Sujet Panne ADA 8000 ... une alim mal concue

Basically here's a quick rundown of the mod so far:

undo all the screws on the 8 XLRs and the 2 fiber optic connectors on the rear panel. (18 screws total)
Remove the screws holding the PCB to the chassis (4 screws)
'shuffle' the circuit board up to gain access to the solder side.

Desolder these diodes at the POSITIVE end: (the end with the white band!)
D11 & D10 (positive node of the +5V bridge)

D7 & D6(positive node of the +48V bridge).

D20 & D21 (positive node of the ±15V bridge)

Desolder these diodes at the NEGATIVE end: (the end WITHOUT the white band!)
D22 & D23 (negative node of the ±15V bridge)

Okay, Double check that you've lifted the correct end of each diode. (-On my PCB, the screen printed legend for each and every diode happens to correspond with the end that you have to lift; yours may be the same, but DOUBLE-CHECK!!!)

Bend the free ends of D6 & D7 together and solder them to form a node.

Bend the free ends of D10 & D11 together and solder them to form a node.

Bend the free ends of D20 & D21 together and solder them to form a node.

Bend the free ends of D22 & D23 together and solder them to form a node.

Cut a dozen or so 4" or 5" (100-125mm) lengths of insulated hookup wire, of gauge strong enough to handle an amp or two, (specially for the 5 volt rail!).

Cleanly solder one end of a piece of wire into the now-empty hole which used to be occupied by D6.

Solder one end of a second piece of wire into the now-empty hole which used to be occupied by D10.

Solder one end of a third piece of wire into the now-empty hole which used to be occupied by D20.

Solder one end of a fourth piece of wire into the now-empty hole which used to be occupied by D22.

Re-mount the board in the chassis and replace the screws. Be particularly careful with the screws into the optical connectors: DO NOT force the screw in without supporting the back of the connector strongly, or you can break the pins away from the board... (ask me how I know! ...although not with one of these particular units...)

Now, each rail mod is essentially a reservoir (smoothing) cap followed by a power resistor. The rectifier output of each rail will go across a smoothing cap (the other end of which is referred to 0Volts), then through a power resistor, and back to the board.

The idea is that some ripple current is relieved from the on-board smoothing cap by the newer (and bigger!) capacitor, then the raw voltage will be reduced off-board[/u] to a more manageable voltage, moving much of hte heat load from the regulators. In addition, the on-board capacitor now forms the shunt leg of an RC stage, smoothing the voltage still further.

So, the resistor and capacitor values which seem to work so far, are as follows:

+5V:
4700µF/16V
10 Ohm, 10Watt (ceramic)

+18V:
1,000µF/35V
25 Ohm, 25Watt (metal body)

-18V:
1,000µF/35V
25 Ohm, 25Watt (metal body)

48V rail values:
Capacitor: 150µF/100V
Resistor: 200 Ohm, 5Watts.

So here's how I've done it so far:
In addition to the wires soldered to the lower side before we put eh board back in, we need to solder one more wire, onto the NEGATIVE end (the end without the white band!) of D8. -This is our modification 0V for all of the rails, and we'll be 'star-connecting' one end of the capacitor for each rail modification to it.

+5Volt Rail Mod: securely Mount a 4700µF/16V capacitor inside the case.
Run the wire from 0Volts (the negative end of D8) to the NEGATIVE terminal.
Solder a new length of wire from the junction node of D10 & D11 to the positive terminal.
Solder a second connection to the positive terminal, to one end of the 10 Ohm/10W resistor.
Locate the unconnected end of the wire going to the hole vacated by D10, and solder it to the remaining terminal of the 10O resistor.

+18Volt Rail Mod: securely Mount a 1000µF/35V capacitor inside the case.
Run the wire from 0Volts (the negative terminal of the cap in the +5Volt rail mod) to the NEGATIVE terminal of the 1000µF cap.
Solder a new length of wire from the junction node of D20 & D21 to the positive terminal.
Solder a second connection to the positive terminal, to one end of the 25 Ohm/25W resistor.
Locate the unconnected end of the wire going to the hole vacated by D20, and solder it to the remaining terminal of the 25O resistor.

-18Volt Rail Mod: securely Mount a 1000µF/35V capacitor inside the case.
Run the wire from 0Volts (the negative terminal of the cap in the +5Volt rail mod) to the POSITIVE terminal of the 1000µF cap.
Solder a new length of wire from the junction node of D22 & D23 to the negative terminal.
Solder a second connection to the negative terminal, to one end of the 25 Ohm/25W resistor.
Locate the unconnected end of the wire going to the hole vacated by D22, and solder it to the remaining terminal of the 25O resistor.

+48Volt Rail Mod: securely Mount a 150µF/100V capacitor inside the case.
Run the wire from 0Volts (the negative terminal of the cap in the +5Volt rail mod) to the NEGATIVE terminal of the 150µF cap.
Solder a new length of wire from the junction node of D6 & D7 to the positive terminal.
Solder a second connection to the positive terminal, to one end of the 200 Ohm/5W resistor.
Locate the unconnected end of the wire going to the hole vacated by D6, and solder it to the remaining terminal of the 200 Ohm resistor.

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J'ai pas tenté la manoeuvre... sur un des miens, après la mort d'un régulateur, j'ai rajouté des dissipateurs sur tous les régulateurs (pour le moment ça tient)... mais si ça recommence, va falloir que je sévisse..
m'enfin.

Pour les désespérés, on trouve également des transfos neufs pour cet appareil chez PMS, en allemagne :
http://pms-electronics.com/shop1/oxid.php/sid/e2d77bfa842043860ffc0e714da9bddb/cl/details/anid/4843efd240bd89.84350182/TRAFO%3BTOR%3BADA8000%3BEU%3BTI%3BC//listtype/search/searchparam/968-41879-31791

Bon, là, comme ça, j'en vous qui ont subitement un air inquiet en regardant leur ADA8000... meuh non, c'est une bonne machine, sinon, m'sieur behringer aurait probablement jeté l'éponge depuis un moment, et si on se donne la peine de la retaper, c'est parcequ'on l'aime bien... mais si vous avez un pb d'alim... ben ce post vous aidera peut être.