Hi Jbert9818,
You know, $300 for the repair was cheap back in the 80's. The shop was probably wondering why you refused the estimate. You really did shoot yourself in the foot with that one.
I owned a service center throughout the 80's and 90's. Every so often we would have cheap estimates refused, and I always wondered why. Some folks just wanted to find out what was wrong so their "friend' could attempt a repair. Those guys would complain long and loud that we didn't give them a detailed parts list and list of what needed done. For $30 (1/2 an hour), we gave them a price and overview of what needed to be done. It could take an hour or so to create some estimates. It's sad to think some people regarded a service shop as a free service.
-Chris
You know, $300 for the repair was cheap back in the 80's. The shop was probably wondering why you refused the estimate. You really did shoot yourself in the foot with that one.
I owned a service center throughout the 80's and 90's. Every so often we would have cheap estimates refused, and I always wondered why. Some folks just wanted to find out what was wrong so their "friend' could attempt a repair. Those guys would complain long and loud that we didn't give them a detailed parts list and list of what needed done. For $30 (1/2 an hour), we gave them a price and overview of what needed to be done. It could take an hour or so to create some estimates. It's sad to think some people regarded a service shop as a free service.
-Chris
The seller wasn't very descriptive in their auction listing which was kind of scary to me. The picture they posted shows them as 2 AK and 2 BM ranks; that says to me they're pulls from 2 different B-1's.
Hopefully jbert is lucky and all 4 of these wonderful K77's are still working properly and if so, using the 2 AK or the 2 BM parts in the same channel should allow proper adjustment assuming that everything else that might be wrong with the amp is fixed first.
Attachments
I will not suggest you to " attempt " a repair if you have never refixed a B1 . It will be too bad to waste these V-FET because you tried to make a repair by yourself .
I will strongly recommend you to give it to someone able to do it
5 B1 refixed these last years and 3 to finish this year
Bascom H. King’s write up on the Yamaha B-1 can be found here https://worldradiohistory.com/Archive-All-Audio/Archive-Audio/70s/Audio-1975-02.pdf
interesting details on the circuitry.
interesting details on the circuitry.
R-K,
Did you bother to look at the dates of these posts? Also, while the article from 1975 is historically interesting, many conclusions have been debunked and we know better today.
Old myths die hard and there are people who hold fast, but they generally have little to no technical training.
-Chris
Did you bother to look at the dates of these posts? Also, while the article from 1975 is historically interesting, many conclusions have been debunked and we know better today.
Old myths die hard and there are people who hold fast, but they generally have little to no technical training.
-Chris
Chris, no, I did not really check the dates. We should maybe remove my post (?).
I was mostly interested in the article for the sake of the circuit description of the B-1, which part to me seem right. But of course, these were the first and last of its breed, and better amplifiers are brought to the market since 1975 or so.
I was mostly interested in the article for the sake of the circuit description of the B-1, which part to me seem right. But of course, these were the first and last of its breed, and better amplifiers are brought to the market since 1975 or so.
No, you're fine. The article is of historical interest of course.
Yes, we certainly have come a long way with circuitry and understanding of what makes a difference in sound quality since then. This also illustrates the issues with using very odd, non-standard parts in a design. That amp was an orphan as soon as it was designed simply because the output devices were not adopted by industry and destined to die off quickly.
I was authorized warranty for Yamaha and saw more than a couple of these. Counterpoint suffered the same issues, but those mosfets look like common types (they are not!), and the circuit required very, very close matching.
-Chris
Yes, we certainly have come a long way with circuitry and understanding of what makes a difference in sound quality since then. This also illustrates the issues with using very odd, non-standard parts in a design. That amp was an orphan as soon as it was designed simply because the output devices were not adopted by industry and destined to die off quickly.
I was authorized warranty for Yamaha and saw more than a couple of these. Counterpoint suffered the same issues, but those mosfets look like common types (they are not!), and the circuit required very, very close matching.
-Chris
Of course VFETs was more complicated to use (to bias) than the (Hitachi) MOSFETs that arrived a little later, and so the VFETs went away. Seems many early MOSFETs are also gone, but at least it is a possibility to find something to replace the devices, maybe not good enough and so on. But at last possible to make the amplifier play again. Not so with the B-1. Nevertheless I obtained some some Tokin SITs (VFETs) and was trying to read me up on those. (I could of course just copy Nelson Pass’ designs of course.)
RK
RK
I don't see the point. My entire existence has been all about making things work again, but I've been trained to make certain that you only do that if the device will be reliable and work properly.
It's always sad to condemn a piece of equipment. Often you can, through extraordinary procedures, resurrect some things. But there are times when it is really just better to let the patient die. If the amp will no longer be a B-1, what is the point? Same if it will never be reliable, what's the point? There are times when performance can be greatly improved and reliability enhanced (a lot!), and as long as you retain the same sonic character I believe you should do that. For this reason alone I redesigned the Counterpoint preamps and SA-100/220 family of power amps. (I was authorized warranty for them). But there is very little point in improving an NAD or Naim Nait for example.
In this case, while the Yamaha B-1 was an interesting amplifier at the time, because you can't get closely matched output devices there really aren't any options for properly repairing them. They become a static display at that point, or donor for cosmetic parts to restore a working one.
It's always sad to condemn a piece of equipment. Often you can, through extraordinary procedures, resurrect some things. But there are times when it is really just better to let the patient die. If the amp will no longer be a B-1, what is the point? Same if it will never be reliable, what's the point? There are times when performance can be greatly improved and reliability enhanced (a lot!), and as long as you retain the same sonic character I believe you should do that. For this reason alone I redesigned the Counterpoint preamps and SA-100/220 family of power amps. (I was authorized warranty for them). But there is very little point in improving an NAD or Naim Nait for example.
In this case, while the Yamaha B-1 was an interesting amplifier at the time, because you can't get closely matched output devices there really aren't any options for properly repairing them. They become a static display at that point, or donor for cosmetic parts to restore a working one.