audio-talk

Posted: **Mon Sep 19, 2022 3:59 pm**

I'm having to troubleshoot a DSD DAC project and it seems there is a problem with the BC557 transistors that are supposed to drive the mute switching. I started to dig a bit deeper and it seems that TO92 package BC557 transistors are available with two completely opposite pin-outs, as per datasheets below;

https://datasheetspdf.com/pdf-file/1396 ... mp/BC557/1

https://www.onsemi.com/pdf/datasheet/bc556bta-d.pdf

Is this common?

At the moment, having transistors essentially mounted the wrong way round is my best guess for the problem I've encountered.

Posted: **Mon Sep 19, 2022 4:20 pm**

Unless I am missing something those two documents have exactly the same pin outs. The numbers are different (321 against 123) but they are both the same WRT EBC. Again, am I missing what you mean Ray?

Posted: **Mon Sep 19, 2022 5:37 pm**

+1
agree with Nick
you are misreading the pinout Ray

Posted: **Mon Sep 19, 2022 7:12 pm**

Whoops, that's embarassing, you're both right. I now realise I was just looking at the pin numbers without cross-referencing the labels. Doh!

More head scratching required.

Posted: **Tue Sep 20, 2022 7:37 pm**

I think my head scratching is done, I believe I've identified the issue and will aim to apply a fix at the weekend.

Posted: **Sun Sep 25, 2022 7:57 am**

The DAC is now producing music!

Posted: **Sun Sep 25, 2022 10:15 am**

Ray P wrote: ↑Sun Sep 25, 2022 7:57 am The DAC is now producing music!

Excellent Ray.

"I just wanna hear your sweet beautiful music"

PS Happy birthday.

audio-talk

Head Scratching?

#1 Head Scratching?

#2 Re: Head Scratching?

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