Évaluations - 1, GPA: 3
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Facilité d'utilisation
• Did the Mains voltage fluctuate or spike while the amp was on? In all-tube amps, over-voltage surges in the Mains net can certainly cause drop-outs. Over-voltages are often caused by generators and faulty high-current power circuits. • Perhaps a fuse blew even though none of the tubes is actually defective? An old fuse, tube de-ionization or Mains voltage power surges may have triggered the fuse. Things to Bear in Mind When Replacing Tubes Replacing tubes is a job best left to qualified professionals! Accordingly, the following guidelines are addressed and apply to qualified service technicians only: • Pull Statesman’s Mains plug and allow for a discharge time of at least two minutes before removing the chassis from the rear of the amp. • The upright mounted preamp and power amp tubes of all Statesman combos are seated in a self-contained chamber that is easily accessible from outside. And so they are optimally protected against vibrations through the loudspeaker’s vibrations. Illustration: QUAD EL 84, 2x 12AX7, 4x EL84 • After removal of the protective grid, the measuring points and controller for setting the correct bias current and the heating symmetry (“hum balance”) are also directly accessible. Illustration: QUAD EL 84. • The illustration shows (from left to right) the aperture for the bias trimmer, the jumpers to the measuring points, and the aperture for the trimmer to the hum balance. The two trimmers may not be mixed up, since otherwise there is a danger of output stage damage through excessively high current in the tube! english Absolutely pay attention to preparations and chronological order! 1. Turn off the device 2. Exchange tubes 3. Remove all jumpers 4. In tubes with the same characteristic curve, do not change the position of the bias trimmer. In tubes with unknown characteristic curve, turn the bias trimmer to the right-side stop (lowest current). 5. Turn on the device 6. Measure and adjust the bias current (equivalent voltage): The jumpers bypass a shunt resistor. When removing the jumpers, the cathode current can be determined via the exposed pins through a voltage measurement. The following applies in this connection: 1 mV is equivalent to 1 mA. The order of the jumpers from left to right corresponds to the order of the appurtenant tubes from left to right. The bias current is correctly adjusted if a voltage between 16 and 21 mV is applied to the pins (between the upper and lower pin of the respective jumper) with all tubes. If this voltage range cannot be adjusted to all tubes, the divergent tubes must be exchanged and a suitable tube must be found. For this reason Hughes & Kettner offers selected tube sets with similar characteristic curves. 7. Turn off the device 8. Put on all jumpers. Attention: Do not forget to put the jumpers on again after successful alignment! Never operate the amp without jumpers! 9. Turn on the device 10. Carry out hum balance Basic setting: Switch the amp to CLEAN, turn VOLUME, TREBLE and MID to the left-side stop, and turn BASS to the right-side stop. With the help of the trimmer, look for a setting in which the lowest humming emerges. 11. Mount the protective grid again 4. Possible Error Sources / Troubleshooting Mains connection: STATESMAN won’t power up when you switch it on. • It‘s not getting AC power. Check the Mains cord to see if it is connected and firmly seated. • The Mains fuse is defective. Ensure it is replaced with another fuse bearing the same rating. • The local Mains voltage does not match Statesman’s operating voltage Available Voltages and How to Adapt Them Statesman ships in two versions rated for 110/120V and 220-240V. You will find the rating indicated on the housing above the Mains socket. Both models offer two operating voltages that are selected using the voltage selector integrated in the Mains socket. Ensure that the Mains voltage matches the voltage rating appearing in the voltage selector window. This value is legible when the amp is in the standard operating position, that is, placed right side up. The upright number indicates the currently selected voltage, and the inverted number indicates the alternative voltage. Check also the fuse ratings to ensure they match the ratings indicated on the rear panel. Voltage selection and fuse replacement may be performed by experienced service technicians only. Accordingly, the following notes are addressed exclusively to service technicians: • Use a small flat screwdriver to remove the voltage selector from the Mains socket. • If the fuse is defective, replace it with a fuse bearing the specified rating. • Turn the voltage selector and insert it back into the port so that the desired Mains voltage rating is legible and appears at the top left (next to the “Voltage Setting” arrow). Statesman is connected properly, but no sound is audible. • The guitar’s VOLUME knob is turned all the way down. • The amp’s VOLUME knob is turned all the way down. • The effects loop is active and set to SERIA...
Ce manuel est également adapté pour les modèles :Instruments de musique - Statesman QUAD EL84 (2.15 mb)