K1257 transistor datasheet needed.

jude · 2nd August 2002, 01:48 AM

Hey all.. I just searched for the fryed transisters on digikey and can't find any... the number is K1257.. My data manuals are nowhere to be found right now, so I was wondering if someone could give me a replacement number, or some info on these transisters...

thankyou.
Jude

jan.didden · 2nd August 2002, 05:41 AM

IF its a 2SK1257, which I suspect, see

www.semicon.panasonic.co.jp

Jan Didden

promitheus · 2nd August 2002, 05:59 AM

is it a FET or bjt ? Do you know?

promitheus · 2nd August 2002, 06:07 AM

2SK1257 N-FET 60 V 40 A 45 W 0.05 Ohm

jude · 2nd August 2002, 03:04 PM

whell.. it is in the power supply stage of my kenwood amp that is screwed.. It says K1257 then (m)30 then Japan.. that is it... there are two of them that I can't even read because they are too badly damaged, and two that are kind of allright.. on the pc board it says K1257..

the case is one of those little boxes with the tab on top and the tab is a connection.. forget what they call this type of case... It is a usual MOSFET case tho...

I am looking for replacements for these so I can see if I can get this amp fired back up..

Thankyou for your help...

Jude

tvi · 2nd August 2002, 03:17 PM

2SK1257 MATSUSHITA FET TO-220F US$5.55 At <a href="http://mcmelectronics.com/Search/search4-frame.jhtml?_DARGS=%2Fcommon%2Fprodsearchform.jhtm l">MCM Electronics</a>

Good Luck

Regards
James

jude · 2nd August 2002, 05:07 PM

oohh.. 6 bucks each... that was a little bit more than I wanted to spend... how exactally do I check capacitors and the other things like that.. If I spend 6 bucks a FET, I want to make sure they aren't going to go up in smoke..

thanx again..
Jude

tvi · 2nd August 2002, 05:52 PM

With big electrolytic capacitors I usually charge them up with my multimeter on Continuity/Diode test (about 3V), then swithh to Volts dc and watch them discharge slowly through the Multimeter.

The voltage should drop fairly smoothly, slowing down when it gets below about 1V.

Of course you will have to take them out of circuit.

For testing MOSFET see: <a href="http://www.4qd.co.uk/serv/mostest.html">MOSFET testing
</a>

<pre>IRFIZ48V N-ch 60V 39A 43W 0.012R TO220F</Pre>

Regards
James

jude · 12th August 2002, 06:22 PM

whell.. I figured out what was happening... I went out today and bought a digital multimeter cauz they were like 23 bucks on sale.. not bad... Brought it home, Popped a battery in it, and started testing my capasitors now that I have ordered the transistors... everything seemed normal.. I realized that I missed a bigger one.. it was a 3900MF 16V one at the corner of the board... I checked it.. the resistance started to climb as it charged... Good good.... then it stopped... I did not receve a reading of 1 (infinite).. BAD CAPACITOR!! I followed the traces to the K1257 with the chunks out of it.. It appeared that it was supposed to allow 12V high amperage to the scource of the MOSFET, then shut off.. the shutting off wasn't happening, so the chunks flew out of the transistor

.. gotta follow the traces thru the power supply now to check if anything else was damaged... lets hope not...

Whell.. thankyou for your help in finding the right replacement transistors...

Jude

peranders · 12th August 2002, 07:43 PM

Quote:

Originally posted by jude
I realized that I missed a bigger one.. it was a 3900MF 16V one at the corner of the board... I checked it.. the resistance started to climb as it charged... Good good.... then it stopped... I did not receve a reading of 1 (infinite).. BAD CAPACITOR!!

The resistance of an electrolythic capacitor can be 100kohm - more than 10 Mohms.

