Help me pls with B&K st-140

tony Ma · 27th March 2011, 07:37 PM

Hi there I need helps on my old B&K ST-140
Suddenly my power amp went dead and these are what I did already

Replacing each side with new 2sk135 and 2sj50
Replacing each side with new 2N3440 and 2N5416
Replacing each side with new 100uF/100V and 47uF power supply electrolytics (silmic elna)

but still the there is sound coming out. I did check the BIG capacitor and there is a current over there. After I plug in, there is about 63 V still store in cap.

Any one can help me? Any idea why this amp still dead?
I am suspecting my rectifier might have a problem.
I could not find any replacement yet for this one (FPI4020W)
FPI4020W pdf, FPI4020W description, FPI4020W datasheets, FPI4020W view ::: ALLDATASHEET :::

tony Ma · 28th March 2011, 02:06 AM

Any one can suggest me with PS replacement? I think I found the schematic
http://4.bp.blogspot.com/_WeC7--3HfT...1600/st140.jpg
Any one can help me with PS design using the tyrodial from this B&K? tks so much

tony Ma · 29th March 2011, 03:48 PM

any one can recommends repair in OC or LA area?

claudeb960 · 5th May 2012, 03:03 PM

I recently replaced a bridge rectifier in my B&K ST-140 - big improvement. Purchased from Parts Connexion:

Item Number: SEMI-68495
Description: 27A 600V IXYS FRED BRIDGE RECTIFIER VBE17-06NO7

This definitely works and is much faster than the stock rectifier.

Cheers.

27th March 2011, 07:37 PM	#1
tony Ma diyAudio Member Join Date: Feb 2011	Help me pls with B&K st-140 Hi there I need helps on my old B&K ST-140 Suddenly my power amp went dead and these are what I did already Replacing each side with new 2sk135 and 2sj50 Replacing each side with new 2N3440 and 2N5416 Replacing each side with new 100uF/100V and 47uF power supply electrolytics (silmic elna) but still the there is sound coming out. I did check the BIG capacitor and there is a current over there. After I plug in, there is about 63 V still store in cap. Any one can help me? Any idea why this amp still dead? I am suspecting my rectifier might have a problem. I could not find any replacement yet for this one (FPI4020W) FPI4020W pdf, FPI4020W description, FPI4020W datasheets, FPI4020W view ::: ALLDATASHEET :::

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28th March 2011, 02:06 AM	#2
tony Ma diyAudio Member Join Date: Feb 2011	Any one can suggest me with PS replacement? I think I found the schematic http://4.bp.blogspot.com/_WeC7--3HfT...1600/st140.jpg Any one can help me with PS design using the tyrodial from this B&K? tks so much

29th March 2011, 03:48 PM	#3
tony Ma diyAudio Member Join Date: Feb 2011	any one can recommends repair in OC or LA area?

5th May 2012, 03:03 PM	#4
claudeb960 diyAudio Member Join Date: Oct 2011 Location: Chicagoland	I recently replaced a bridge rectifier in my B&K ST-140 - big improvement. Purchased from Parts Connexion: Item Number: SEMI-68495 Description: 27A 600V IXYS FRED BRIDGE RECTIFIER VBE17-06NO7 This definitely works and is much faster than the stock rectifier. Cheers.