Gallien-Krueger 8000RB, 800RB Service Manual

Service Manual

800RB

Table of Contents

Operating Instructions 3

Turn On / Calibration Procedure 6

Schematics 11

Engineering Change Orders (ECOs) 24

Bill of Materials 34

800RB T/O Procedure

GK Doc. # 420-0045-C

Board #’s: 206-0045-C (preamp), 206-0044-A (power amp),
206-0048-A (power supply). 800RB- all options 8/19/91

Setup

1) Variac on 0, power switch off- connect power cord.

2) Connect outputs to load box (100W-> load A, 300W-> load B).

3) Resistance loads open (switch in center).

4) Speaker on (connected to 100W output).

5) Load box to scope-B and AC- VM.

6) Set scope switch on load box to look at load A (down).

7) Set oscillator on 200 Hz sine wave @ 5mVrms (-46dBV).

8) DVM on 20mV (dc) range.

9) Scope –B on 10V/cm.

10) Scope sweep on 1ms/cm, scope trigger on B on RB front panel, set:

11) Tones, masters and boost to 10, switches out.

12) Volume and bi-amp frequency on 0.

Power Supply and Power Amp Test
NOTE: Unless otherwise specified, output levels are in Vrms and taken from 100W output. Flip scope switch up to
load B to see 300W output.

1) Power switch to ON. Gradually turn up variac to 50V, while listening to speaker and watching scope and
ammeter. Output should go negative, then snap back to 0V. Flip switch to check 300W output, also.

2) Check regulated supplies: (+or-) 14.5V, (+ or -) 1V.

3) Adjust variac to 120V and turn speaker OFF.

4) Set bias: 300W- adjust R38 (on ’44 board) for 5mV DC across R48, R49,& R50 (most pos. of the 3) and R54,
R55, & R56 (most neg. of the 3).

5) Set bias: 100W- adjust R14 for( on ’44 board) for 5mV across R25, R26.

6) Power LED and boost LED should be lit.

7) Connect oscillator to input. ( 200 Hz @ -46dBV).

8) Turn on 4 ohm load for 300W amp and 8 ohm load for 100W amp.

9) Adjust volume for slight clipping in 300W amp. 300W output- 36Vrms.

10) Reduce volume for slight clipping in 100W amp. 100W output- 28Vrms.

11) Engage –10dB switch- output becomes 6.0V. Disengage switch.

12) Turn boost to 0. Output becomes 3.1V.

13) Turn master to 0. Output becomes 0V.

14) Turn loads off.

Tones, Filters, and Bi-Amp Test

1) Set bi-amp knob to 0, all others to center (12 o’clock), switches out.

2) Set scope-B to 5V/cm and 1ms/cm.

3) Set oscillator to 200Hz square wave at –46dBV.

4) Look at output, compare to Figure 1.

5) One at a time, turn tone control knobs and compare output to figures (resetting each to center position after
finishing):
A) Treble to 10- Fig.2; treble to 0- Fig.3.
B) Hi-mid to 10-Fig.4; hi-mid to 0-Fig.5.
C) Lo-mid to 10-Fig.6; lo-mid to 0-Fig.7.
D) Bass to 10-Fig.8 bass to 0-Fig.9.

6) Engage Low-cut switch, compare to Fig. 10. (Disengage).

7) Engage Contour switch, compare to Fig. 11. (Disengage).

8) Engage Hi-boost switch, compare to Fig. 12. (Disengage).

9) Engage Bi-amp switch. Compare 100W output to Fig. 13.

10) Compare 300W output to Fig. 14.

11) Set Freq. Knob 10, compare 100W output to Fig. 15.

12) Compare 300W output to Fig. 16. Disengage Bi-amp switch.

Noise Test

1) Remove oscillator input.

2) Turn front panel knobs to 10, switches out.

3) Connect speaker to 100W output and listen for noise. It should be smooth and not crackling. Repeat for 300W
output.

4) Change AC voltmeter range to 1V

5) Noise( both amplifier outputs) should measure less than 400mV.

6) Engage low-cut, contour, and hi-boost. Noise<400mVrms.

7) Volume to 0. Noise< 110mVrms.

8) Boost to 0. Noise<15mVrms.

9) Engage bi-amp switch. 100W noise< 20mVrms, 300W noise< 5mVrms.

RETURN KNOBS TO ZERO, SWITCHES OUT- READY FOR BURN-IN.