Toshiba C3421 "NPN" Transistor

[Xproject187]

6:00 AM 4/5/2010

I hope I've done this correctly? but I'm a total Noob to this forum, so excuse me if I didn't.
But after a fair search of this forum for the part in question, I found nothing! so I figured I might as well post about it.

While cleaning my car I removed My Amp. Sony eSupport - XM-405EQX - Model Home .
I heard a rattle comming from inside, so I quickly finished cleaning the car & brought the amp in the house to take a look.
I opened the back of the amp & a lil gizzmo fell out !

So I Googled the gizzmo & learnt it is a NPN Transistor made by Toshiba.
A YouTube crash corse on Transistors sent me searching for a C3421-Data-Sheet & the XM-405EQX Service-Manual.

Well I found em & attached linx to both, in hopes that it'll aid in getting me a lil direction as to questions I have about the NPN & buying a new one. I'll post thee exact questions a little later, cause I have to go to class rite now, but I really wanted to get this much past the mods & posted.

Hopefully these will help the next guy who's looking for em, so that he won't have to search as long & as hard as I did !

Sony XM-405EQX Service Manual:
**broken link removed** .

Toshiba C3421-Data-Sheet:
**broken link removed** .

Photos of what I'm workin with & where I'm at:
**broken link removed** .

 

[Hero999]

I found another Japanese transistor 2SC2238 which is sold by RS.

**broken link removed**
2SC2238 pdf, 2SC2238 description, 2SC2238 datasheets, 2SC2238 view ::: ALLDATASHEET :::

 

[Xproject187]

I found another Japanese transistor 2SC2238 which is sold by RS.

**broken link removed**
2SC2238 pdf, 2SC2238 description, 2SC2238 datasheets, 2SC2238 view ::: ALLDATASHEET :::

I've got to leave in like 15 mins, & I wasn't going to post my questions till I got back from class, but basically I need to know the following:

Is there an interchange list or a cross reference that will help the guy at Radio Shack here in Modesto Ca. locate a transistor that Radio Shack sells which would work "as good if not better" than the C3421 in my Sony?
Is such a thing possible?
Or is that what you were saying in your reply?

Thanx for the quick reply!

 

[Hero999]

No, RS components, not RadioShaft, see the link I posted.

I just searched for a transistor rated to >120V, >1A with a similar Hfe and GBWP on the RS components website.

 

[Xproject187]

Thanks for the link in your post.
Surely most guy's who come here know how to use that site & would of went there straight away. However I don't.

Which is why I'm asking for guidance in finding the rite or interchangeable part.

I was hoping that someone @ this forum would take a look at the transistors radio shack has in their inventory & select one I could go in and buy, bring home & solder it into place.


I realize some of you may feel that I'm asking for someone to do My homework for me, but I know nothing of electronics & I'm overwhelmed, so for me to try learn how to find the rite part, is way too deep.

I respect the time it has taken all of you to learn your trade & I don't even begin to act as if I know anything about it, however I thought I could just pick up a part & re-solder it back into place & be good to go.

PS: I found another Sony amp it's bigger but it's broken, it has a transistor in it with the the code C3423 Printed on the front of it.
Is it too powerful to use as a alternative ?

 

[Hero999]

Some transistors have the part number abbreviated, the full part number is 2SC3421.

I doubt you'll be able to buy it from RadioShack who don't sell many components these days. You should go somewhere like RS Components, in the US you have Digikey.

I had a quick search of Digikey and found the 2SC59930Q.

Digi-Key - 2SC59930Q-ND (Manufacturer - 2SC59930Q)

 

[Xproject187]

Follow-up question on 2SC3423

Hero999 :
Thank's for your insight & for providing me with a direct link to the part I need at digikey.
But since I dont have a credit card I'm kinda locked out of that option.

I came across a Toshiba "2SC3423" (I've attached a Pic & Data Sheet).
I was hoping you'd tell me whether it will surfice as a replacement to the "2SC3421"
(As long as it's a good working part).
Also:
Will it deliver too much power ? or
Will it only deliver whats asked of it ? (Although capable of supplying more).

 

[Hero999]

What do you think?

Have you compared the two datasheets?

What are the similarities and differences?

 

[Xproject187]

2SC3423 as a replacement for 2SC3421

I'm probably wrong, but I think I see quite a few differences, & although I'm sure you don't need me to, I took the liberty of listing them below. However back to my Uneducated guess.

