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Introduzione

This guide takes you through the process of disassembling a small guitar practice amp to access the internals for repair. An Ibanez IBZ10BV2 10-watt bass practice amplifier is used to illustrate the process, but the general procedure applies to most other similar, low-priced solid state practice amplifiers.

  1. Removing the back panel will allow you to access the speaker and main amplifier chassis Make sure that the amplifier is unplugged before starting disassembly Identify and remove the screws holding on the back panel. On my particular Ibanez, 6 Philips head screws are used
    • Removing the back panel will allow you to access the speaker and main amplifier chassis

    • Make sure that the amplifier is unplugged before starting disassembly

    • Identify and remove the screws holding on the back panel. On my particular Ibanez, 6 Philips head screws are used

    • Usually, guitar amplifiers will have a back panel that covers only around half of the amplifier cabinet, while bass amplifiers will have a back panel that seals the cabinet completely

  2. The metal chassis houses the amplifier electronics themselves. You will need to remove it from the cabinet in order to access the power supply and main amplifier circuit board Identify and remove the screws holding the chassis to the cabinet Some mild adhesive may have been used as well. Once you are sure that all screws have been removed, gently push or pry the chassis away from the cabinet
    • The metal chassis houses the amplifier electronics themselves. You will need to remove it from the cabinet in order to access the power supply and main amplifier circuit board

    • Identify and remove the screws holding the chassis to the cabinet

    • Some mild adhesive may have been used as well. Once you are sure that all screws have been removed, gently push or pry the chassis away from the cabinet

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  4. Disconnect the speaker as shown, and remove the power lead clamp from the cabinet The chassis should now be free from the cabinet
    • Disconnect the speaker as shown, and remove the power lead clamp from the cabinet

    • The chassis should now be free from the cabinet

    • Be careful to avoid contact with the main board, as the power supply filter capacitors may still be holding a significant charge

  5. To remove the amplifier board from the chassis, you will first need to remove the volume and tone control knobs Use a flat blade screwdriver to gently pry the knobs off the potentiometer  shafts After removing the knobs, use a socket wrench with the appropriately sized hex bit to remove the potentiometer nuts
    • To remove the amplifier board from the chassis, you will first need to remove the volume and tone control knobs

    • Use a flat blade screwdriver to gently pry the knobs off the potentiometer shafts

    • After removing the knobs, use a socket wrench with the appropriately sized hex bit to remove the potentiometer nuts

    • Make sure to keep the accompanying washers along with the nuts for reassembly

  6. Remove the nut and washer holding the 6.25mm guitar input jack to the chassis Disconnect any wires going from the board to other parts of the chassis, such as to the power switch or power transformer Identify and remove any other screws that might prevent removal of the board. On my Ibanez, two screws held the power amplifier IC heat-sink to the chassis. Removal of the screws and their accompanying lock washers allowed the board to be lifted off with the heat-sink
    • Remove the nut and washer holding the 6.25mm guitar input jack to the chassis

    • Disconnect any wires going from the board to other parts of the chassis, such as to the power switch or power transformer

    • Identify and remove any other screws that might prevent removal of the board. On my Ibanez, two screws held the power amplifier IC heat-sink to the chassis. Removal of the screws and their accompanying lock washers allowed the board to be lifted off with the heat-sink

  7. Electrolytic capacitors can hold a dangerous charge for months or even years after a device has been powered off, thus, it is always a good safety practice to discharge the capacitors before working on an audio amplifier Connect one end of an alligator lead to the chassis ground, and the other lead to an 10K ohm resistor Identify the power supply capacitors and touch the 10K ohm resistor's open lead to each of it's leads for a few seconds
    • Electrolytic capacitors can hold a dangerous charge for months or even years after a device has been powered off, thus, it is always a good safety practice to discharge the capacitors before working on an audio amplifier

    • Connect one end of an alligator lead to the chassis ground, and the other lead to an 10K ohm resistor

    • Identify the power supply capacitors and touch the 10K ohm resistor's open lead to each of it's leads for a few seconds

    • If you are paranoid, you may check with a voltmeter to ensure that the capacitors are safely discharged

    • It should now be safe to work on your amplifier's circuit board

Conclusione

To reassemble your device, follow these instructions in reverse order.

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Santaji

Membro da: 25/03/2011

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