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Dismantling an amp - what is the circular thing?


Clarky
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I have to send back my faulty Acoustic Image Contra to the US for repair. This comprises a head bolted on to a speaker. I was told "you don't have to remove the whole chassis, just take the top off (with the preamp attached) and then remove the rear panel (with the power amp attached) and send us those two units."

So I've unscrewed everything and the front panel is self explanatory. When the say rear panel with power amp attached, do they mean the big circular thingummy that comprises densely coiled wires in a plastic type covering?

Thanks in advance from an electronics numpty :)

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[quote name='Clarky' post='1193587' date='Apr 9 2011, 10:29 AM']I have to send back my faulty Acoustic Image Contra to the US for repair. This comprises a head bolted on to a speaker. I was told "you don't have to remove the whole chassis, just take the top off (with the preamp attached) and then remove the rear panel (with the power amp attached) and send us those two units."

So I've unscrewed everything and the front panel is self explanatory. When the say rear panel with power amp attached, do they mean the big circular thingummy that comprises densely coiled wires in a plastic type covering?

Thanks in advance from an electronics numpty :)[/quote]

Sounds to me like its the mains transformer. A picture would help.

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Without pics its a bit difficult but it sounds like a torus transformer. Its part of the power supply but not directly part of the power amp. Its also probably the heaviest thing in the whole thing so if you can get away without posting it you may save a few pennys!

A

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[quote name='obbm' post='1193591' date='Apr 9 2011, 10:32 AM']Sounds to me like its the mains transformer. A picture would help.[/quote]
There's a panel with lots of electronc-y stuff and its attached by wires to something very similar to this thing

[attachment=77035:Professi...nsformer.jpg]

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[quote name='Clarky' post='1193595' date='Apr 9 2011, 10:35 AM']There's a panel with lots of electronc-y stuff and its attached by wires to something very similar to this thing

[attachment=77035:Professi...nsformer.jpg][/quote]

If it's going back to the States then they may not need it, but check with them. If you have to disconnect it then take lots of photos, make notes and a diagram so you know how to put it back together.

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Thanks all. I will disconnect the toroidal transformer as it sounds like this is not needed. TBH, the head isn't much bigger than the parts I would be sending off and its metal casing protects the electronic innards. Seems very odd to me to send the guts - I will need a ton of bubble wrap to make sure it doesn't get damaged on route. But I guess this is what Acoustic Image do and if it led to laads of problems they would have stopped doing it?

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[quote name='obbm' post='1193603' date='Apr 9 2011, 10:39 AM']If it's going back to the States then they may not need it, but check with them. If you have to disconnect it then take lots of photos, make notes and a diagram so you know how to put it back together.[/quote]

And it will probably involve a soldering iron!! Im sure thats in the small print of the warranty!! Not to put the fear of god into tyou Clarky but sending it to an appointed repairer in this country sounds like a much more 'customer friendly' option to me.

A

Edited by apa
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[quote name='apa' post='1193605' date='Apr 9 2011, 10:43 AM']And it will probably involve a soldering iron!! Im sure thats in the small print of the warranty!! Not to put the fear of god into the op but sending it to an appointed repairer in this country sounds like a much more 'customer friendly' option to me.

A[/quote]
There is no appointed repairer unfortunately. Overwater distribute and they told me to send to the US

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You don't say what the problem is, but if it turns out to be caused by a faulty power supply they would need the transformer. I'd give them a call to make sure. Are you sure there’s no one over here who could fix it?

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[quote name='Clarky' post='1193607' date='Apr 9 2011, 10:44 AM']There is no appointed repairer unfortunately. Overwater distribute and they told me to send to the US[/quote]

Im sure evrything will be fine. Like you say, it sounds like standard practice and plenty of pics will do the job :)

A

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[quote name='Clarky' post='1193607' date='Apr 9 2011, 10:44 AM']....There is no appointed repairer unfortunately. Overwater distribute and they told me to send to the US....[/quote]
I'm sure the Bass Gallery will know someone.

