Sound Is Sometimes Disappearing; Some Of The Controls On The Front Panel Aren’t Working Properly - Warwick WA600 Service Manual

Sound is sometimes disappearing:

1. Try to use different instrumental cable and/or different guitar.
2. Try to move jack plug while it's inserted in preamp jack inputs (passive and active) and listen if sound depends on
cable movement. If it does then preamp needs to be exchange.
3. Try to move each of potentiometers and listen if sound is disappearing, or you hear any unwanted noises on this
movement. If it does then preamp needs to be exchange.
4. Disassembly amp.
5. Perform ribbon cable test.
6. Connect all parts back together, turn on the amp, try to move ribbon cable close to the both endings and listen if
sound depends on cable movement.
7. Perform all other tests. Pay attention during each test if any movement (of components, connectors, electronic
boards) affects test results.
Some of the controls on the front panel aren't working properly:
1. Disassembly amp.
2. Perform preamp test.