Variac on zero, power switch off- connect power cord. 2). Connect either output to load box (load A). 3). Resistance loads open (switch in. Gallien Krueger rb Schematic Diagram. Uploaded by esquisof. Gallien Krueger rb Schematic Diagram. Copyright: © All Rights Reserved. Download as. Hello, Service Manual of the Gallien Krueger rb this is a amp for bass, there are layout, pcs, schematics for preamp and poweramp.

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You need some mildly expensive lessons before you try this on a W, especially a “beloved classic”. I’ll just use the pdf’s you sent.

The watt amp schematic would be good to have if avaiable too. For example, I’d rather have reverb always on that be stuck in one channel. 400eb methodofcontrol in forum Other Amps. In the old days I had and 10 ohm resistors at 10 or 20 Watts.

Here’s what I’ve done so far I’m turning some of them back on. Started by Ilya The Lab. A great difference, say between Q8 and Q10, is suspicious.

Can’t see what you done from miles away.

Glad to see someone go the RB schematics uploaded. Can someone check me?


Since I really like how the preamp sounds I’ve been thinking about ditching the power amp and installing something else. This makes me wonder if one of the other parts is still sick. I’ve been looking over the data sheets, and seems close, but another set of eyes that’s familiar with transistor specs would be greatly appreciated. Since my last post I’ve been enjoying this amp, the output was a little hairy at power up but I’m using it in a punk band.

When the IC became history, they made up a small board with long pins, you install it in the same pc board holes and it does the function. Ass-uming that Q9 is exactly 1. Also, it’s generally not as loud as it should be.


Started by Ghengis The Lab. The resistance divider current must be “much” higher. When things go wrong, it gets VERY expensive fast. I think the divider values are about 50 times too small. I’d want to do it different. The output transistors are double-stacked so each gets less voltage. The bases of the outer devices are nominally half the supply voltage, noted as Q4 Q5 flow about 4mA 0.

Gallien-Krueger 400RB Service Manual

Opening it up R50 had burnt up. The obvious solution is: I don’t have much faith in the work that was done to it before I got it.


Education is what you’re left with after you have forgotten what you have learned. I’ve gotten pretty gaallien with tubes but I don’t know anything about transistors so looking at the schematic and the circuit board it’s not adding up to me.

Different transistors kruegrr different areas and doping so the exact voltage needed will vary. In the mean time I’ll have to read that a few more times. I’ll probably just remove the chip and jump the pins.

GK RB schematic

Hey everyone, lrueger apologies for having been absent from this particular thread for so long. When things went wrong, the voltage would fall very fast, the resistors get hot instead of the transistors. Despite not knowing much about transistors I’m pretty sure they’re supposed to be soldered to the circuit board.

I gallien appreciate the schematic for the B or service manual – THX. Each transistor base-emitter drop should be near 0. Soundcraft b schematic Started by Ghengis The Lab.