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hey fellas--need a scem. Mark Bass model = mini CMD 121P , Combo Head 2 . Its a small 1x12 combo amp . This one had 1 cap completely melt down and 1 other is burnt + 2 , 5w resistors next to them. Need to know what C87 is , and id like some ideas as to WHY the catastrophic meltdown .
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Designers tend to repeat pet ideas over and over, guess this one should be close enough.
FWIW thisVersion 3 is VERY close to earlier Version 2, what I said before.
https://elektrotanya.com/parsek_mark...wnload.html#dl
Think the latest version has a Class D amp, in that case we are in trouble.
Post a gut picture or two to have a better idea of what you have.Last edited by J M Fahey; 10-08-2020, 04:30 AM.Juan Manuel Fahey -
Hi you won't get the diagram from markbass , tried for years to get mark bass to provide. The amp in question has been repaired and long gone. Too my memory i replaced the main board with a new one. im in the uk i got from a uk supplier price was good.. well worth doing then you have a new bass amp
Please note, that im retired now and my business has been given to someone else
i can't give any more info
bbb
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parts burnt....1 cap not pictured was totally meltedComment
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Sorry for the necropost, but I just repaired A CMD 102P (same amplifier, different speakers in the combo) with the same fault. Figured here was as good as anywhere for posterity.
At least in my case, C86 - 680nF 400V failed first, causing R53 and R54 (4R7 5W) to overheat, leading to C87 (330nF 250V) and C88 (100nF 400V) melting, as they are right next to each other.
All these components, along with L2 and L10, form the class D output filter. L2 and C86 form the first pole, L10 and C88 form the second, and C87 is in series with the parallel pair of R53/54 to form a Boucherot cell/Zobel network. Without C86 to work with L2 to do the bulk of the filtering, R53/54 overheat, with escaped magic smoke and extreme EMI emission being the result.Comment
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Thank you for that information!Comment
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