Transistor Id

[glen65]

I’ve been trying to find the info on this transistor but haven’t successful. It says C107 so I figured it might be a 2sc107 but no dice. It does have some odd readings when testing it. It may have built in resistors. It’s being used in a RCA 50 watt receiver made for Radio Shack. The model is STA3850. It’s being used on a small power supply board. I will post a couple of pics.

Any info appreciated.
thanks

 

[glen65]

Here is another view

 

[Tube_Dude]

I looks like a logic level switch ( a transistor with a base resistor )for to be driven by a logic signal...

 

[glen65]

Yes it does appear to be something along those lines.
I just havent been able to find any data on it so I can come up
with a replacement for it.

 

[clem_o]

If its used to logic-switch, it can't be too critical? Trace the circuit, figure its polarity and perhaps just replace with a generic transistor with a small resistor inserted in series with the base?

Cheers

 

[anatech]

Hi glen65,
It looks to be a DTC107 logic transistor I'm guessing. NPN. They are sometimes called an inverter. Clem is right, they are just a transistor with a pair of built in resistors.

A search pointed to Sony, Rohm made those series of parts. Measure the drops between B and C, E.

Is that for AC detect? Measure the voltages when the unit is on.

-Chris

 

[glen65]

Thanks for the response I was having trouble getting the receiver to power up. The standby light works ok. I pulled this transistor out to check it then put it back in and now the unit works. I suspect it could be an intermittent failure of the component.
That’s why I want to replace it.

thanks

 

[glen65]

A search pointed to Sony, Rohm made those series of parts. Measure the drops between B and C, E.

Is that for AC detect? Measure the voltages when the unit is on.

-Chris

B to E is 5.1 VDC
B to C is 4.5 VDC

If I remove the transistor the unit wont start. Press the power button once the standby led goes out. Press it again and the standby comes back on.

 

[diy guy]

Transistor

Can it be a 2sc107

try this link

http://www.datasheetarchive.com/search.php?q=2sc107&sType=part&ExactDS=Starts

 

[anatech]

Hi diy guy,
Wrong case for one, this one is much more modern for two.

The most important clue .... 5 VDC on the base indicates an internal resistor. This confirms it as a digital switch transistor. A funny Sony number no less. There are DTC transistors that will sub fine. It works on 5V, so look in the logic sections of older VCRs and cassette decks. You may find something suitable on a board. DTA is the other polarity.

Try this link for more information http://www.rohm.com/products/shortform/21trstr/trstr_index8.html

-Chris

 

[glen65]

Thanks ..I will check it out.
I will have to determine what the internal resistance
is. The list from rohm goes from 1 to 47 k.

 

[anatech]

Hi glen65,
Just measure the base - emitter resistance reverse biased.

-Chris

 

[clem_o]

Didn't realize they even make such things! Learn something everyday... Thanks Chris...

Cheers!

Clem

 

[anatech]

Hi Clem,
LOL

Don't ask how long they've been available. Tear some old stuff down and look for them. I won't tell!

Don't feel bad, most guys that get paid for servicing don't know what they are either!

-Chris