Help needed with transistors 2SD147 and D313

PhantomBox · 18th August 2011, 02:07 PM

Hi there.
I got an AKAI X360DS reel (transistorized) from the 70s that quit its job. The (very old) motors suddenly won't start any more. In particular, one transistor in it gets extremely hot to the point when it smokes and is about to burst out in flames.
This transistor is an old 2SD147 (TO66, its like a small hat. TO3 is a big hat) and no more available. I found a D313 (TO220) as a replacement for it. Now, what would be the correct pinout of this 2SD147?
I think I might be able to adapt the D313 with a little advise.
BTW, a matching service manual isn't freely available on the internet.

StevenOH · 18th August 2011, 02:40 PM

2SD147 pinout.

PhantomBox · 18th August 2011, 02:46 PM

Thanks Steven.
I just found the same pinout in an old NTE bible. The one you just sent confirms mine.

wg_ski · 18th August 2011, 02:53 PM

TO-220 will sort of "plug into" a TO-66 socket. Trim the collector lead, and bend the base and emitter at 90 degrees - right where the leads change width. Connect the collector tab to the mounting hole with one of the screws from the TO-66. It will fit comfortably in *one way*, which is the correct one. The wrong way is too tight a fit.

A transistor getting too hot is usually just a symptom that something *else* is wrong. A transistor won't get hot unless it's actually *working*. It's a good idea to replace one that has been badly stressed, but if you don't find out why it will do it again.

PhantomBox · 18th August 2011, 03:03 PM

I know that. I'm still searching for a service manual or at least a schematic diagram. These early AKAI are kind of a PITA with all its soldered and hard to reach points.

Enzo · 18th August 2011, 11:39 PM

What if the transistor is getting hot because too much current is being dragged through it by a failure elsewhere?

I certainly have changed my share of motor run caps on reel deck motors over the years.

PhantomBox · 18th September 2011, 12:55 AM

Took some time but here I am again.

By "motor run caps" what do you exactly mean?

I checked the schematics (I got them now) and the caps for the power supply aren't that hard to find. Since chances are that the mechanisms of the motors (rubber bands, rubber transmission wheels and brakes) are dried out, I think that using the preamp of this reel deck could be quite interesting so I'd just need it to engage into REC mode.
Of cause I'll also have to change some caps on the preamp section.

18th August 2011, 02:07 PM	#1
PhantomBox diyAudio Member Join Date: Jan 2008	Help needed with transistors 2SD147 and D313 Hi there. I got an AKAI X360DS reel (transistorized) from the 70s that quit its job. The (very old) motors suddenly won't start any more. In particular, one transistor in it gets extremely hot to the point when it smokes and is about to burst out in flames. This transistor is an old 2SD147 (TO66, its like a small hat. TO3 is a big hat) and no more available. I found a D313 (TO220) as a replacement for it. Now, what would be the correct pinout of this 2SD147? I think I might be able to adapt the D313 with a little advise. BTW, a matching service manual isn't freely available on the internet.

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18th August 2011, 02:46 PM	#3
PhantomBox diyAudio Member Join Date: Jan 2008	Thanks Steven. I just found the same pinout in an old NTE bible. The one you just sent confirms mine.

18th August 2011, 02:53 PM	#4
wg_ski diyAudio Member Join Date: Oct 2007	TO-220 will sort of "plug into" a TO-66 socket. Trim the collector lead, and bend the base and emitter at 90 degrees - right where the leads change width. Connect the collector tab to the mounting hole with one of the screws from the TO-66. It will fit comfortably in one way, which is the correct one. The wrong way is too tight a fit. A transistor getting too hot is usually just a symptom that something else is wrong. A transistor won't get hot unless it's actually working. It's a good idea to replace one that has been badly stressed, but if you don't find out why it will do it again.

18th August 2011, 03:03 PM	#5
PhantomBox diyAudio Member Join Date: Jan 2008	I know that. I'm still searching for a service manual or at least a schematic diagram. These early AKAI are kind of a PITA with all its soldered and hard to reach points.

18th August 2011, 11:39 PM	#6
Enzo diyAudio Member Join Date: Sep 2004 Location: Lansing, Michigan	What if the transistor is getting hot because too much current is being dragged through it by a failure elsewhere? I certainly have changed my share of motor run caps on reel deck motors over the years.

18th September 2011, 12:55 AM	#7
PhantomBox diyAudio Member Join Date: Jan 2008	Took some time but here I am again. By "motor run caps" what do you exactly mean? I checked the schematics (I got them now) and the caps for the power supply aren't that hard to find. Since chances are that the mechanisms of the motors (rubber bands, rubber transmission wheels and brakes) are dried out, I think that using the preamp of this reel deck could be quite interesting so I'd just need it to engage into REC mode. Of cause I'll also have to change some caps on the preamp section.

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