Soundcraft LX7

[Lamplighter]

Has anyone had a problem with outputs vanishing and later re-appearing on an LX7. I am just about to open up to take a look at one. At various times one of the main outputs, Aux 1 or group one have gone. The missing output is still registering on the Led meter but not appearing at the output socket. Soundcraft are not aware of this as a problem. It has happened at different locations but never when back in the workshop when there is time to open it up. Ideas anyone?

 

Brian

[Bobbsy]

In the deep and dusty past I had similar once when I was taking the balanced outs to an unbalanced input....

 

Bob

[James]

Yes,

 

I've had this problem a couple of times. It's a bit of a pig of a job but inside the LX7 the main printed circuit boards are linked by ribbon cable, these ribbon cables come from very week header blocks and can often do with re-seating. (particularly if you have had outputs go awol)

 

good luck, (and don't loose any screws)

 

James

[lonfire]

hi,

its funny you should mention this.. I'm sure our LX7 has a problem with AUX2 coming and going.. I've never pinned it down.. I tend to avoid using it..

 

let me know if you suss it

 

rgds

chris

[Lamplighter]

Thanks all you fine gentlemen, I will be taking the plunge inside this evening. I will let you know if I find anything interesting.

 

Bob

 

Your comment re unbalanced inputs is interesting, though from memory all the affected outputs were connected to differential inputs in some form.

 

James

 

I'll send you the screws left on the bench when I get the lid on!.

 

 

Brian

[Jim]

Yes,

 

I've had this problem a couple of times. It's a bit of a pig of a job but inside the LX7 the main printed circuit boards are linked by ribbon cable, these ribbon cables come from very week header blocks and can often do with re-seating. (particularly if you have had outputs go awol)

 

good luck, (and don't loose any screws)

 

James

<{POST_SNAPBACK}>

 

This is definitely a problem I've heard before from a few LX7 users; although it's not just a Soundcraft thing. There are plenty of nice expensive boards with cheap horrible ribbon connectors. It's often worth taping the connectors in (tape because you can still unplug them if you're taking the desk to bits).

[Lamplighter]

Well I spent my evening with head buried inside said LX7. The main output initially came and went as I moved the loom from the main board containing the masters, to the output connector board, then suddenly all was well, unable to lose output. The headers were correctly seated but the soldering of header to main board left a lot to be desired. Lots of reflow with an RF iron and fresh solder. Now to sit back and see if that is the answer. I really hate it when I can't properly reproduce the fault. I think the next stage is to bypass the headers with direct wire to board joints. I have had similar problems on top end comms consoles and bypass is the only reliable answer.

 

James, sorry no spare screws this time, I'll have to try harder in future.

 

Brian

[Silver_Rayne]

someone recently purchased an LX7II for my theatre. (1 week before I started) And only this afternoon was I having the same troubles. There seems to be an intermittent link between the groups and the main out I thought it may have been an external cabling issue with the group inserts but now I may have to look internally for the problem.

Doesnt help that none of the music tech students can differentiate one type of cable from another.

Eternally useful thread cheers.

 

Will more than likly have screws left allway do even from chocblok sometimes, I think they breeb in the toolbox.

[Lamplighter]

How time flies. I was reading this when I realised that the soldering session must have done the trick. No further disappearing signals since April.

Declan

you might want to check the group to mix switches, they would give exactly the described effect if depressed.

 

Brian

[Silver_Rayne]

yepps been through all that. it will be working one second then you take a group out and try to put it back in and nothing. occasionaly switching the group out of mix then back in dos the trick but not allways.

[Lamplighter]

That sounds very like the ribbon connector problem.

 

Brian

[Silver_Rayne]

oh boy that was interesting. Was expecting a bit of movement but that was poor. all fixed now though have had 6 hours solid uninterupted sound out of it today. With the exception of some patch cables deciding not to be present for most of the day. cheers for a usefull thread again.

[mr.purple]

Aha ...this is what the site should be all about good helpfull advice.

 

I have had several LX 7s 16 and 24s all exhibit the same fault Aux 3 dissapears then when you give it some !! it magically comes back in

 

I dont use in ears on aux 3 now !!

 

I will have a look at the latest faulty one and see if I can replecate and repair the fault#

 

Ill let you know

 

 

MrP

 

If God is a DJ we are all quids in as he will need someone to fix all his busted kit !

[timsabre]

This is a reply to a really old post... but we still have an LX7 at our church and in our case this problem is caused by dirty contacts on the insert jacks (which should loop through when nothing is plugged in, but gradually seem to go high impedance if not used).

Plug a jack into all the inserts a few times and see if that fixes it.

[Miha Blaze]

great thread!!!

 

I have recently bought (used) lx7ii (24ch) and noticed one problem... sometimes few channels are distorting (like you put your voice through guitar distortion pedal or something similar), or not realeasing the signal at all... and after I touch mic pre pot a bit, problem dissapears... anyone know what is wrong? I am not electronically educated so this is all I can tell you about this issue....

 

Cheers!