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[SOLVED] SOT23 transistor Marked 93A

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me_guitarist

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Good day guys!

Does anyone know or seen before a sot23 transistor marked 93A?
I have a small sound amplifier using this part & has burn would like to replace it but couldn't know what the part is.

Could someone help?
Thanks in advance.
 

Possibly it's a DTA143TEB 'digital' transistor from Rohm. The package is a special one but the same shape and almost the same dimensions at SOT23.
It certainly isn't a BLY93A, that is an RF power transistor in a ceramic package with a mounting stud !

Brian.
 

betwixt said:
Possibly it's a DTA143TEB 'digital' transistor from Rohm. The package is a special one but the same shape and almost the same dimensions at SOT23.
It certainly isn't a BLY93A, that is an RF power transistor in a ceramic package with a mounting stud !

Brian.
Click to expand...
Hello Brian,

Thanks for yr input.
I check DTA143TEB datasheet before but the marking doesn't match. But if I try google it showing DTA143TEB marked 93.
Although I found a marking 91A, FMMT591A, but not sure its suitable. FMMT593 marked 593.

I tried replace with BC856B but the output are very slow & noisy.

Still trying.

Regards
 

Personally, I would always try to extract the respective circuit part (identifying the wiring with an ohmmeter and so on..) and understand, which part most likely can fit.

If a part is burnt, you also should try to understand the reason. In most cases, more parts are affected. The point also refers to analyzing the circuit.
 

Try BFR93A (many makers).
 

KJ6EAD said:
Try BFR93A (many makers).
Click to expand...

Unfortunately BFR93A transistors aren't marked 93A! NXT label it R2p for example, Infineon R2s. It is an unlikely transistor in an audio amplifier.

It could be the FMMT493ATA - that is actually marked 93A

Keith.
 

It could be the FMMT493ATA - that is actually marked 93A
Click to expand...
The first promising suggestion in this thread. Unfortunately I don't find a marking code in the most recent datasheet.
 

FvM said:
The first promising suggestion in this thread. Unfortunately I don't find a marking code in the most recent datasheet.
Click to expand...

Neither did I, but it is shown on Diodes Inc. web site as 93A marking:

It still may not be correct. It took some finding because BFR93A/BFT93A etc get in the way of searching.

Keith.
 

Thanks guys.

I'm sure it is a PNP transistor. It turned on by a BC846 from a MCU pin & output the sound thru a 470N capacitor to 1 of the loud speaker wire, another wire from speaker connected to GND.

I tried PDTA143 the sound are slow & higher current than the original transistor marked 93A.

I'll post here the schematic once I done it.
 
Last edited:

Attached the schematic for the circuit.
Pls correct me if I'm wrong on the schematic.

The burn out transistor is Q2.
R1 = 10K
R2 = 4K7
R4 = 11R
Q1 = BC846
Q3 = BC856
C1 = 470N

 

If the extracted circuit is correct so far, it must be a NPN transistor. But the amplifier would work in class B with considerable distortions. Is it expected to be linear?
 

FvM said:
If the extracted circuit is correct so far, it must be a NPN transistor. But the amplifier would work in class B with considerable distortions. Is it expected to be linear?
Click to expand...

I don't know about the circuit just doing some study & research how the amplifying works & accidentally damage the transistor Q2.

---------- Post added at 13:38 ---------- Previous post was at 13:34 ----------
keith1200rs said:
FMMT493ATA

Keith.
Click to expand...

hi Keith,

you were saying FMMT493A based on the circuit or the marking 93A?
As I can't see any marking note on the data sheet.
 
Last edited:

me_guitarist said:
hi Keith,

you were saying FMMT493A based on the circuit or the marking 93A?
Click to expand...

Both. It satisfies the likely requirement for an NPN in the circuit you posted and is the only SOT23 transistor I have found that is actually MARKED 93A (as opposed to having 93A in the name e.g. BFT93A).

Keith.
 

Hi Keith,

Thanks for yr fast respond.
I'll try to get a FMMT493A & have a try.
The Zetex data sheet din't noting the marking.
Any other brand beside Zetex?
By the way, the circuit operate from 9~60VDC.
 

Any transistor with similar specification should work as well. By the way, what kind of "audio" amplifier is it? A piezo sirene driver?
 

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