Yamaha B-2 restoration journey

A small update here. Less time to spend on the B-2 as the girlfriend returned home after a 6 months lasting internship abroad. You know how it goes when the boss returns home :biggrin:

I had some time to re-mount the VFET's the proper way, with silicone (non conducting) thermal grease.



Also found a 'new' power switch, I actually stole it from my CT-600. I combined it with the well known Triac switch solution.

I also had to replace two components on the power board due to new insights. Replaced C222 with a PP film cap and TR216 with a new Zetex transistor.

And I installed some new CMC RCA sockets with new shielded wires for direct input in the driver boards. Again, the changes made are reversible.

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Next up: reinstall the driver boards as is and fire the B-2 op. Exciting :naughty:

Great work!

I am using similar RCA's. Love the style and sturdiness.
 
Yeah, that is why I just drilled holes and installed new ones. I would be impressed to see a pretty way of handling that task.
 
Nice. Can we see a picture of the input jack board and how you managed that?


I can't take a good pic, because the back panel is reinstalled already. But, my solution was really simple and did not involve any mutilations.

Because I went for the direct input and I will only use DC mode, I bypassed the input board completely, except for the meter section. So, I desoldered the small black board with the original RCA sockets and mounted the pcb in it's original place. I cut off and crimped the original wires, so they can be reinstated in the future.

Also due to the bypass option, I lost input selection (would never use that anyway). Hence the RCA's of Input 2 are not connected and act as dummies to fill up those chassis gaps. So the RCA's of Input 1 are directly wired with new screened wires to the driver boards.

I made these choices, because in my opinion it was the only way to combine these 'tweaks' with the reversibility of it.

Great work!

I am using similar RCA's. Love the style and sturdiness.

Yes they are great, I really like the construction of it. Especially the nut that goes on it from the back (input side). Tip: when you buy the CMC sockets, buy the $10 fasten tool with it. I bought these at HFC and they didn't mention the tool. Ended up scratching the nuts with pliers, even though I used cloth. So I ordered the tool and got 4 new nuts for free directly from CMC. Great customer service :thumbsup:
 
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Next up: reinstall the driver boards as is and fire the B-2 op. Exciting :naughty:


I meant to tell you...it looks like you have the inputs reversed. Left is usually White and Right is usually Red. It'll work either-way, just a matter of preference I guess.
 
I meant to tell you...it looks like you have the inputs reversed. Left is usually White and Right is usually Red. It'll work either-way, just a matter of preference I guess.

Yes I know, but I'm a bit of an autist / perfectionist. See this pic, maybe you can guess why I put the red RCA's on top :p

IMG_3711.JPG
 
yeah, can't blame you...dunnit myself once too for the same reason, but ended up regretting it 'cause later I was mixing the inputs. besides, your tops match but what abt the bottoms :rolleyes:
 
Yes I know, but I'm a bit of an autist / perfectionist. See this pic, maybe you can guess why I put the red RCA's on top :p

View attachment 884823

could you please tell me the distance between the back of the PSU board and the underside of the cover...I guess measuring to the back plate lip....that is if your unit is still with the hood off.
I ended up moving bunch of those power resistors to the back of the board...same for the trimmers..I guess I should have worried about the distance before :biggrin:
or I could measure the distance from another unit, but I am just lazy...crap, it looks like is gonna be close.
 
yeah, can't blame you...dunnit myself once too for the same reason, but ended up regretting it 'cause later I was mixing the inputs. besides, your tops match but what abt the bottoms :rolleyes:

Black and white are equal to me, but those redheads aren't :p

could you please tell me the distance between the back of the PSU board and the underside of the cover...I guess measuring to the back plate lip....that is if your unit is still with the hood off.
I ended up moving bunch of those power resistors to the back of the board...same for the trimmers..I guess I should have worried about the distance before :biggrin:
or I could measure the distance from another unit, but I am just lazy...crap, it looks like is gonna be close.

I'll measure when I'm back at it!
 
An (for me major) update here. I installed the driver boards as-is, wired the RCA's straight to them.

IMG_3700.JPG IMG_3701.JPG IMG_3702.JPG IMG_3703.JPG

After that I triple checked everything and went for the first power-up.

I was a bit nervous obviously.

IMG_3778.JPG

Dialed the bias pots fully CCW, hooked the meter on the +85 rail and fired it up....

Clang!

That was the relay, nice. +85 and -85 were 0,5 V off, adjusted them to +85.

IMG_3779.JPG IMG_3780.JPG

After that I dialed in the bias pots without a hassle to 50 mV and the DC offset to 0 mV.

Re-checked the same values and it was still OK.

So I hooked the B-2 to my C-4 and went for a listen session.

Man, what can I say, Steely Dan in the room :music:

IMG_3781.JPG

Next up: the driver boards and the meter board.
 
An (for me major) update here. I installed the driver boards as-is, wired the RCA's straight to them.

View attachment 889634 View attachment 889635 View attachment 889636 View attachment 889637

After that I triple checked everything and went for the first power-up.

I was a bit nervous obviously.

View attachment 889632

Dialed the bias pots fully CCW, hooked the meter on the +85 rail and fired it up....

Clang!

That was the relay, nice. +85 and -85 were 0,5 V off, adjusted them to +85.

View attachment 889628 View attachment 889629

After that I dialed in the bias pots without a hassle to 50 mV and the DC offset to 0 mV.

Re-checked the same values and it was still OK.

So I hooked the B-2 to my C-4 and went for a listen session.

Man, what can I say, Steely Dan in the room :music:

View attachment 889638

Next up: the driver boards and the meter board.
Great job :bigok:
 
Convinced my girlfriend that I cannot work on other projects in the house until the B-2 is finished :p

Finished the left driver board today and the right board is half way. I do see light at the end of the tunnel.

I replaced most transistors, all film caps were replaced with PP films, varistors were replaced, trimmers were replaced with Bourns single turns and a lot of resistors were replaced with precision (and in some cases even 'military grade') metal film resistors. Afterwards the board has been deep cleaned.

I also replaced J102 with a 1,5K resistor and R101 with a 150K (instead if 350K) resistor as per Belgianbrain's and Oilmaster's instruction to facillitate the direct wired input.

I would not recommend the TO-126 heatsinks I used for TR107 - TR110 & TR121 - TR124. They are a PITA to install and the looks are so-so. But when you do use them, install them before you solder the trannies on the board.

I had to move some components to the back of the board to make room for the heat sinks.

Before (except C114 and C112):

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After

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I hope to finish the remaining stuff this week, and then :music:
 
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You have replaced fuse resistors by resistors ??
Where is the improvement ? And where is safety ? Your VFET are no more protected in case of big short caused by avalanche phenomenon
I have refixed plenty B2 and I will never do that
 
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