Transistors - good replacement?

[Stuey]

Hi there,

I need to replace two complimentary pairs of 2SB1353E / 2SD2033E in a Marantz SR-50 power amp stage. They have the following specs:

Part Number = 2SB1353E
Manufacturer Name = ROHM
Description = Si PNP Power BJT
V(BR)CEO (V) = 120
I(C) Abs.(A) Collector Current = 1.5
Absolute Max. Power Diss. (W) = 1.8
h(FE) Min. Static Current Gain = 100
h(FE) Max. Current gain. = 200
@I(C) (A) (Test Condition) = 100m
@V(CE) (V) (Test Condition) = 5.0
f(T) Min. (Hz) Transition Freq = 50M
Package = TO-225var

Part Number = 2SD2033E
Manufacturer Name = ROHM
Description = Si NPN Power BJT
V(BR)CEO (V) = 120
I(C) Abs.(A) Collector Current = 1.5
Absolute Max. Power Diss. (W) = 1.8
h(FE) Min. Static Current Gain = 100
h(FE) Max. Current gain. = 200
@I(C) (A) (Test Condition) = 100m
@V(CE) (V) (Test Condition) = 5.0
Package = TO-225var

I was considering using a pair of 2SB649A / 2SD669A (reversed to match ECB) as follows:

Part Number = 2SB649AB
Manufacturer Name = Hitachi Semiconductor
Description = Si PNP Power BJT
V(BR)CEO (V) = 160
V(BR)CBO (V) = 180
I(C) Abs.(A) Collector Current = 1.5
Absolute Max. Power Diss. (W) = 20
I(CBO) Max. (A) = 10u
h(FE) Min. Static Current Gain = 60
h(FE) Max. Current gain. = 120
@I(C) (A) (Test Condition) = 150m
@V(CE) (V) (Test Condition) = 5.0
f(T) Min. (Hz) Transition Freq = 140M
Status = Discontinued
Package = TO-126

The 669 has similar specs.

Will these do the job? I'm new to all this.

Thanks

Mark

[AndrewT]

Hi,
the 649/669 is available in A voltage rating (Vce0=160V) or standard rating (Vce0=120V)

Do you need the 160V rating?
The SOAR upto 120Vce is identical for both voltage types.

The advantage of the 120Vce0 standard type is that it is available in three gain grades b, c & d.
Gain grade c (hFE 100 to 200) matches your old transistor and d grade is even better.

You may find it easier to get 649c or 649d if you cannot find 649ac. Similar for 669.

[Stuey]

Thanks Andrew. I knew about the 120Vce0 version, but my local supplier only stocks the 160. I'm not sure of the gain grade.

I'm assuming any would be sufficient, then, but some versions better?

Thanks again

Mark

[AndrewT]

Hi,
the B in 649AB is the gain grade.

If your amp is susceptable to variations in hFE then that could make these low gain devices a poor substitute.

Try to get better than hFE=100.

649AC or 649C or 649D all match or exceed the originals.

There are many other transistors that can do the job but you have to compare the SOAR and Vce and fT and hFE to find a matching substitute. Is Cob relevant? Is it a driver with an intervening current gain stage?

[Stuey]

Sorry Andrew, I wasn't clear. The above specs are off the net - my supplier just has 649A/669A in their lists (without the extra suffix). I'll contact them.

Thanks for your help.

Incidentally, the Marantz authorised service rep was very willing to supply the correct ones direct, but it's an eight week wait as one of the types is o/s. I was surprised at their willingness to provide them! In my experience they don't supply to non-authorised repairers.

Cheers

Mark

[matti6]

2SB1353E:
2SA1249, 2SB649, 2SB1086A

2SD2033E:
(2SC2690, 2SD1563, 2SD1684)
this is without warranty -) matti6

[Stuey]

Thanks Matti - I've already ordered the 2SB649AC + 2SD669AC combination. Hopefully all will be well!

Cheers

Stuey

[Stuey]

Hi guys,

Just a quick update to say that the 649/669 combo works fine. The amp is working well now. A fair bit of work was required, though...

http://www.diyaudio.com/forums/showt...13#post1167713

Thanks for the help

Stuey