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Old 20th June 2013, 08:33 PM   #2411
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Yes it is Q8 fault. Maybe wrong orientation (pins), maybe base-emiter open circuit.
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Old 20th June 2013, 11:02 PM   #2412
caglarm is offline caglarm  Turkey
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I think shematic is wrong..marked point should be disconnected.

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Old 20th June 2013, 11:45 PM   #2413
jaagut is offline jaagut  Philippines
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Quote:
Originally Posted by wiljj78 View Post
Bro... Consider also to double check pin orientation of MJE's 340/350 by meter, be sure you inserted correctly, this is one of the case if you have huge offset when inserted inverted pins one of your pre-drivers.
It happens to me in middle east MJE340 by ON semiconductor as per datasheet pins are ECB but in actual check by meter it’s BCE.
Good luck...
Regards,
Thanks Bro, I did what you told and sure the MJE340 Motorola make has BCE pins!

Issue resolved when I rotate the transistor 180 degrees.

DC offset has gone from 59V to -16mV.


I tested loading input with music, and it works!

Last edited by jaagut; 20th June 2013 at 11:53 PM.
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Old 20th June 2013, 11:56 PM   #2414
jaagut is offline jaagut  Philippines
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Quote:
Originally Posted by AndrewT View Post
If Onsemi state it is ecb and your version is bce then whether it has Onsemi on it or not, it cannot be Their To126 transistor.
My other transistor in this setup was MJE350 from OnSemi. When I tested, pins are ECB.
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Old 21st June 2013, 04:25 AM   #2415
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Default AX11 under....test!

Quote:
Originally Posted by caglarm View Post
I think shematic is wrong..marked point should be disconnected.

Click the image to open in full size.
Yes shematic in this point is wrong but pcb is o.k.
By the way this is shematic for AX11.
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File Type: jpg Apex AX11 mod SCH.JPG (153.9 KB, 1035 views)
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Old 21st June 2013, 10:34 PM   #2416
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Actually there is one more wrong dot - emitter of MPSA13 is not connected to GND.
I warned Apex on our local forum, so he gave corrected schematic.
Here it is:
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File Type: jpg Apex AX11SCH (1).jpg (79.5 KB, 944 views)
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Old 22nd June 2013, 12:44 PM   #2417
tinitus is offline tinitus  Europe
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things started to get messy, and very confusing
I removed a few posts

please try to keep it clean for now, thanks


moderation
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Old 23rd June 2013, 06:24 PM   #2418
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Hello apex sir i need to add NFB for ax-14 or no need
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Old 24th June 2013, 07:14 AM   #2419
joeyt is offline joeyt  Philippines
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hello sir apex,
what is the possible substitute of bd 139, bc639 and bc640 for ax11, i cannot find this transistor here in our place.
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Old 24th June 2013, 08:35 AM   #2420
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2SC2383, 2SA1013 instead BC639, BC640 and 2SB649, 2SD669 instead BD139, BD140.
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