Head Scratching?

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Ray P
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#1 Head Scratching?

Post by Ray P »

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.
Sorry, I couldn't resist!
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Nick
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#2 Re: Head Scratching?

Post by Nick »

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?
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ed
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#3 Re: Head Scratching?

Post by ed »

+1
agree with Nick
you are misreading the pinout Ray
There's nowhere you can be that isn't where you're meant to be
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Ray P
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#4 Re: Head Scratching?

Post by Ray P »

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.
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Ray P
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#5 Re: Head Scratching?

Post by Ray P »

I think my head scratching is done, I believe I've identified the issue and will aim to apply a fix at the weekend.
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Ray P
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#6 Re: Head Scratching?

Post by Ray P »

The DAC is now producing music!
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pre65
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#7 Re: Head Scratching?

Post by pre65 »

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.
The only thing necessary for the triumph of evil is for good men to do nothing.

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G-Popz THE easy listening connoisseur. (Philip)
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