See my post in the end of the thread.

input caps - time to ask the experts

2nd August 2002, 01:48 AM	#1
jude diyAudio Member Join Date: Aug 2002 Location: canada	K1257 transistor datasheet needed. Hey all.. I just searched for the fryed transisters on digikey and can't find any... the number is K1257.. My data manuals are nowhere to be found right now, so I was wondering if someone could give me a replacement number, or some info on these transisters... thankyou. Jude

2nd August 2002, 05:41 AM	#2
jan.didden diyAudio Member Join Date: May 2002 Location: Great City of Turnhout, Belgium Blog Entries: 6	K1257 IF its a 2SK1257, which I suspect, see www.semicon.panasonic.co.jp Jan Didden

12th August 2002, 06:22 PM	#9
jude diyAudio Member Join Date: Aug 2002 Location: canada	UPDATE... whell.. I figured out what was happening... I went out today and bought a digital multimeter cauz they were like 23 bucks on sale.. not bad... Brought it home, Popped a battery in it, and started testing my capasitors now that I have ordered the transistors... everything seemed normal.. I realized that I missed a bigger one.. it was a 3900MF 16V one at the corner of the board... I checked it.. the resistance started to climb as it charged... Good good.... then it stopped... I did not receve a reading of 1 (infinite).. BAD CAPACITOR!! I followed the traces to the K1257 with the chunks out of it.. It appeared that it was supposed to allow 12V high amperage to the scource of the MOSFET, then shut off.. the shutting off wasn't happening, so the chunks flew out of the transistor .. gotta follow the traces thru the power supply now to check if anything else was damaged... lets hope not... Whell.. thankyou for your help in finding the right replacement transistors... Jude

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2nd August 2002, 05:59 AM	#3
promitheus diyAudio Member Join Date: Jan 2001 Location: Germany	is it a FET or bjt ? Do you know?

2nd August 2002, 06:07 AM	#4
promitheus diyAudio Member Join Date: Jan 2001 Location: Germany	2SK1257 N-FET 60 V 40 A 45 W 0.05 Ohm

2nd August 2002, 03:04 PM	#5
jude diyAudio Member Join Date: Aug 2002 Location: canada	whell.. it is in the power supply stage of my kenwood amp that is screwed.. It says K1257 then (m)30 then Japan.. that is it... there are two of them that I can't even read because they are too badly damaged, and two that are kind of allright.. on the pc board it says K1257.. the case is one of those little boxes with the tab on top and the tab is a connection.. forget what they call this type of case... It is a usual MOSFET case tho... I am looking for replacements for these so I can see if I can get this amp fired back up.. Thankyou for your help... Jude

2nd August 2002, 03:17 PM	#6
tvi diyAudio Member Join Date: Apr 2001 Location: Moonee Ponds, Vic, Australia	2SK1257 MATSUSHITA FET TO-220F US$5.55 At <a href="http://mcmelectronics.com/Search/search4-frame.jhtml?_DARGS=%2Fcommon%2Fprodsearchform.jhtm l">MCM Electronics</a> Good Luck Regards James

2nd August 2002, 05:07 PM	#7
jude diyAudio Member Join Date: Aug 2002 Location: canada	oohh.. 6 bucks each... that was a little bit more than I wanted to spend... how exactally do I check capacitors and the other things like that.. If I spend 6 bucks a FET, I want to make sure they aren't going to go up in smoke.. thanx again.. Jude

2nd August 2002, 05:52 PM	#8
tvi diyAudio Member Join Date: Apr 2001 Location: Moonee Ponds, Vic, Australia	With big electrolytic capacitors I usually charge them up with my multimeter on Continuity/Diode test (about 3V), then swithh to Volts dc and watch them discharge slowly through the Multimeter. The voltage should drop fairly smoothly, slowing down when it gets below about 1V. Of course you will have to take them out of circuit. For testing MOSFET see: <a href="http://www.4qd.co.uk/serv/mostest.html">MOSFET testing </a> <pre>IRFIZ48V N-ch 60V 39A 43W 0.012R TO220F</Pre> Regards James

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