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Old 6th June 2016, 10:35 AM   #1
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Default yamaha b1 where are 2sk77?

hi i'm new of the forum, i live in italy and i have a b1, where i can find 2sk77 v-fet on the amplifier? some one can post a photo wear i can see where are fixed? thanks
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Old 6th June 2016, 10:43 AM   #2
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Do you mean B1 Clavinova? or BX1 amplifier?
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Old 6th June 2016, 12:16 PM   #3
ilimzn is offline ilimzn  Croatia
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Does the B1 clavinova or BX1 use 2SK77 VFETs? So obviously those are not being asked about!

Only source of 2SK77 is a B1 amplifier and (very) occasionally TaoBao but there are a lot of 'fakes', re-labelled 2SK180 from Tokin. SOME can be used as replacements, but it depends on tge grade, and in some cases the grade is not printed so it has to be verified on a curve tracer.
They are located on the main heatsink modules. Look here:
http://img.canuckaudiomart.com/uploa...yamaha_uc1.jpg
The 2SK77 are on the large heatsinks on the sides (2 per side). One on each heatsink (notice two screws for each heatsink, when unscrewed, the whole heatsink comes out, it is connected to the rest of the amplifier with a connector on the bottom).

More here:
http://www.audiofil.net/data/upload/...1_forum_37.jpg
and here:
http://www.audiofil.net/forum/printe....asp?TID=11596

Last edited by ilimzn; 6th June 2016 at 12:19 PM.
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Old 7th June 2016, 10:04 AM   #4
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Hi thanks ifound It But i'm Not able Take of for photo But tecnitian Said that nobody nevEr touch so i think are original thanks
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Old 7th June 2016, 03:23 PM   #5
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Originally Posted by alexpizz12 View Post
Hi thanks ifound It But i'm Not able Take of for photo But tecnitian Said that nobody nevEr touch so i think are original thanks
Each of the 4 V-FET modules is held in place by 2 screws. Take out the screws and the modules pull out of their plugin sockets with ease. When you put them back make sure you put the same module back in the same location it came from.

Be sure to discharge the power supplies before removing or installing the modules.
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Old 7th June 2016, 08:39 PM   #6
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Originally Posted by Yamahear View Post
Each of the 4 V-FET modules is held in place by 2 screws. Take out the screws and the modules pull out of their plugin sockets with ease. When you put them back make sure you put the same module back in the same location it came from.

Be sure to discharge the power supplies before removing or installing the modules.
Hi yes But how To discharge The Power? How i Can do It? Thanks
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Old 7th June 2016, 11:31 PM   #7
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Originally Posted by alexpizz12 View Post
Hi yes But how To discharge The Power? How i Can do It? Thanks
Stand the B-1 on its side and remove the bottom cover. You'll see the main power supply cap screws towards the front and centre. Connect one end of a 10 ohm 20 W or more resistor to the copper ground bar that commons the two dual caps and connect the other end to each of the four screws marked + and -. Keep the resistor connected to each screw for about 20 to 30 seconds.

To discharge the -200V take the top cover off and connect the resistor between the the two terminals of the large cap that's mounted at the rear of the chassis. I find the -200V discharges fairly quickly on its own.

Us a meter to be certain the caps are discharged.
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