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Sony Vfet Illustrated build guide
Sony Vfet Illustrated build guide
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Old 15th May 2018, 01:19 AM   #541
nycavsr2000 is offline nycavsr2000  United States
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Sony Vfet Illustrated build guide
Got my answers from posts 3064-3070 on this thread:

Sony VFET Amplifier Part 2

Best,
Anand.
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Old 16th May 2018, 08:05 PM   #542
mr_whocares is offline mr_whocares  Germany
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Default GND connection

as I am slowly progressing with the amp and have now finished the PSU using 4pole caps I have a question regarding the GND connections:

is it better to use the audio ground (star GND at the PSU) for the speaker connections and connect only the "+ output" from the amp pcb, or use both the "GND and +output" on the amp pcb?
The same same question is also for wiring the input connections ;-)

best regards
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File Type: jpg amp übersicht.jpg (269.0 KB, 257 views)
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Old 18th May 2018, 01:58 PM   #543
mr_whocares is offline mr_whocares  Germany
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any advice to my above question? :-)
thanks and regards
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Old 18th May 2018, 02:40 PM   #544
Zen Mod is offline Zen Mod  Serbia
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Sony Vfet Illustrated build guide
look no further than on how Papa made it
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Old 18th May 2018, 04:44 PM   #545
mr_whocares is offline mr_whocares  Germany
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Quote:
Originally Posted by Zen Mod View Post
look no further than on how Papa made it
many thanks MZ! it means wiring the GND for input and ouput from the amp PCB and not from the audio star GND at the PSU?
regards
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Old 19th May 2018, 02:32 AM   #546
jaab6 is offline jaab6  Canada
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Sony Vfet Illustrated build guide
Hi,
I will report was happened, the right chanel is blowing fuse when I try the part 4 (after connection the vfet). The variac do a strange noise! I was thinking perhaps there is a short somewhere, I replace all the mica sheets from the vfet and the mosfet. I did again part3 without any problem but when i started the variac for part 4 the strange noise appear again and I stopped I didn't go further.

I tried in the left chanel, I did again part3 to be sure all was alright, it took time to stabilize r5 = 1.502 r6 = 1.502 and 18 = 0.0336 v. I start part4 and I got rigth away r32 = 101. and DC offset at the speaker terminal 0.0262 v I'm letting warm up before I will do any adjustments.

I don't know what to do in the right chanel!
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Old 19th May 2018, 04:47 AM   #547
jaab6 is offline jaab6  Canada
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oups a mistake with so many probes ! r32= 0.0262 DC offset = 0.101
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Old 19th May 2018, 02:54 PM   #548
Rodeodave is offline Rodeodave  Austria
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Sony Vfet Illustrated build guide
Honestly, at this point I would verify that your VFETs are still viable.

See attached diagrams. The gate voltage MUST be present before you apply any voltage across source-drain. Adjust gate voltage to start passing current though the VFET (mount to some kind of heatspreader), bonus points for measuring Vgs @ 0.5A Ids (which should correspond to the number written on your VFETs).
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Old 19th May 2018, 08:36 PM   #549
delecoy is offline delecoy  United States
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No variac for this build...could do more harm than good.

To be more clear: once the vfets are installed. Prior to that, OK.
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Old 19th May 2018, 08:46 PM   #550
Rodeodave is offline Rodeodave  Austria
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Sony Vfet Illustrated build guide
Good catch, delecoy.

Page 9 of the DIY Sony VFET article reads as follows:

"I suggest that you raise the AC line to voltage over a period of less than 5
seconds."

If you go too slow I think the gate bias which is supposed to turn off the VFETs isn't there, thus they'll conduct whatever is available.

Still, if it works for one channel, and doesn't for the other, I'd check that channel's VFETs.
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