boatman Posted January 25, 2015 Share Posted January 25, 2015 I have been asked to repair a Spirit F1 (8 mic + 2 stereo channels) which has an intermittent fault on the main output. The AUX outputs appear to be OK so I suspect the main faders or that section of the PCB. I have found schematics on the web and the back of the case comes off easily enough. How do I get to the front side of the circuit board? It looks as though all the knobs have to come off, all the front panel screws and those retaining the XLR connectors as well as all the jack socket rings. By the time I've done that there won't be much holding it together and I don't want to end up with it collapsing like a house of cards! Any hints would be welcome. Edited for SPAG. Link to comment Share on other sites More sharing options...
Simon Lewis Posted January 25, 2015 Share Posted January 25, 2015 It's a very distant memory, but isn't that desk built on a single circuit board? If so, your plan of attack sounds about right! Link to comment Share on other sites More sharing options...
Lamplighter Posted January 25, 2015 Share Posted January 25, 2015 I've had the boards out of a folio sx and an LX7 at various times. Its not difficult , remove the cover, support the board on some carpet or sheeting then just undo everything from the front. The board is quite robust, just watch the power supply lead to the case. It is tedious but not difficult.Brian Link to comment Share on other sites More sharing options...
bruce Posted January 25, 2015 Share Posted January 25, 2015 Useful trick: (at least, it was useful when I was doing a similar job on a Mackie) - if the pots are mounted with nuts, rather than just poking through the top panel, and you don't have a suitable sized box spanner, use a small socket (without drive) to remove them - it'll slip over the pot, with the pot shaft slipping up the hole where the square drive would be. Sounds blindingly obvious - but if you've got dozens of pots to undo, it makes things a bit easier. Link to comment Share on other sites More sharing options...
boatman Posted January 25, 2015 Author Share Posted January 25, 2015 Thanks all. I got the front panel off and it's all surface mount components. An inspection under a magnifying glass doesn't reveal any cracked solder joints so I'll just clean the faders, put it back together again and run a soak test to see what happens. Link to comment Share on other sites More sharing options...
sandall Posted January 25, 2015 Share Posted January 25, 2015 Doesn't solve your problem, but I've got an F1 that intermittently loses the ground between the +/-20(?)v rails, giving horrendous buzz on all outputs. I discovered that when it happens one rail goes to about 35v & the other to about 5v. I've changed the regulators, caps & bridges & re-soldered all the joints on the power bit of the PCB, without success. Anybody got any ideas before it hits the local recycling centre? Link to comment Share on other sites More sharing options...
Dave m Posted January 25, 2015 Share Posted January 25, 2015 We used to have a couple and one would buzz horribly unless given the other's power supplyThe second one seemed to be ok with either. Link to comment Share on other sites More sharing options...
Rob_P Posted January 25, 2015 Share Posted January 25, 2015 I had a spirt notepad that did exactly that. The standard 3 pin plastic power plugs are rubbish and the ground connection was intermittent, resulting in a horrible buzz. I swapped mine for a mini XLR and it solved it Link to comment Share on other sites More sharing options...
sandall Posted January 25, 2015 Share Posted January 25, 2015 I had a spirt notepad that did exactly that. The standard 3 pin plastic power plugs are rubbish and the ground connection was intermittent, resulting in a horrible buzz. I swapped mine for a mini XLR and it solved it That's just reminded me that my original Notepad came with a dodgy power socket. I got the mixer replaced under warranty & totally forgot all about until your post. If I haven't totally destroyed the PCB with all my component swapping (all the plated holes come out with the component pins) I'll try again with a different connector. Thank you. Link to comment Share on other sites More sharing options...
boatman Posted January 25, 2015 Author Share Posted January 25, 2015 ..I got the front panel off and it's all surface mount components. An inspection under a magnifying glass doesn't reveal any cracked solder joints so I'll just clean the faders, put it back together again and run a soak test to see what happens. Finally got it back together (what a fag that is) and it's been running for nearly six hours and is still going strong so it looks as though it was just the faders needing a good clean. It hangs on the wall in a local restaurant so they were probably full of grease. Link to comment Share on other sites More sharing options...
J Pearce Posted January 27, 2015 Share Posted January 27, 2015 The other thing to watch for on intermittent main outs is the switching contacts in any insert jack sockets. It's tedious taking that sort of Soundcraft desk apart, but they are quite well built and easy to put back together. I spent my school work experience building, testing, and repairing kit at the Soundcraft factory, had a good time and reminded me that I really didn't ever want to work on a production line. Link to comment Share on other sites More sharing options...
boatman Posted January 27, 2015 Author Share Posted January 27, 2015 The other thing to watch for on intermittent main outs is the switching contacts in any insert jack sockets. It's tedious taking that sort of Soundcraft desk apart, but they are quite well built and easy to put back together. I spent my school work experience building, testing, and repairing kit at the Soundcraft factory, had a good time and reminded me that I really didn't ever want to work on a production line. Thanks. I did clean the insert jacks whilst I had it open. Link to comment Share on other sites More sharing options...
richardash1981 Posted January 27, 2015 Share Posted January 27, 2015 Doesn't solve your problem, but I've got an F1 that intermittently loses the ground between the +/-20(?)v rails, giving horrendous buzz on all outputs. I discovered that when it happens one rail goes to about 35v & the other to about 5v. I've changed the regulators, caps & bridges & re-soldered all the joints on the power bit of the PCB, without success. Anybody got any ideas before it hits the local recycling centre?The centre tap of the supply transformer has certainly come loose. Might be the connection between the transformer and the board, or even inside the transformer if the enamelled wire has cracked due to flexing? I've had this with an induction loop amplifier, which then followed the voltage imbalance up by blowing both supply capacitors... This turned out to be a dud crimp inside the plug linking the transformer to the PCB, once this was fixed, it all worked fine again. Link to comment Share on other sites More sharing options...
sandall Posted January 28, 2015 Share Posted January 28, 2015 Don't think it's the transformer, as I tried another PSU, so it looks like the centre pin on the power socket (there's good continuity from the socket to the PCB). Isn't hindsight wonderful? Link to comment Share on other sites More sharing options...
sam.spoons Posted January 29, 2015 Share Posted January 29, 2015 If it's the same as my old SX20, the power plug/socket looks distinctly dodgy. Actually mine never gave trouble but I was always concerned that it might. I did repair a folio Notepad with a similar power socket, I replaced it with a captive lead. Link to comment Share on other sites More sharing options...
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