Searching for a spare part (ic for Beosound 9000

[KolfMAKER]

Hi Edo, thanks for your update.

I actually think this is progress. The fact that replacing the TDA1305T did not change the behaviour strongly suggests that the DAC itself was not the root cause. What I find more interesting is that:

• cooling around C401/C403 restores the sound,
• replacing C401/C403 did not solve the problem,
• and TR405 starts oscillating when the audio disappears.

That makes me wonder whether C401/C403 are simply close to the actual faulty component, rather than being the fault themselves.

At this point I would focus on TR405 and the components directly around it. It may be useful to measure the base, collector and emitter voltages of TR405 before and after the fault occurs.

Once the freeze spray arrives, I would also try cooling TR405 and the surrounding components individually rather than cooling a larger area of the PCB. To me, TR405 and its local circuitry now look like stronger suspects than the DAC.

Location: The Netherlands

Favourite Product: BeoSound 9000

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