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Noise/crackle like from the vinyl at the output ( solution )


Pawel
(@pawel)
Member Moderator
Joined: 2 years ago
Posts: 117
Topic starter  

Hello, just working on the TR2080 and faced the following problem:

- one output from the amplifier had the background noise/crackle. The amplifier board has not been connected to the preamp, etc. I could hear strange crackle at one channel, the second one was ok, just silent. 

I couldn't find the reason, replaced almost all capacitors, checked all active elements, nothing helped. 

A few years ago I was reading the audio forum and found the following comment:

'The theory is that the wire leads of the Hitachi transistor get corroded over time, and that corrosion slowly creeps into the To-92 package, where it corrodes the silicone substrate of the transistor. This can lead to intermittent audio, distorted audio, or high background noise levels. On occasion, an audio channel can go completely dead, but left off overnight, the channel can start working again the next day. Even more annoying, if you pull the transistors out of the tape deck, they test just fine in a transistor tester. If you put a voltmeter on the transistor, then the readings are a mile off from what they should be, so our theory is that the transistor junction breaks down when an operating voltage is applied to it, but under the lower voltage of a transistor tester, they check OK'

Now please look at the picture below and the second leg from the top, I spent two working days....:)

 

IMG 6342

it's fixed now, transistor is replaced and the problem is gone, ufff.

Pawel


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Peca
 Peca
(@peca)
Active Member
Joined: 8 months ago
Posts: 15
 

Hi Pawel, did you replace it with the original part or you used a matched pair. If you used the matched pair which transistors did you use?


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Pawel
(@pawel)
Member Moderator
Joined: 2 years ago
Posts: 117
Topic starter  

Hello

I found the same one at AliExpress . It arrived in a few weeks and it's OK

Pawel


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