I can tell You that I really don't know, but if I was stranded on the moon & My rocketship needed a 2SC3421 but all I had was a 2SC3423 then I'd definitely want to give the 2SC3423 a try.

Because from what I can see it looks like it will do the same job with less overhead less overheating less stress on the part.
But in all ernest, I really don't know & it would only be a guess!


2SC3421 Complementary to 2SA1358

2SC3423 Complementary to 2SA1360
------------------------------------------------------

2SC3421 Suitable for driver of 60 to 80 watts audio amplifier
• High breakdown voltage


2SC3423 Small collector output capacitance: Cob = 1.8 pF (type.)
• High transition frequency: fT = 200 MHz (type.)
------------------------------------------------------

2SC3421 Collector-base voltage VCBO 120 V

2SC3423 Collector-base voltage VCBO 150 V
------------------------------------------------------

2SC3421 Collector current IC 1 A

2SC3423 Collector current IC 50 mA
------------------------------------------------------

2SC3421 Base current IB 100 mA

2SC3423 Base current IB 5 mA
------------------------------------------------------

2SC3421 Collector power Ta = 25°C 1.5
Dissipation Tc = 25°C PC 10 W


2SC3423 Collector power Ta = 25°C 1.2
Dissipation Tc = 25°C PC 5 W
------------------------------------------------------

2SC3421 Collector cut-off current ICBO VCB = 120 V, IE = 0 ? ? 100 nA

2SC3423 Collector cut-off current ICBO VCB = 150 V, IE = 0 ? ? 0.1 µA
------------------------------------------------------

2SC3421 Emitter cut-off current IEBO VEB = 5 V, IC = 0 ? ? 100 nA

2SC3423 Emitter cut-off current IEBO VEB = 5 V, IC = 0 ? ? 0.1 µA
------------------------------------------------------

2SC3421 Collector-emitter breakdown voltage V (BR) CEO IC = 10 mA, IB = 0 120 ? ? V

2SC3423 NOTHING LISTED FOR THIS CATAGORY
------------------------------------------------------

2SC3421 DC current gain hFE VCE = 5 V, IC = 100 mA 80 ? 240
(Note)


2SC3423 DC current gain hFE VCE = 5 V, IC = 10 mA 80 ? 240
(Note)
------------------------------------------------------

2SC3421 Collector-emitter saturation voltage VCE (sat) IC = 500 mA, IB = 50 mA ? 0.30 1.0 V

2SC3423 Collector-emitter saturation voltage VCE (sat) IC = 10 mA, IB = 1 mA ? ? 1.0 V
------------------------------------------------------

2SC3421 Base-emitter voltage VBE VCE = 5 V, IC = 500 mA ? 0.78 1.0 V

2SC3423 Base-emitter voltage VBE VCE = 5 V, IC = 10 mA ? ? 0.8 V
------------------------------------------------------

2SC3421 Transition frequency fT VCE = 5 V, IC = 100 mA ? 120 ? MHz

2SC3423 Transition frequency fT VCE = 5 V, IC = 10 mA ? 200 ? MHz
------------------------------------------------------

2SC3421 Collector output capacitance Cob VCB = 10 V, IE = 0, f = 1 MHz ? 15 ? pF

2SC3423 Collector output capacitance Cob VCB = 10 V, IE = 0, f = 1 MHz ? 1.8 ? pF
------------------------------------------------------

 

[Hero999]

The maximum collector current is to low, you ned a transistor which can at least take an Amp.

The other ratings are fine, the voltages are the maximum ratings, you can use the transistor at a lower voltage.

The Hfe (gain, the current amplification factor) is the same, in general, you can substitute with a slightly higher gain but it shouldn't be lower.

The transition frequency is, the frequency when the gain falls to zero, normally you can substitute with a higher frequency but not lower, although in this case it's only an audio amplifier which needs to amplify up to 20kHz so 120MHz is overkill and it's fine to use a slightly lower value. If this was an RF amplifier or the transistor was a much lower frequency then it would mater.

The capacitances are parasitics which only mater at high frequencies, a higher frequency transistor will generally have a lower capacitance.

