Transistor Id

glen65 · 3rd March 2006, 10:10 PM

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 · 3rd March 2006, 10:12 PM

Here is another view

Tube_Dude · 3rd March 2006, 10:18 PM

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

glen65 · 3rd March 2006, 10:51 PM

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 · 4th March 2006, 12:44 AM

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 · 4th March 2006, 01:09 AM

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 · 4th March 2006, 02:52 AM

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 · 4th March 2006, 03:14 AM

Quote:

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 · 4th March 2006, 03:31 AM

Can it be a 2sc107

try this link

http://www.datasheetarchive.com/sear...ExactDS=Starts

anatech · 4th March 2006, 02:35 PM

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/shortfo...tr_index8.html

-Chris

3rd March 2006, 10:18 PM	#3
Tube_Dude diyAudio Member Join Date: Mar 2002 Location: Aveiro-Portugal	I looks like a logic level switch ( a transistor with a base resistor )for to be driven by a logic signal... __________________ Jorge

4th March 2006, 03:31 AM	#9
diy guy diyAudio Member Join Date: Jun 2004 Location: nil	Transistor Can it be a 2sc107 try this link http://www.datasheetarchive.com/sear...ExactDS=Starts __________________ diy guy

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3rd March 2006, 10:51 PM	#4
glen65 diyAudio Member Join Date: Jun 2004 Location: mid Ohio USA	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.

4th March 2006, 12:44 AM	#5
clem_o diyAudio Member Join Date: Jun 2005 Location: Manila	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

4th March 2006, 01:09 AM	#6
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	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

4th March 2006, 02:52 AM	#7
glen65 diyAudio Member Join Date: Jun 2004 Location: mid Ohio USA	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

4th March 2006, 02:35 PM	#10
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	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/shortfo...tr_index8.html -Chris