The combined guitar amplifier (kombik) at the wrong connection can strengthen not only signal of electric guitar, but also background of alternating current. That it did not occur, kombik it is necessary either to ground, or to coordinate with the output resistance of the sound pickup.
Instruction
1. Check whether insufficient filtration of power voltage in the most combined amplifier is the reason of background. Disconnect from it all sources of signal, set the loudness regulator to the minimum position. If the background does not disappear, the reason is in electrolytic condensers. Trust their replacement only to the person familiar with safety instructions, especially if kombik is lamp.
2. Examine the socket in which you usually turn on the amplifier. Whether it is equipped with the grounding contact? If yes, take the neon phase indicator, find phase wire with its help, and then, having taken away finger from the sensor, connect the last to the grounding contact by shorter insulated conductor. The bulb has to burn even more brightly, than at contact of the sensor with finger. If it not so, call the electrician and ask it to connect correctly grounding contact, and at its absence - to change also the socket. Do not use substitute ground wires at all: the metal subject driven in the earth, heating radiator, water supply system, zero conductor, and especially - gas pipes.
3. In case the background has not disappeared, check what extender you connect kombik to the socket. Even if the socket is grounded correctly, and the fork of the amplifier has the grounding contact, the effect of grounding will be nullified when using the two-conductor extender. Replace it with three-wire, or connect the device to the socket directly. If the amplifier has special screw for connection of grounding, and the fork is used normal, replace it on another equipped with the grounding contact, having connected the screw to this contact by longer insulated wire, than cord.
4. If the background has not disappeared even after competent grounding, by means of ohmmeter check whether there is no break in cable. Most often the contact of braid - both on the plug, and on the sound pickup departs. Restore this connection. Also measure resistance of the sound pickup and compare it with the input resistance of kombik specified in its instruction. If necessary use the matching transformer.