Yamaha C-1 Preamp - Phono Section Problem

After reading up in the service manual it looks like it's the last 3 letters on the 3rd row that makes the difference...not sure what the middle row identifies.

2SK78
5Y05
AEL

2SK78
0411
AEL

So both being "A" and "EL" is what's supposed to matter...the "A" are specified for that location and "EL" is listed as an acceptable suffix.

that's what I mean in my previoius post :thmbsp:
 
Small Update...

I decided to swap back just one of the 2SK78 to see if the issue would travel back to the other channel. This would determine if I need just (1) or (2) 2SK78 (A EL)

I swapped TR225 with TR226 and the problem went back to the Left Channel.

So, that's good news in that I only need (1) 2SK78 for the TR225/TR226 spot

The bad one was indeed the odd ball...

TR225
2SK78
5Y05
AEL

The other (3) good 2SK78 for TR226/TR221/TR222
2SK78
0411
AEL
 
Small Update...

I decided to swap back just one of the 2SK78 to see if the issue would travel back to the other channel. This would determine if I need just (1) or (2) 2SK78 (A EL)

I swapped TR225 with TR226 and the problem went back to the Left Channel.

So, that's good news in that I only need (1) 2SK78 for the TR225/TR226 spot

The bad one was indeed the odd ball...

TR225
2SK78
5Y05
AEL

The other (3) good 2SK78 for TR226/TR221/TR222
2SK78
0411
AEL
When you find good source of these transistors, I suggest to buy enough to replace all of them. Just keep them until you may need another swap. Also it will allow some kind of matching best pairs together.
 
Hello for_p1


When you find good source of these transistors, I suggest to buy enough to replace all of them.

don't you know that these VFET are no more availables since 30 years ?

I you have a good adresse let us know , we are many looking for it !
 
Except for a high-end Japanese audio company that went and made some for themselves...

http://www.hi-fiworld.co.uk/index.php/amplifiers/47-transistor/112-digital-do-main.html

digitaldomaindetailb1a2s.gif


http://www.6moons.com/audioreviews/firstwatt14/1.html
 
Hello

Sorry but I was one of the first to talk about digital domain on this forum and their SIT transistors are not usable in the C1 and worse in B1

Their B1B has nothing in common with The YAMAHA B1 except that the VFET made by YAMAHA were made in Hamamatsu too
 
Hello for_p1


When you find good source of these transistors, I suggest to buy enough to replace all of them.

don't you know that these VFET are no more availables since 30 years ?

I you have a good adresse let us know , we are many looking for it !
Right high voltage Jfets could be a tough call. When I worked on my C-2x I found two sources for Jfets used there. One was NOS, another newly made ones. Though Jfets used there had more common parameters.
 
Anyone heard from Patrice (clinic-audio)?

I've been waiting a couple months to get something finalized on the single vfet I need...he said he would help me but I haven't been able to reach him in a while after a few attempts. Anyone else have any suggestions? Patrice? You still there? Help please!
 
Hello
I am here yes , what VFET do you need ?2SK78 ?
I did send you one a long time ago don't you receive it ?
Send me PM , I will answer you as usual
 
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