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Speakercraft bb50 power amp

Need schematic for a speakercraft bb50 2 chan amp, or the part number for transistors q23 and q33 on the pc board. Called the company, but no help !! Should I bother fixing or just trash it ??

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  • blackhorser Oct 01, 2008

    Dan, the transistor markings are faded, however, q33 has a y??4x on the case, and another marking c2235 and transistor q23 has a bl4h with a c2240 on its case. There is an 8 pin IC close by with a part no. 455800 JRC and 4135G on its case.Also close by is a electrolytic cap c8 ..value is 220 uf@ 25v.





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Can you post the markings on the existing transistors? Also, if these are the output transistors, there shouldbe a complimentary one located close by Q24+Q34 maybe? Post those markings too.


Posted on Oct 01, 2008

  • ABRsvcs Oct 01, 2008

    THe C2235 is actually a 2SC2235, the same for the other C2240 = 2SC2240. Both are common transistors and are inexpensive. The 8-pin IC is a standard opamp IC and can be any of the following:

    MC4558, NJM4558, KA4558 Any of these will works and be the same. Try changing the transistors and the opamp. All together you are talking about less than $5




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**** speakercraft!

Can you post the markings on the transistors themselves? I will look up what I can and try to get you a more common substitute. Post what eve information you can about the transistors and I'll see what I can find. The model and the output specs that are published for the unit would help too. Thanks, Dan

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