 

[Xproject187]

Last ditch effort

If I could somehow push my level of frustration through these keys & onto my post.
This forum would straight Pop a Transistor!
I've been to quite a few local businesses that I thought might have the part, in an effort to locate a replacement, "Nill"
The way I see it I had 4 options.

#1.Find a way to buy the part with a Credit Card
(which I can't see happening)

#2.Find one at Radio Shack that'll work.
(Which I finally found out, the biggest they carry will handle no more than 75% of an Amp)

#3.Find one at a local electronics repair shop.
(Which I've had no luck at so far.)

#4.Find one inside the Sony 1000 Watt amp, that I have here for spare parts!
(Which by my inspection of their spec sheets comes out to none, & that I do not understand. I mean how can a amp twice as powerful not have a transistor in it that can handle half the job it was designed for?)

Please tell me I'm wrong

2SA1360

2SA1358

 

[Hero999]

Neither the 2SA1360 nor the 2SA1358 will do, I'm not going to go through it again, look at the datasheets and you should be able to now see why. I explained how to you how to do this before, if you didn't understand anything I said in my previous post then do ask.

Why don't you get a debit card?

#1 There are two possible solutions:

Most banks will do that, if your credit rating isn't high enough. I don't have a credit card either. I shop online with my debit card.

Ask a friend or family member, with a credit/debit card to to buy it for you and you pay them back.

#2 Not likely
RadioShack are useless when it comes to components.

#3 Not likely
Most electronics repair shops when out of business when cheap imports made most electronic items cheaper to replace than repair. This is why it's often hard to get spares - the Internet is the best place to look.

#4 It's possible.
Lots of smaller transistors can be connected in parallel to make a larger transistor. The chances are though, that the power transistors will be mounted to a heat sink which could be off the PCB.

 

[Xproject187]

Well thanks for your efforts & patience.

It's just I really thought I'd be able to use a part out of that scraped Sony 1000 watt amp. But clearly I won't have room if they're used in parallel, & from what I'm seeing thats exactly what Sony did. All along the front side are multiple transistors paired up I think it's called Darlington.
Ok later .

 

[Nigel Goodwin]

The normal courxe of action would be to obtain them as spare parts from Sony, it might be more expensive, but at least you know they are right.

You also need to ensure you replace everything that's faulty, replacing just the output transistors often causes them to blow again - as you haven't cured what caused them to blow in the first place.

 

[shokjok]

debit card parts purchase

Why don't you get a debit card?

#1 There are two possible solutions:

Most banks will do that, if your credit rating isn't high enough. I don't have a credit card either. I shop online with my debit card.

Ask a friend or family member, with a credit/debit card to to buy it for you and you pay them back.


Have you used a debit card in another country? Some of the American merchants I perused look for an expiry date, just like a credit card, or issuance by an American bank. My Canadian debit cards have been rejected by American merchants in person, so far not tried online. I had to resort to currency or travellers' cheques.

 

[Hero999]

The original poster lives in the US.

Why not just buy from Canadian suppliers?

Other people here from Canada don't seem to have a problem getting hold of most parts.

 

[mel8030]

an easy way to find a replacement is to use NTE. They usually cost more than a none NTE number.
http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf/$$Search


NTE373.

 

[Pedro English]

From somebody whose been in the service game for longer than I wish to remember........
Faced with your dilemma, I would install that transistor.
It is of the same general type, most likely a driver. The current used will most likely to be well inside the max rating, voltage ratings are similar.
Power up briefly, initially, and then check for any sighs of overheating. Massive overheating indicates a fault nearby e.g. other devices.
If it works ok, congratulations youve just fixed it!

 

[tvtech]

The normal courxe of action would be to obtain them as spare parts from Sony, it might be more expensive, but at least you know they are right.

You also need to ensure you replace everything that's faulty, replacing just the output transistors often causes them to blow again - as you haven't cured what caused them to blow in the first place.

That's what I tell my people when they are trying to repair a TV with a blown Line Output Transistor

A LOT always blows for a reason. Loptx going faulty, flyback caps gone low, flyback caps dry jointed, PSU running too high, line driver stage smoothing caps gone bad and, lately, LOT becomes loosely attached to it's heatsink over time due to poor thermal coupling by the cheap and nasty approach by Chinese manufacturers to use nuts without spring washers....

Every time a LOT blows there is a reason behind it. Gotta find the reason first otherwise you will blow up heaps of LOT's trying to fix the set.