User manual FENDER RUMBLE-BASS

[. . . ] Its' two channels may be operated in combine mode or switch mode. In switch mode, the footswitch (provided) may be used to switch channels or to "A-B" switch between two different instruments. In combine mode, one instrument may be linked to both channels for infinite tonal shaping, or two instruments can be played simultaneously, each with independent control of volume and tone. A "Cut" control on each channel allows a cut in midrange frequencies to suit playing with a pick or for playing slap style. [. . . ] When the control is fully clockwise the signal sent to the speaker jacks is completely "wet". PILOT LIGHT - When this lamp is illuminated the amplifier is receiving power. Should the lamp burn out, turn off the amplifier and unplug it from its power source, unscrew the red jewel, and replace the lamp with type T47 light bulb. CAUTION: WARNING: CHASSIS SURFACE HOT TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK, DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE AVIS: RISQUE DE CHOC ELECTRIQUE NE PAS OUVRIR SUPERFICIE DE CHASSIS CHAUDE SERIAL NUMBER ATTENTION: RUMBLE BIAS AND BALANCE ADJUSTMENT WARNING: Bias and balance are pre-set at the factory. If you are unsure about setting the bias and balance, take your Rumble Bass to the nearest authorized Fender service center. Turn on the amplifier and let it warm up for at least three minutes with the STANDBY switch in the ON position. Remove the front grill to gain access to the bias and balance controls. With a digital voltmeter set to its most sensitive DC voltage scale, insert the Common Probe into the test point BALANCE. Insert the other probe into the test point BIAS2. Adjust the BIAS2 trim until 90 mVDC is obtained. Remove the Common Probe from the BALANCE test point and insert it into the BIAS1 test point. Adjust the BIAS1 trim until 0 mVDC is obtained. It is advised to recheck BIAS2 to confirm that 90 mVDC is still present. With a speaker (or equivalent) load connected to the MAIN SPEAKER jack, run a 1 kHz sine wave through the amplifier. Connect an oscilloscope to the positive lead of a 1/4" phone plug so that you can view the output waveform. Adjust the output signal so that it is just into clipping. Adjust the BALANCE control so that the viewed waveform clips evenly on both the positive and negative peaks. For optimum performance, set the bias to 90 mVDC, then set the balance. If the output tubes cannot be balanced, check the bias setting and/or replace the 6550WA output tubes. RUMBLE REAR PANEL FUNCTIONS A. LINE CORD - Your Amplifier is equipped with a grounding type supply cord to reduce the possibility of electrical shock. Be sure to connect it to a grounded AC receptacle. [. . . ] Be careful not to let any liquid come in contact with the operating surfaces. DO NOT have the amplifier plugged into a power outlet when cleaning. TROUBLESHOOTER'S CHECKLIST - Is the power cord properly plugged into an electrical outlet?- Is the speaker(s) properly connected to the amplifier? [. . . ]