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Class D Switching Power Amplifiers and Power D/A conversion

LANEY B1 Amp - Blown outputs
LANEY B1 Amp - Blown outputs
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Old 17th April 2009, 07:42 PM   #1
technotronic is offline technotronic  United States
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Join Date: Apr 2009
Default LANEY B1 Amp - Blown outputs


This is my first post to the forum. I am repairing this amp which is using the Tripath TA0104 preamp chip. The output transistors are STW38NB20's (W38NB20) . I have found a supplier with the transistors in stock. At least one is shorted from what looks like a liquid spill near the heatsink where they mount onto.

When powered up, and input signal applied, I can see the LED-VU levels bounce on both the input and output monitoring. There is a green LED near the tripath chip which is not lit, labeled 'run'. Does this mean the Tripath chip is not running and ought to be replaced? I have read about some replacements for this chip which are inconclusive. Ought I just replace it, or is the run light a sign its bad? Nothing else seems burnt, but there are 2 black color hi-watt resistors that dont seem to have any resistance at all, and may be open, but I need to remove them from the board to be sure. They are shown in the photo below each channels power transistors. Thanks.
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