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.
Head Scratching?
#1 Head Scratching?
Sorry, I couldn't resist!
#2 Re: Head Scratching?
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?
Little known fact, coherent thought can destructively interfere with itself leaving no thought at all, that’s why I prefer incoherent thought.
#3 Re: Head Scratching?
+1
agree with Nick
you are misreading the pinout Ray
agree with Nick
you are misreading the pinout Ray
There's nowhere you can be that isn't where you're meant to be
#4 Re: Head Scratching?
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.
More head scratching required.
Sorry, I couldn't resist!
#5 Re: Head Scratching?
I think my head scratching is done, I believe I've identified the issue and will aim to apply a fix at the weekend.
Sorry, I couldn't resist!
#7 Re: Head Scratching?
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.
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)