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[quote name='chris_b' post='1193610' date='Apr 9 2011, 10:47 AM']You don't say what the problem is, but if it turns out to be caused by a faulty power supply they would need the transformer. I'd give them a call to make sure. Are you sure there’s no one over here who could fix it?[/quote]
It just stopped making sound above the level of a mouse squeaking in a rehearsal last week (and the effects/send doesn't override this) - AI think the power amp has gone, based on my rather more detailed description of events. I did ring Overwater to see if there's anyone else but they only recommended sending back to AI. To be honest I will be selling this combo when it is fixed (as I have had to buy an emergency replacement for a big gig tonight) and I would rather any would-be buyer had the AI 'guarantee' attached to the repair work.

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Thanks all for advice. Fortunately the toroidal transformer was clipped rather than soldered on, so it was a simple exercise to disconnect it (and it has colour coded wires for when I eventually re-connect, making that process simple too). For peace of mind's sake I would rather have sent the whole unit but its all bubble wrapped and bagged up now, hopefully safely. Cheers again!

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[quote name='Clarky' post='1193617' date='Apr 9 2011, 10:52 AM']It just stopped making sound above the level of a mouse squeaking in a rehearsal last week (and the effects/send doesn't override this) - AI think the power amp has gone, based on my rather more detailed description of events. I did ring Overwater to see if there's anyone else but they only recommended sending back to AI. To be honest I will be selling this combo when it is fixed (as I have had to buy an emergency replacement for a big gig tonight) and I would rather any would-be buyer had the AI 'guarantee' attached to the repair work.[/quote]

Is this AI under warranty?

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[quote name='icastle' post='1193686' date='Apr 9 2011, 12:12 PM']Is this AI under warranty?[/quote]
Probably not (its the older IIa series) - Beedster got it off eBay and I bought it off him so would be difficult to track down history. That said AI have indicated they will repair for free :)

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[quote name='apa' post='1193599' date='Apr 9 2011, 10:37 AM']Yep thats a mains transformer all right!!

I think its a bit bad form for them to expect you to dismantle one of their units for them!! What if you cocked something up? who would pay for THAT repair???

A[/quote]
+1

Bad form indeed - especially when, presumably, they expect you re-assemble the repaired parts as well. Ludicrous.

Imagine a car company that required you to remove a faulty engine and return it to the manufacturer for them to fix under warranty and then you have to re-install it in your car. We'd laugh them out of the showroom for taking the p*ss.

Edited by flyfisher
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[quote name='flyfisher' post='1193951' date='Apr 9 2011, 06:13 PM']+1

Bad form indeed - especially when, presumably, they expect you re-assemble the repaired parts as well. Ludicrous.

Imagine a car company that required you to remove a faulty engine and return it to the manufacturer for them to fix under warranty and then you have to re-install it in your car. We'd laugh them out of the showroom for taking the p*ss.[/quote]

I refer you to Clarky's previous post:

[quote]Probably not [under warranty] (its the older IIa series) - Beedster got it off eBay and I bought it off him so would be difficult to track down history. That said AI have indicated they will repair for free[/quote]

Pretty good form, if you ask me.

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[quote name='yorks5stringer' post='1193993' date='Apr 9 2011, 07:17 PM']It's a bit late now, but isn't there something about "discharging" a transformer before you start fiddling with it as it retains its mains voltage?[/quote]

Nope.
That's the smoothing capacitors - but they only retain the voltage the transformer is stepping down to.

Edited by icastle
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"No User-Serviceable Parts Inside" is a common sticker on all manner of consumer products these days, presumably to absolve the manufacturer from any liability arising from people trying to replace faulty components when they don't know what they're doing.

Perhaps this is a new initiative to make products that actually can be economically repaired instead of just being treated as disposable items.

I wonder what the H&S police would have to say about such things?

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