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FBT Maxx 2a, powered speaker, 2002

Small lighting unit and this powered speaker shared cheap and nasty plastic multiway mains adaptor. Much crackles and bangs from bad contacts in the adaptor but both survived working order . This amp had smoke coming from it, at the time of the crackling. The bridge rectified 52-0-52V ac supply used to have a cap across it, burnt up to just 2 pins now. Only FBT schema, out there found, is for the MAX 9SA for which that component is 100nF 200V , so replace with disc ceramic of that rating or higher? or C +R ? and of course advice to obtain metal cased mains multiple adaptor.

Reply to
N_Cook
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The owner may have interpretted as bad multiway mains connector.

This capacitor was .2 inch spacing, same as the one over the bridge for the tweeter amp supplies. That shows no heating at all. That one is mustard yellow 6x2.4x4.2mm high, marked K2R

104K That one must be 100 V rating at least, so probably MLCC for that size, certainly if 200 V rating. The burnt one , same footprint may have been taller or 100V rating only. Probably started with metal migration and MLCC failure , yet again , starting with going ohmic down internal micro-fractures then conflagration eventually, rather than bad adapter leading to multiple mains spikes
Reply to
N_Cook

the

Will probably replace with 4 as 2x2 100nF/100V traditional disc ceramic for

4x power rating and one in place of the K2R one
Reply to
N_Cook

I had to change the gain pot The gain pot on these is reverse log , probably more like reverse log-log, for the 5K pot the half-way split was .28K/5.1K , so a log pot slightly adapted and 2 ends cut and cross-linked wiring

Reply to
N_Cook

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