@Vint Age I guess Pete can tolerate at least some risk. I guess since its only two sets of B-2 V-fets at risk its ok
Athanasios
Yamaha B2 - the "why" and the "how" of a comprehensive rebuild
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@Vint Age I guess Pete can tolerate at least some risk. I guess since its only two sets of B-2 V-fets at risk its ok
Athanasios
Agreedy ... I mean agreed.@Vint Age I guess Pete can tolerate at least some risk. I guess since its only two sets of B-2 V-fets at risk its ok
If he's like me he has a few spares for just in cases.
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Exactly what I said back in the day in 1978 when I first got to listen to it as a young Yamaha and others warranty tech; oh how I wished I could have brought one of those beauties home with me back then.
Understood and appreciated!
To my thinking a messy bench is a happy bench and if you tidy up too much you'll never be able to find anything.
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To my thinking a messy bench is a happy bench and if you tidy up too much you'll never be able to find anything.
Exactly!!! Every time I add storage or more shelving etc to "clean" up my work area I can never find where I put half the stuff I organized!!
nakmandan
Vintage Nak enthusiast
To be a fair and honest assessment of an "as is" amp, I think all switches and pots would have to be cleaned, relay contacts cleaned (as long as not burned) and offset, voltage and bias should be set to spec. Basically, a factory adjusted amp working as designed, with all original components (or at least what it came in with) and no modifications. Trouble is, just to get an amp to that point can be a lot of work and you'd end up doing some of the work twice. I doubt too many amps would come in for service ready to go under test and as already said, pushing an "as is" amp to its limits for testing could be dangerous for the amp. Most would probably fail miserably in "as is" condition.
When I take cassette decks in for service, I do evaluate them before anything is done other than cleaning and demagnetizing the tape path. But a lot of decks are brought in non-functional so it's not always possible. Once in a while the whole transport needs to be overhauled just to be able to test the heads. Sucks when you do all that work only to find out the head is worn, as it is not always visible to the naked eye and have to have frequency response tapes run over them to determine their status.
When I take cassette decks in for service, I do evaluate them before anything is done other than cleaning and demagnetizing the tape path. But a lot of decks are brought in non-functional so it's not always possible. Once in a while the whole transport needs to be overhauled just to be able to test the heads. Sucks when you do all that work only to find out the head is worn, as it is not always visible to the naked eye and have to have frequency response tapes run over them to determine their status.
Not "as-is" but "as it was new" about 45 years ago. And yes, it is a lot of effort to get it to this condition and not sustainable or repeatable, so that's why we need new parts and some mods.
Thake a look at this new clip and let me know your feedback.
Keep in mind that this is not a scientific test, but directionally should provide a sense of the original unit performance,(or very close to as it was new), vs one that was fully restored as I share in the prior video.
@Vint Age I guess Pete can tolerate at least some risk. I guess since its only two sets of B-2 V-fets at risk its ok
Agreedy ... I mean agreed.
take a look and let me know your thoughts:
WOW , now that is impressive Pete!!
Great explanation and description of what you were trying to accomplish and measure.
I wish I could have hear these back then when my ears were better than they are now .
PS: is that new switch board one of mine in the back ground ? lol
Athanasios
Great explanation and description of what you were trying to accomplish and measure.
I wish I could have hear these back then when my ears were better than they are now .
PS: is that new switch board one of mine in the back ground ?
lolAthanasios
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Yours isn’t far away from that bench.WOW , now that is impressive Pete!!
Great explanation and description of what you were trying to accomplish and measure.
I wish I could have hear these back then when my ears were better than they are now .
PS: is that new switch board one mine in the back ground ?
Athanasios
I am glad the video made sense.
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thank you Dan
there's a "sister" video with the "revitalized" version.
Thanks for that awesome comparison videos! Wish I had an analyzer like that on my bench. Before I retired the company I work for had 2 Audio Precision Analyzers for factory testing in both the analog and digital domain. I wanted to bring my B-2 in for similar testing to yours but the test manager was too paranoid due to their cost so it never happened.
Besides the difference in distortions, which to me is essentially none existent, I also noticed that there's a slight difference in the harmonics amplitude between the 2.
My first thought is that by using the analyzer to do a slight bias tweak on the mule B-2, it might bring it a tad closer to the other one ...
Please feel free to prove me wrong.
Pete has inspired me to up my game with my rebuilt B2s.
I look forward to restoring the function on these units that has been disabled.
I ordered two full sets of everything he's offering and the fun begins. I may even put my third parts unit back into service, since it's not missing much in the way of parts.
I'll share a few pictures when things get completed, but it'll be awhile...
I look forward to restoring the function on these units that has been disabled.
I ordered two full sets of everything he's offering and the fun begins. I may even put my third parts unit back into service, since it's not missing much in the way of parts.
I'll share a few pictures when things get completed, but it'll be awhile...
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Yes, that is one of the best uses of this analyzer and I leverage it all the time. Sometimes there are small difference between the two channels of the same amp that can be addressed this way.
In this case they were both set at about 40mv for this exercise purpose.
In this case they were both set at about 40mv for this exercise purpose.
Side note: can you say B-1 bias balance
Understood and appreciated!
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Believe me, that's a whole other thread.Umm..... Ok what do I need to know once I begin work on my B1 ?
Believe me, that's a whole other thread.
Yep, I know, been reading the B-1 SM.
I'll post on it in my B-1 thread once I cross that bridge.
Athanasios