2sb649/2sd669 replacement

[Oscar23]

Is there an available replacement 2sb649/2sd669 transistors can't seem to find an equivalent anywhere

 

[Oscar23]

Could i use Fairchild's KSA1220 and KSC2690

 

[redk9258]

They should.

 

[leesonic]

What is their purpose, and what kind of voltages are they running? You could get away with BD139/140 or BD237/238, as well as the 1220/2690 already mentioned. For example, if only doing lower voltage power supply regulation, the 139/140s might work.

Lee.

 

[FootFungus]

The KSA1220A and KSC2690A are the closest you can get without going off-brand.

 

[Oscar23]

Its for an optomica 5151 I found on the road it's stuck in protection

 

[FootFungus]

The rails are 55v. You should be fine with the KSA1220A and KSC2690A.

Are just the drivers shot? Or the outputs too?

 

[Oscar23]

Just the drivers the outputs are great

 

[FootFungus]

Hmm, that makes me think the 2SB649/2SD669 weren't quite strong enough. Are they mounted on the main heatsink?

 

[Oscar23]

No

 

[FootFungus]

If you can find them you might use the 2SA1837/2SC4793. They are a little beefier, but the pinout is reversed, so you'd have to orient them the reverse direction.

Alternatively, throw in the KSA1220A/KSC2690A and be done with it.

 

[Oscar23]

I found the 2SA1837/2SC4793 dijkey had them there to220 packages

 

[dlucy]

Running through the current devices available from Mouser (9/2017) my search yields KSB546 as a good replacement candidate for 2SB649 C (application for me is voltage regulation in Harman Kardon hk870 power supply at Q4).

Original device 2SB649 C

PNP
Power dissapation max Pcm 1W
Collector current max Icm -1.5A
Collector-base breakdown voltage V(br)cbo -180V
Collector-emitter breakdown voltage V(br)ceo -120V
Collector-emitter breakdown voltage V(br)ebo -5V
Transistion frequency fT 140 MHz
Package TO-126C
Pinout ECB
DC current gain hFE classification C 100-200​

My repacement choice KSB546 Y

PNP
Power dissapation max Pcm 25W
Collector current max Icm -2A
Collector-base breakdown voltage Vcbo -200V
Collector-emitter breakdown voltage Vceo -150V
Collector-emitter breakdown voltage Vebo -5V
Transistion frequency fT 5 MHz (I don't think this matters for voltage regulation)
Package TO-220 (means I can add a decent heatsink and avoid some of the overheating problem evident on PCB)
Pinout BCE (so I'll have to remember to turn the new transistor around)
DC current gain hFE classification Y 100-200​

 

[sonci]

I also have the same problem, the output transistors were also gone, the original were 2 SD1148\ 2SB863, I replaced them with NJW0281G/ NJW0302G,
The voltage rails should be around 60v and transistors are mounted on small heatsinks.
I was thinking about KSA1220A and KSC2690A, but I found that the originals maybe available on http://www.bdent.com/nsearch.html?catalog=yhst-864421581610834172249761&query=2sb649,
or are these just fakes same as those on ebay?

 

[tarior]

B+D is a reliable supplier.

 

[soundguy9]

Running through the current devices available from Mouser (9/2017) my search yields KSB546 as a good replacement candidate for 2SB649 C (application for me is voltage regulation in Harman Kardon hk870 power supply at Q4).

Original device 2SB649 C

PNP​

Power dissapation max Pcm 1W​

Collector current max Icm -1.5A​

Collector-base breakdown voltage V(br)cbo -180V​

Collector-emitter breakdown voltage V(br)ceo -120V​

Collector-emitter breakdown voltage V(br)ebo -5V​

Transistion frequency fT 140 MHz​

Package TO-126C​

Pinout ECB​

DC current gain hFE classification C 100-200​

My repacement choice KSB546 Y

PNP​

Power dissapation max Pcm 25W​

Collector current max Icm -2A​

Collector-base breakdown voltage Vcbo -200V​

Collector-emitter breakdown voltage Vceo -150V​

Collector-emitter breakdown voltage Vebo -5V​

Transistion frequency fT 5 MHz (I don't think this matters for voltage regulation)​

Package TO-220 (means I can add a decent heatsink and avoid some of the overheating problem evident on PCB)​

Pinout BCE (so I'll have to remember to turn the new transistor around)​

DC current gain hFE classification Y 100-200​

Hi, I was fixing a Luxman R-1120A, found and replaced a couple of bad EL caps, then decided to recap most of the boards. Anyhow, I was adjusting the idle currnet and it worked well. Turned off the unit and when removing one of the two clips it touched the standoff beside it and sparked. Now I can not adjust the dc offset and the unit is in protection mode. There is a high DC voltage on the speaker terminals (around 6v) and it slowly dissipates through the multimeter to less than 0.5V). I used to get 0 Volts.
I can not find a service manual with the board voltage markings. It is not easy to find substitue transistors as the replacements are also obsolete now.

2SB649A was a replacement for 2SB648A but even that is obsolete now.
Searching for an available and suitable sub, I came across the following: TTA004B, what are your thoughts on this?
Any suggestions as where I should be looking to troubleshoot would be greatly appreciated, thank you.

 

[Lp12C4A26]

On the subject of these replacements, they are the output devices in the Yamaha C-4 pre amp. Could they be replaced with Toshiba TTA/TTC004B transistors. Rail voltages are +-30. I have one of the originals with much higher gain than the other 3

 

[jheu02]

Ttc015,tta008 look to be a better match for the OEM transistors.

 

[Lp12C4A26]

Why? because of the higher transition frequency?

 

[jheu02]

Yes, more of the parameters of the OEM are met by these than the 004s.