Need help identifying transistor C401w6 for Sony TC-105 reel to reel

Hello, I have a Sony TC-105 Reel to Reel. I have maintained it and have it working as expected however when you have the machine ON (not playing tapes and on both channels) it gives off some white noise. I understand this is expected of an old machine but I am using it to digitlize some old reel to reel tapes and I feel this is too much white noise for my tastes so I looked into which transistor/capacitor is making the noise.

I found introducing cold spray to the following transistor (see photo) made the noise louder or changed the noise a bit. I cannot find this transistor anywhere but have learned alot from the forum. The transistor is marked (see photo) C401 w6.

I assume this is a 2SC401 transistor but i do not see this on the wiring diagram. If anyone can confirm this and suggest to me an alternative transistor that will work for this application.

I’ve attached the photos and even the wiring diagram for this.

Thanks in advance

tc-105 (1).pdf (1.7 MB)

Welcome to the Technical Forum. You are correct and it would be the 2SC401. I could not find a great replacement. I found the BC63916-D74ZCT-ND on this link:

What I do not like about this option is the gain is only 100 @ 150mA, 2V. It is listed as half of what the original part is. It is the closest I can find. Sorry. With the type of device this is, the gain is most likely needed.

Thanks for your reply. What does the ‘w6’ mean? Does it mean this could be the 2SC4016 instead of the 2SC401 transistor? I ask because there are other transistors on the board that are for example, C402w6 or C401w5. I assume the ‘w#’ has a meaning.

Most likley a date or lot code.

This might work as a cross as well. Please review the datasheet to see if it will work for your application.
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Thanks, it gives me a 404 error when I click the link though. Can you send it again?

Try this one:

Hi nx309,

2SC401 (on board) seems to be compatible with 2SC402 (shown on schematics). I cannot see anything special in the data, except that they are classified as RF transistors. From the photo can tell that the transistor’s terminals are quite corroded. That’s perhaps why you are getting “rusty” sound. Try first to resolder the transistor.
I’d say it is quite safe to replace the 2SC401 with a more modern audio NPN transistor (some people vote 2SC1815L, which is actually used commonly in pro audio, such as guitar effect pedals).

heke, AsamaLab

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