[TriEmbed] Substitute transistor

[Carl Nobile]

Sorry for the late response.
So assuming that the transistor is actually a 2SB1238, the TIP30 looks like
a good match.
I would also like to mention that transistors don't just blow, it is
usually caused by something else like a bad cap. I see an electrolytic cap
in the photo, as I'm sure you know these can go bad all by themselves,
unlike the transistor, so check these caps out also or just replace them.
It's actually very difficult to tell if a cap is bad, as they get older the
internal resistance starts to drop which is not always easy to determine.
The bias' in the circuit will change increasing the current in a transistor.
~Carl

On Sat, Nov 27, 2021 at 7:37 AM Mike Lisanke via TriEmbed <
triembed at triembed.org> wrote:

> I know ppl who replace their furnace controller boards with substitutes
> from ebay... but reworking problems with your microwave Is gutsy! :-p
>
> On Fri, Nov 26, 2021 at 9:11 PM The MacDougals via TriEmbed <
> triembed at triembed.org> wrote:
>
>> My microwave display suddenly went very dim.  I opened it up and found a
>> discolored
>>
>> spot on a circuit board feeding the display (see attached image).  That
>> component is
>>
>> marked B1238, so I assume it is a 2SB1238, which is obsolete.
>>
>>
>>
>>
>> https://www.digikey.com/en/products/base-product/rohm-semiconductor/846/2SB1238/30307
>>
>> Medium power transistor( 80V, 0.7A) 2SB1189 / 2SB1238 Features 1) High
>> breakdown voltage, BVCEO= 80V, and high current, IC= 0.7A.
>>
>> 2) Complements the 2SD1767 / 2SD1859. Absolute maximum ratings (Ta=25C)
>> Parameter Symbol Limits Collector-base voltage VCBO −80 Collector-emitter
>> voltage VCEO −80 Emitter-base voltage VEB O −5 Collector current IC −0.7 C.
>>
>>
>>
>> Anyone want to help me find a replacement?
>>
>> I dug through my Dad’s stash of old electronics and found a TIP30B, which
>> looks like it might work.
>>
>>
>>
>>
>>
>> ---> Paul
>>
>>
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>
> --
> Best regards,  Mike
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-- 
--------------------------------------------------------------
Carl J. Nobile (Software Engineer/API Design)
carl.nobile at gmail.com
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