[quote name='Phil Starr' timestamp='1353315926' post='1873433']
Crackling is likely to come from damaged pots or connectors, poorly soldered joints or cracks in the circuit boards or from the breakdown of components with electrolytic capacitors going first usually but not always.
there are safety issues and you would need to check the power supply caps are discharged before fiddling around inside the amp. there are several thousand connections inside the amp and resoldering all of them is more likely to end up with you creating other problems especially if there are surface mounted components. You will need a specialist soldering iron with a very fine tip and thermostatic temperature control.
You can often find the fault using a freezer spray but even this is a moderately skilled job, if you can read a circuit diagram and can solder then fine but if not you will probably struggle.
It depends upon you, if you are happy to spend long evenings learning loads of new skills then what have you got to lose, if you want an amp that works then you will have to pay someone who has spent the long evenings learning this stuff.
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Ashdown ABM stuff is simple inside, proper boards, would guess their digital mini ones will be surface mouth stuff.