Yamaha B-1 Quickie

[rottalpha]

oh, wait, here is the pile of nasties:

 

[Bert 1100]

Now that was fast ! But top-notch quality nonetheless !
Thanks for all the pictures, very inspiring. It's so good to work on amps that have plug-in boards !

 

[Oilmaster]

And then comes the moment that you have to flip the switch to ON....

 

[Mr. Yamaha]

A quickie indeed!

 

[rottalpha]

And then comes the moment that you have to flip the switch to ON....

Yes, but not before saying a prayer or two. I am mentally preparing for that.

 

[rottalpha]

Now that was fast ! But top-notch quality nonetheless !
Thanks for all the pictures, very inspiring. It's so good to work on amps that have plug-in boards !

well, is as good as its gonna get given the time I have

 

[Bert 1100]

And then comes the moment that you have to flip the switch to ON....

It's always a special moment, followed by good feelings or...not so good...

 

[slimecity]

Wow - theres a lot going on in a very small space inside that amp.

The pullout boards and layout on those boards remind me a lot of Accuphase.

Looks amazing

 

[Mark B]

 

[amr2]

wow, awesome job.

 

[Oilmaster]

It's always a special moment, followed by good feelings or...not so good...

Yeah, isn't that a special moment where everything you did for months might be destroyed within a second.....
Sorry Pete, not trying to stress you

 

[rottalpha]

oh no pressure here, no worries ...

 

[amr2]

pressure pressure pressure

 

[Vint Age]

within a second.....

LOL ...does it take that long?

 

[Oilmaster]

LOL ...does it take that long?

The failure itself not; your brains realising that it happened does

 

[rottalpha]

LOL ...does it take that long?

aaaaa, Yes, between all the Honey-Do's and the million kids here at the house, I found some time this morning...but it looks like I hit a roadblock


and, they are already calling me upstairs and I do not have time to see what heck I missed

 

[rottalpha]

The failure itself not; your brains realising that it happened does

what brains? I have one neuron left and that is on its last leg

 

[clinic-audio]

aaaaa, Yes, between all the Honey-Do's and the million kids here at the house, I found some time this morning...but it looks like I hit a roadblock

installed the PSU/protection boards 1 and 2, adjusted voltages to spec. Actual adjusted voltages: 12V, -25, +25, -200v and -39.8V
installed the 3rd board and tested for 0V between e and a4(step 1-3-2 and 1-3-3)
here I have:
0v on the R+;
20mv on the L+
1mv on the R-
1mv on the L-

it should be 0V on the dot, right?

shorting the a2-b2 on the minus side does not turn the switch on the +B or the -B (steps 1-3-4; 1-3-5)

qq for the group: can anyone verify that both steps 1-3-4; 1-3-5, shorting the a2-b2 needs to happen on the minus side only?

thanks

they are already calling me upstairs and I do not have time to see what heck I missed

B1 service manual is full of error and adjustments procedure is wrong

 

[rottalpha]

B1 service manual is full of error and adjustments procedure is wrong

I have to admit that the manual diagram with the v-fet connectors pinout is lacking...to say the list.

 

[rottalpha]

OK, so I see that Yamaha tried their best to make the manual idiot proof but did not intend on making it lazy proof.
All it took was a quiet moment and a bit of time to look on the schematic and figured out the errors.

The protection circuit works as expected along with the front panel indicators.