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Yamaha B-1 Quickie

rottalpha

rottalpha

Yamaholic
Subscriber
Hi Gang, time to start a B-1 thread of my own and stop highjacking other's.

A little while back I purchased a nice looking B-1 with UC-1.
I played it for a bit after I got it and it sounded so so, but nothing to write home about. At low volumes it was definitely lacking the definition I expected. It was also getting extremely hot...way hotter than my BX-1s which I was also running at the time.
Needless to say, It needed TLC, so I packed it up and stored it ....until recently.

Time has come to dust this B-1 off and give it a "Quickie". The goal is to have it singing like a canary by Christmas. I do not intend to do a full rebuild just yet, but I will go a bit beyond to the average recap job.

Besides a lot of dust and a bit of corrosion on the top of one of the driver boards brackets, I do not see anything out of ordinary. The corrosion seems to have originated from a liquid spill at some point in the past. Very minimal damage and non consequential now...
Here are some shots of under the hood:
IMG_20171126_205626182.jpg

Some heat damage to one of the caps in the middle PSU/Protection board
The good news, this thing is cleaning up very nicely. I think I will make a model citizen out of it :D

Here are some of the individual boards:


IMG_20171127_204818972.jpg
IMG_20171130_033001679.jpg
This thing was well roasted. One of the legs was no longer attached OUCH! Lucky Lucky B-1!
This is a bad design. The three fat 2w resistors below are roasting this cap every-time the amp is on. I am moving it to the back side and will stagger those resistors so that the lower ones do not bake the ones towards the top.
Still working on it, but this is kind 'a what I have in mind:
IMG_20171211_140819792.jpg
IMG_20171211_140802171.jpg


Nothing eventful on this board, except dirt and corrosion on the TO220's heatsinks:
IMG_20171128_231526535.jpg
Edit: I should have mentioned that I replaced a hand full of 458s on this board
IMG_20171211_140733064.jpg

IMG_20171128_231515333.jpg
IMG_20171202_141526428.jpg
 
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continued...
IMG_20171128_232431904.jpg IMG_20171211_140752791.jpg
here I committed the ultimate sin by a certain someone's standard in terms of replacement components choice....I promise to repent :p

also...ran out of silver heatsinks so I went to black instead.

IMG_20171211_140336803.jpg IMG_20171211_140406000.jpg

IMG_20171211_140525921.jpg

on the driver boards I will replace all carbon resistors and ALL caps. I found some of the R&Cs way out of spec. I already started the process.Waiting for parts...

Other changes I did so far was to replace all known trouble maker semis such as the 2sc 458s on the PSU boards and the 2sa810s on the driver boards.
 
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Lesson learned here is that if Saint Nick says he won't brig you the goodies you wished for, for Christmas and you want to play Christmas tunes on your B-1, you go get yourself a piece of Garrolite, some screws, a set of caps and you make it your own big cans contraption.
 
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Quite a machine. I have never seen the inside before today. It was great that it was designed as a modular amp. Your choices of changes made a lot of sense and will definitely help with the heat distribution that the original design did not do. The staggered resistors was simple, but will be, no doubt, effective. What a remarkable amp. Nice choices and nice job.
 
KingBubba said:
Quite a machine. I have never seen the inside before today. It was great that it was designed as a modular amp. Your choices of changes made a lot of sense and will definitely help with the heat distribution that the original design did not do. The staggered resistors was simple, but will be, no doubt, effective. What a remarkable amp. Nice choices and nice job.
Click to expand...
Thank you,
yes, quite a machine indeed. Very complex circuitry but great acessibility under the hood, ...from the modular design perspective that is.
Same goes for its matching pre.
 
Bratwurst7s said:
Nice work. And nice heat sinks. Do you have a source and part number to share? :)

Cheers,
James
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yes, they are the B-1 special edition. Part number is #makeyourown.
They come in a large sheet of copper format with sheers and instructions on how to make them so that when mounted on those TO-126 replacements, they do not touch the other components around and the B-1 chassis, like other premade aluminum ones would :)

Here is some of my stash:
IMG_20171209_205836738.jpg
 
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clinic-audio said:
Yes , I did
no problem with them
What are you looking for ?
Click to expand...

Glad to hear that. I already pulled the trigger on some of these Bourns trimmers
this looks like a perfect fit for the bias trimmers in the B-1. Not in stock at any other major retailers
 
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808_state said:
Looking forward to hearing your impressions as you work through it!

A nice B-1/UC-1 popped up on hifido today but of course sold out in a heartbeat...

http://www.hifido.co.jp/KW/G/P/A/E/0-10/S/C17-12931-68874-00/
Click to expand...

Yes, really nice indeed. Super good price considering the condition and that it went through maintenance already.
I do see some rust on the end of those screws tho. This tells me there might be corrosion somewhere else on the chassis of that amp.
You would need to be very cautions when buying from Japan. It is a hit or miss. Looking at the screws is a hint of possible hidden issues.

I purchesd the B-1 (below) not to long ago from Japan and it is in outstanding physical condition. Absolutely no chorosion anywhere and I am almost certain I am the first person to pop the hood since it left the factory:
IMG_20171120_215425186.jpg
 
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808_state said:
Looking forward to hearing your impressions as you work through it!

A nice B-1/UC-1 popped up on hifido today but of course sold out in a heartbeat...

http://www.hifido.co.jp/KW/G/P/A/E/0-10/S/C17-12931-68874-00/
Click to expand...
you should keep an eye out here in the US as well. Sometimes they come up for sale. The one I am doing the "Quickie" on in this thread, I purchased on the auction site close to a couple of years back. It used to be owned by another AKer. That gave me more peace of mind then even buying from Hi-Fi Do :)
 
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