2sb649a

[ChaosFlower]

This transistor is no longer available and most all on the net (ebay etc) are fakes. I think NTE 374 is the closest equivalent. Can someone experienced please confirm this is a good choice?

[petehall347]

Re: 2sb649a

180V, 1,5A, 140MHz

whats its job ?
p.s i wouldn't use nte unless desperate

[petehall347]

Re: 2sb649a

2SB649: KSA1220A or KSB546Y or TTA004B.

[R_J]

Re: 2sb649a

.

[redwire]

Re: 2sb649a

I second Toshiba 2SA1220 (Fairchild KSA1220) with a mid-range hFE. 2SA1209 is the NTE374 original.
2SA1381 is the higher voltage 300V AF driver but less current and power 7W.

[petehall347]

Re: 2sb649a

it all depends on the circuit really .

[ChaosFlower]

Re: 2sb649a

it all depends on the circuit really .

Well.. that's the problem.. I don't have the experience to know which parameters don't matter and which do. Some of the parameters of the KSA1220A are spot on, others vary.

The service manual is on this very site..

Transistor Q712

https://www.badcaps.net/forum/attach...2&d=1407703892

https://www.badcaps.net/forum/showth...light=NAD+C370

[petehall347]

Re: 2sb649a

regulator for -68v . is it shorted ?

[petehall347]

Re: 2sb649a

check out tip32a . haven't time to look right now

[eccerr0r]

Re: 2sb649a

Yeah looks like regulator, circuit seems to imply that you only need to match physical constraints, voltage differential constraints, and current flow capacity; most transistors should work fine. I'd agree a very inexpensive tip32 series would be an "overkill" if it will fit there (TO-220 is bigger than TO-126) but probably would be more comfortable with a TIP32C with its 100V rating to get a bit more voltage margin.

Also keep in mind that the pinout is "backwards" so if you need to attach to a heatsink, TIP32C won't work unless you face it in the "wrong" direction. I personally would try to jury rig it to fit at least, not sure about others

[ChaosFlower]

Re: 2sb649a

regulator for -68v . is it shorted ?

yeah! that's the one! your eyes are good..

[ChaosFlower]

Re: 2sb649a

Yeah looks like regulator, circuit seems to imply that you only need to match physical constraints, voltage differential constraints, and current flow capacity; most transistors should work fine. I'd agree a very inexpensive tip32 series would be an "overkill" if it will fit there (TO-220 is bigger than TO-126) but probably would be more comfortable with a TIP32C with its 100V rating to get a bit more voltage margin.

Also keep in mind that the pinout is "backwards" so if you need to attach to a heatsink, TIP32C won't work unless you face it in the "wrong" direction. I personally would try to jury rig it to fit at least, not sure about others

Thank you to you both.
I have looked at datasheets for NTE374 and 2SB649A. Unless I am missing something they look identical. The only downside is it means an extra 15 quid delivery with farnell because it is special order (from US).

I guess I would rather replace like with like. But I am interested in knowing what parameters I can ignore.

Why does everyone seemingly hate NTE?

[petehall347]

Re: 2sb649a

order from RS next day free delivery

[petehall347]

Re: 2sb649a

NTE are rebadged transistors .

[budm]

Re: 2sb649a

Did you verify that Q713 and Fusible resistor R723 are still OK?
So is the 2SB349A shorted out or what?

[petehall347]

Re: 2sb649a

q713 d707 should be checked as well

[ChaosFlower]

Re: 2sb649a

Did you verify that Q713 and Fusible resistor R723 are still OK?
So is the 2SB349A shorted out or what?

I am going to go through this thread again. Look at all things recommended. All trannys recommended. And test. I'll be back.
Suffice to say yes, so far Q713 is shorted. R717 is cooked.

[petehall347]

Re: 2sb649a

keep looking and testing . looks like there will be more faults .