2sa818 / 2sc1628 again.....sorry.

[anderslober]

Hello forum.....I need some advice on replacements for these tr's.

They are CBE and they are used as pre-drivers in an Onkyo tx 8500 mkII.

I have searched the forum......ksa1381/ksc3503 come up.......together with mje15031/32................

Can a guru recommend a good sub....thanks.

I dunno which one (or other) is the best for the application.

(The tr will have to be modified for CBE....)

 

[Hyperion]

KSA1381/KSC3503 are the best ones to use IMO if you are replacing 2SA818 / 2SC1628.

The KSA/KSC above are ECB - in your equipment are the 2SA/2SC (EBC) 'free standing' on a PCB or is there a heatsink associated with them?

If free standing it should be quite easy to mount in place of the originals, otherwise you might have difficulty.

The MJE's (BCE) will work but are overkill, and again pin layout different.

 

[anderslober]

ok.....the ksa1381/ksc3503............there is a heatsink in the fray.

I will look into it............

It may be easier to use the MJE's........?

 

[anderslober]

This is how I intend to mount the ksa1381(ecb). The right tr is an mje15033.

2sa818(ebc) = ksa1381(ecb)
2sa968(bce) = mje15033(bce)

Both originals were blown.

If anybody sees anything wrong...let me know......

 

[anderslober]

here is a resistor (r35) that was close by.......

470 ohm / 1/2 w.

it measured 32 ohm...............

 

[ryuuoh]

Looks good!

 

[anderslober]

I am just wondering....these heatsinks have no mica or anything..........they are just 'bolted' to the heat sink..............

The heat sink doesn't contact any other metal.............so, I guess its ok...?

 

[Hyperion]

I am just wondering....these heatsinks have no mica or anything..........they are just 'bolted' to the heat sink..............

The heat sink doesn't contact any other metal.............so, I guess its ok...?

Should be OK - however in the absence of any insulation, any transistor (with an exposed metal tab) bolted to the heatsink will connect the collectors of those transistors together via the heatsink - watch for this.

Oh and don't forget the heatsink compound - you still need it - it is for heat transfer not insulation.

 

[anderslober]

ok...thanks........I think the collectors are meant to be connected.......the originals had their bare metal on the heatsinks......no mica or compound.......I will double check............

 

[anderslober]

Here is a picture of the scat'............Q09/Q11 and Q10/Q12.......it looks like the collectors are connected.

Can someone confirm....just so I don't do som'ink' real dumb!

 

[FootFungus]

So long as the collector leg of the transistor goes to the PCB you are ok. The problem case is where the collector leg is cut, and the metal tab is used instead as the collector point.

Make sure you get D grades of both the KSC3503 and A1381. The E grade was discontinued and a few places still have both D and E of the A1381.

 

[deltalight]

I have the same issue with anderslober. I am working on a Yamaha CR1020 driver board that has a 2SC1628 mounted on an isolated heatsink. The 2SC1628 has a ebc pinout whereas the MJE15030 and KSC3503 have pinouts of bce and ecb respectively. Also, the T0-202 pkg of the 2SC1628 and 2SA818 do not have a tab that is flush with the back side as with a T0-220, T0-126. I think I can modify the heatsink to accept the T0-126 or T0-220 pkg, but what is the standard procedure for correcting the different pinout?? The only thing I can think of is to perform surgery on the PCB by cutting traces and using wire jumpers.....

Any other suggestions???? :saywhat:

 

[TouchSpark]

Well here I am in 2026 looking for replacements for the old 2SA818/2SC1628 pair...Again.
It used to be replaced with KSA1381/KSC3503 but those seem to be EOL?
Then I looked to see if I could use KSA940TU/KSC2073 but those are EOL also?
Now I am trying to see what folks are using these days, It looks like the MJE15030/MJE15031 pair might work but not sure.

 

[Warren-Oates]

I would flap over to ebay and buy the preferred part from Peace Luv Music. I am not associated with the seller, but I have bought there when I need certain parts.