What the heck is this schematic symbol

[Harry Klippton]

 

[Nostradoomus]

 

[ThatDude]

They are Transistors. If you squint you can kind of make out that the component labels start with "Q".

 

[Cybercow]

Aren't those just typical representations common emitter amplifier circuits?

 

[Robert]

They have a few different names and acronyms but I've always called them digital transistors.

It's exactly what it looks like, a transistor with built-in resistors.

 

[Harry Klippton]

They have a few different names and acronyms but I've always called them digital transistors.

It's exactly what it looks like, a transistor with built-in resistors.

Thanks. The datasheet was in Japanese so I decided to stupidly ask here instead.

They're all connected in some kind of array (?) that I don't understand, and they may or may not have anything to do with the problem at hand, but they're connected to the LED that is lit that should not be.

 

[Robert]

What's the rest of the schematic look like?

 

[Harry Klippton]

What's the rest of the schematic look like?

I'll post it later when I can get on my computer. Its multiple pages but I probably don't have to tell you it's for a tascam

 

[jwin615]

4bit logic?

 

[Harry Klippton]

Hopefully this works. D510 (page 1, circled in red) is only supposed to illuminate when Rec SW (page 2) and either record function switch (also page 2) are closed, but instead it is illuminated all the time. I have two machines in this state.

 

[jwin615]

Those "digital" transistors are essentially pre biased BJTs. Easy drop in switches. I would wholly suspect Q507.
Maybe one of the internal resistors opened/shorted/drifted.
Edit. Possibly when someone plugged it into a 64 volt AC supply lol

 

[jwin615]

Does that pin on J509 change state when it should?

 

[jwin615]

I missed that switching logic
I need to get on desktop. I can't do this maze schematic shit on mobile.

 

[Harry Klippton]

I missed that switching logic
I need to get on desktop. I can't do this maze schematic shit on mobile.

It's rough for sure

 

[Harry Klippton]

Does that pin on J509 change state when it should?

Sorry, how would I test this?