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Old 21st January 2006, 04:27 PM   #1
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Default replacing the M250 transistors

hi everyone

im trying to replace the output transistor of the design M250.. i will be using 2SA1302 an 2SC3281 instead of (MJI5024 and MJI1525)..also the output driver.. i will use C2344 and A1011 instead of (MJE1531 andMJE1530)...
i need your suggestion guys if it has an error in replacingthis transistors..
tnx a lot..

ryan jan
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Old 21st January 2006, 04:53 PM   #2
Netlist is offline Netlist  Belgium
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Jan,
The original transistors should be easily available.
From memory, the proposed replacements aren't the best choice.

/Hugo
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Old 21st January 2006, 05:10 PM   #3
MikeB is offline MikeB  Germany
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Replacing transistors in an existing design with faster ones can cause instability, also 2SA1302 and 2SC3281 are mostly fakes as they are no longer in production from Toshiba. MJE15030/31 and MJ15024/25 are very good transistors.
Why do you want to replace them ? Availability ?

Mike
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Old 21st January 2006, 06:42 PM   #4
Eva is offline Eva  Spain
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Avoid 2SA1302 and 2SC3281. Not only they will be fakes, but you will have a very hard time mounting a TO-264 plastic case in place of a TO-3 metal-can case. (If you insist in using Toshiba, go for the newer 2SA1943 and 2SC5200 models.)

Despite their age, MJ1502x from On-Semi (Motorola) should be readily available as they are still industry-standard devices widely employed in audio power amplifiers. A better replacement may be the MJ2119x series, also from On-Semi. (Check also MJL1302 and MJL3281 if you want plastic cases).
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Old 23rd January 2006, 10:39 AM   #5
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Default thanx guyzz!!

I planned to use 2SA1302 and 2SC3281 in 5 pairs all(10 all). and i am using it now for 2pairs only(for testing) and it seems their is something not good.. yes your correct mike..i forced to use it because its the only available. Is 2SA1943 and 2SC5200 also ok eva? the heatsink i used is designed and drill for this (2SA1302 and 2SC3281) transistors only thats why i am looking for good transitors that could fit into my heatsink and somelike the replacement of real M250 transistors..is there any available transistors that looks like 2SA and 2SC that could use for M250?.. i found that the real output transistors are different.
Thank you for the suggestions and comment guyz..

i also found out that there are so many fake with regards to 2SA1302 and 2SC3281.. but the one i used was bought by my father 5years ago..

By the way, can i chane the LED into zener diode?..i hav a 2.7-3.0volts available..

ryan jan..
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Old 24th January 2006, 04:38 AM   #6
Eva is offline Eva  Spain
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2SA1943 and 2SC5200 were the new improved models that Thoshiba brought up when they discontinued 2SA1302 and 2SC3281 (I think it was in 1999), so they should work fine in place of the old devices.

MJL3281 and MJL1302 are custom versions of the old 2SA1302 and 2SC3281 made by On-Semiconductor and coming in the same package, their specifications differ a bit from those of the original devices (mostly due higher capacitances at the expense of better SOA), but they may be also good replacements.

Be careful because you may easily stumble into fakes of any of these models. Even the 2SA1302 and 2SC3281 bought 5 years ago could be fakes because they were already discontinued by that time, altough the fake market was not as big as nowadays.
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Old 24th January 2006, 06:18 AM   #7
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Hi everyone..

Do 2SA1943 and 2SC5200 are in production from Toshiba presently or they were also obsolete...like 2SA1302 and 2SC3281...

regards,
K a n w a r
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Old 24th January 2006, 07:39 PM   #8
Eva is offline Eva  Spain
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They are currently in production, I think.
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Old 26th January 2006, 09:21 AM   #9
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Default guyzz!!

hey guyzz another replacing transistors to schematic diagram i got from here.. i plan to replace the 2N5401 and 2n5550 at the 2nd stage transistors into MJE340 and MJE350..it seems that transistors from 1st stage is the same from the 2nd stage.. Will it be ok if i replace it?..i got this design from here together with M250 and i use these two in our soundworks..
i need your suggestion guyzz...
Thank you..

Ryan Jan
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Old 26th January 2006, 10:11 AM   #10
Eva is offline Eva  Spain
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I would not recommend such a replacement, these models are quite different.
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