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Repair of 2x Lab Gruppen fp 6400 after power spike from low quality flyback transformers

izzzzzz6

Jan 27, 2021
4
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Jan 27, 2021
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Hi. Has anyone else come across this problem? I have 2x lab gruppen amps that self destructed. The flyback transformer unglued itself where the top bar of ferrite is supposed to be glued to the U shaped piece, this caused a voltage spike which blew some large capacitors and not sure what else yet.
Lab will not sell me a new transformer and they want £600+ to repair each amp.
I told them that this is a design fault and these amps are not worthy of being used as touring amps. No wonder Brick Row must carry 2 of everything when on the road!

Basically, i am hoping to be able to re glue the transformers back together and then to change the capacitors that blew. I'm then hoping they will come back to life as i have 3x of these costing me around £1000 each used price. With those destroying themselves along with my QSC Powerlight 6.0 and a large mistake with a DSP with non working screen blowing 6x 6.5" drivers and my old processor shitting it's pants, it's safe to say i have lost more money than i made over the last few years with this equipment. Depressing to say the least, especially with the current state of affairs, there are more details but i will not bore you all with the situation.

Hoping to find some help here with the rebuilds and wondering if anyone has come across the same situation. I find it had to believe there is no info on this issue online since i already have 2 of these with the same fault.

Also any recommendations on a better glue for shiny surfaces would be appreciated. My first thought is epoxy but i know that it can peel away from shiny surfaces, i also have chemical metal but it's probably too brittle. I'm also wondering if the glue needs to provide an insulation layer and if the gap where the glue sits between the U piece and the ferrite bar is critical?

Thanks.

James
 

73's de Edd

Aug 21, 2015
3,613
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3,613
Sir James . . . . .

MY . . .MY . . . My . . .THATS ONE WHOLE LOTTSA WATTTSA !

In my reviewing the construction of that unit and your mentioning the looseness of the switch mode power supply C core(s).
Look at the bottom where I have replicated that ferrite based Dual D cored power transformer, mainly, due to its full view on the left being blocked by the item 20 heat pipe.
There I show the side to side arrows where I might expect the C cores to move from side to side if the adhesive has failed between them and the internal thin PURPLE insulators, used for allaying / determining full core saturation onset.
Now if they only used an adhesive there between the two cores . . .. where . . . .I ask you . . .WHERE is the point that potentially HARD driven core . . .6400 watts babycakes ! . . . of switch mode power transformer is going to additionally transition into a harmonically related ultrasonic driver and cavitate and fracture any intermediate "hard" bonding adhesive ? ? ?
Look at my insert to the right ,where they used that in bragging on the units small size comparison to an old school iron cored transformer .
On that pic does not my RED lines show . . . .that, surely there is being non metallic plates on top and bottom.
Seems like to me, that units item # 16 photo ADDITIONAlLY needs the ends of the C cores capped with the required oversize rectangular mechancal reinforcement / clamping pressure insulative plates.
Being made of Delron-Nylon-Teflon- fabric Bakelte - or matte molded fiberglass + expansion hard rubber sheet spacers. That then permits cross clamping and secrely pulling the C cores together with nylon hardware or spacers . . . as the AVALABLE . . . .crossing space will permit.
I see that the "21" black aluminum divider has rectifiers mounted to it . . .any chance that the "20" heat pipe sides twin divider has nothing mounted on it. If so, that would give that divider use for passing clamp hardware thru it into an initial insulated spacer between the divider and the left C core piece .
Also in the top of the photos "D" audio amps, you can see the two plus two ferrite grey bobbin cup inductors that have spring clip clamping at their ends as well as a probable bead of hard epoxy around their center seams.

You can certainly see and examine the potentially involved mechanics better than I am able to see in the photo.

Thaaassssssssit . . . .

6400 WATTS ! . . .BABYCAKES !

Le Product . . . . .Gruppen
Lab-Gruppen-fp6400-AMP.png



73's de Edd . . . . .

Jes' tink about dis a bit . . . . . A pat on the back is only a few inches up from a kick in the pants.




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