.63036@newsfe05.ams2...


"N_Cook" <diverse@tcp.co.uk> wrote in message
news:jgjfod$eka$1@dont-email.me...
googling around turned up

"Incidentally, on more than one occasion I have repaired a Behringer
with
this exact same symptom (no L ch), and it turned out that one of the
main
bus tracks
runs right at the far right edge of the PCB from fader to output jack
socket
section. When the PCB was installed into the chassis, something sharp
caught on the PCB and partially cut through the track, which eventually
failed some time later."

for when I get in there proper






I have also experienced this exact same problem, it is part of the casing
that does the damage if you are not very careful when fitting the PCB.
The track is VERY close to the edge.



Gareth.




Got into that panel now
Although no observable damage to that trace, I may as well run a line //
to
this trace while in there. Looks like that mod, replace the 2 4p c/o sw ,
the 2 1/4 in sockets for Insert and at least remove the main slider ,
probably replace.
Putting some alternate sets to the pins of the interboard headers, and
keep
fingers crossed.
After that, should it bounce, I suppose its a matter of building an active
buffer and LEDs as telltales , half way through the outer stages, to
localise down a bit.
I will try and advise the owner to swap to using the upper channels , in
case its a problem earlier on.
Click to expand...
 
Got into that panel now
Although no observable damage to that trace, I may as well run a line //
to
this trace while in there. Looks like that mod, replace the 2 4p c/o sw ,
the 2 1/4 in sockets for Insert and at least remove the main slider ,
probably replace.
Putting some alternate sets to the pins of the interboard headers, and
keep
fingers crossed.
After that, should it bounce, I suppose its a matter of building an active
buffer and LEDs as telltales , half way through the outer stages, to
localise down a bit.
Click to expand...



Should it bounce, I suggest you get the owner to buy a new one with a 3 year
warranty for Ł240.

http://www.thomann.de/gb/behringer_sl2442fxpro_eurodesk_24kanalmixer.htm


Probably far more cost effective than hours of repair bills plus parts on an
8 year old mixer probably worth something like Ł70 in good nick on ebay.



Gareth.
 
Force on the 0.25 socket L insert sw about 700gm, to break contact, about
1400 gm on the R to break contact is a bit suspicious. Normally I would
expect problems in the order of 300 or 400 gram contact force. Found a pair
of 4w c/o switches to fit in the 13.5mm of clearance space.
 
To desolder the 4p c/o switches you need to sling .6mm wire under the sw
body and pulling when desoldering. Normal clamp force over the body is
enough to break-up the casing of these very weak switches. At least I could
see inside and no wonder they're problematic.
 
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