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Sony Vfet Illustrated build guide
Sony Vfet Illustrated build guide
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Old 23rd April 2018, 08:48 PM   #521
Arye is offline Arye  Israel
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Old 25th April 2018, 12:26 AM   #522
ichiban is offline ichiban  United States
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Sony Vfet Illustrated build guide
Default Four 500 Ohm pots in second kit !

Quote:
Originally Posted by Rodeodave View Post
Yup, if you're using the fqp parts, you'll likely need the 1k pots to get to the higher/lower Vgs as compared to the Toshiba parts.

The VFETs are not matched across polarities (n,p), so yours will work fine.
The boards from my 1st kit are populated with the resistors, caps & pots, but have been languishing in the cellar for months.
Seeing this post got me to check the pots. Seems the store sent 500 Ohm pots with Fairchilds.
The second kit has Fairchilds with four 500 Ohm pots, no 5k Ohm pots!
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Old 7th May 2018, 03:36 AM   #523
jaab6 is offline jaab6  Canada
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I'm stuck in the phase :PART 4 INSTALLING VFETS AND ADJUSTMENT
I tried to raise the AC line to voltage ~ less than 5 seconds but each time the fuse blow up
I'm afraid to damage the vfet and I'm super stressed !
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Old 7th May 2018, 05:57 AM   #524
Zen Mod is online now Zen Mod  Serbia
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Sony Vfet Illustrated build guide
did you completed setting procedure without VFets in place ?
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Old 7th May 2018, 08:20 AM   #525
jaab6 is offline jaab6  Canada
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yes I did and the setting was fine
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Old 7th May 2018, 08:30 AM   #526
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Sony Vfet Illustrated build guide
then proceed as prescribed

if you're scared , put 5A fast fuses in rails
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Old 7th May 2018, 08:44 AM   #527
jaab6 is offline jaab6  Canada
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Ok i will try
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Old 10th May 2018, 04:19 PM   #528
sledwards12375 is offline sledwards12375  United States
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I have completed voltage measurements and attached the results. I am concerned that the rail voltages, G-T6/T8 (approx 33 Volts) are a bit too high. My transformer is a Toroidy with 22V secondaries. My wall voltage is 123V, which is higher than the 115V toroid design. I am using the universal PSU rectifier board with fast Schottky diodes. I changed P3/P4 to the recommended value of 1K for use with the Fairchild MOSFETS. I believe the 9V measurements shown in the results are due to the higher resistance of P3/P4.

I proceeded with biasing up the front end and was able to achieve 1.5V across R5 and R6, with a T18/Gnd output voltage around 0.1 to 0.3 volts. My question now is, should I proceed to installing the VFETS with the higher rail voltage or correct it? If I should need to lower it, how do I do so?

Steve
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Old 10th May 2018, 04:53 PM   #529
sledwards12375 is offline sledwards12375  United States
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Had a few errors in voltage table, have attached corrected one.
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Old 10th May 2018, 07:22 PM   #530
Dennis Hui is offline Dennis Hui  Canada
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Sony Vfet Illustrated build guide
Your 9V readings are from the 1K P3/P4 pots.

My guess is that the rail voltages will drop a bit with a load though may still
be higher than 28V. The IRFP240/IRFP9240 mosfets will run a bit hotter but I suspect
should not be a problem. If it ends up higher than you like, you can
burn a bit of voltage by increasing the resistance in the CRC supply,
but I personally would give it a go as-is.

Hopefully others will chime in as well.
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