switching power supply.. can't get -24v? - Page 10

BScorner · 4th March 2012, 07:30 PM

Quote:

Originally Posted by Zen Mod

wrong polarity , Bubba .

you need pair of 2SJ74BL

but - most important - you need either to little more learn basic electronic , or little more learn how to build strictly by the book ( if not in the mood for learning electronic)

Efff -- are you serious.. i got a matched pair of 2SJ74 in the datasheet photocopy under the lettering it also says 2SK170. Same fet?!

the writing on the fets is K170.

generg · 4th March 2012, 07:48 PM

one SJ109 can only be replaced by two SJ74 no SK170 possible, with SK170 the circuit cannot work....

BScorner · 4th March 2012, 07:55 PM

Quote:

Originally Posted by generg

one SJ109 can only be replaced by two SJ74 no SK170 possible, with SK170 the circuit cannot work....

wow.. really i did not know

generg · 4th March 2012, 08:38 PM

SJ types and SK types have (always) opposite polarity.....

You have a good chance your circuit will work when you replace the SK170!

Good luck!

AudioSan · 4th March 2012, 08:54 PM

Quote:

Originally Posted by BScorner

Efff -- are you serious.. i got a matched pair of 2SJ74 in the datasheet photocopy under the lettering it also says 2SK170. Same fet?!

the writing on the fets is K170.

have you maybe got matched pair of SJ74/SK170?
thats not the same.
you need 2 pair of matched SJ74. one pair pr ch.

BScorner · 6th March 2012, 08:11 AM

thanks guys used 74BL and works now... J09's were fake.

I have 2vdc offset on speaker output how do I lower this?

generg · 6th March 2012, 12:26 PM

Do you have the voltages over R7 and R8 mentioned in the scheme?

There can be different reasons......
Are your J74 a bit matched on Idss?

If you replace R7 by a pot of 1kOhm it might be possible to adjust the offset.

4th March 2012, 07:48 PM	#92
generg diyAudio Member Join Date: Jul 2009 Location: Near Frankfurt	one SJ109 can only be replaced by two SJ74 no SK170 possible, with SK170 the circuit cannot work.... __________________ and the First Wtt is......a really First Class PSS Idea !

4th March 2012, 08:38 PM	#94
generg diyAudio Member Join Date: Jul 2009 Location: Near Frankfurt	SJ types and SK types have (always) opposite polarity..... You have a good chance your circuit will work when you replace the SK170! Good luck! __________________ and the First Wtt is......a really First Class PSS Idea !

6th March 2012, 12:26 PM	#97
generg diyAudio Member Join Date: Jul 2009 Location: Near Frankfurt	Do you have the voltages over R7 and R8 mentioned in the scheme? There can be different reasons...... Are your J74 a bit matched on Idss? If you replace R7 by a pot of 1kOhm it might be possible to adjust the offset. __________________ and the First Wtt is......a really First Class PSS Idea !

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6th March 2012, 08:11 AM	#96
BScorner diyAudio Member Join Date: Feb 2012	thanks guys used 74BL and works now... J09's were fake. I have 2vdc offset on speaker output how do I lower this?

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