Yes, the out-house shaped LGs need to be replaced.2SC458 affected type and should be replaced is 2SC458LG , this package :
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all the other don't need to be replaced , TO92 package :
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If your protection relays are still the originals, replacing them adds another plus to the sound quality.What other elements would recommend updating?
Thanks!If your protection relays are still the originals, replacing them adds another plus to the sound quality.
All the B2 I have refixed were with original 2SA810 and 2SC1452 . They still work today as all my B2 .
This is a good advise
The 2 most significant sonic changes I've made to my own B-2 was to replace those relays with new ones and bypass the front panel switches.
Hi MiamiBoy,I have completely refurbished two B2's and spent a lot of time consolidating notes from many threads on this subject. I compiled an Excel sheet of very component I replaced, the new part# and their location in the amp. Will also share some key pictures if you like. Some I already posted in previous threads.
If you are interested, PM me your email and I will send you some items that you may find helpful.
I don't know your history or how familiar you are with amp work but please familiarize your self with the many warnings in other posts on how to protect the VFETs and discharge the caps before doing any work.
Small update here. I replaced the single turns with 500 mW multi turns and it's MUCH better. Bias spot on at 40 mV and DC offset spot on at 0 mV. Verry happy.
I went from 60 mV bias to 40 mV and it sounds much better. Less boomy, more seperation between instruments. But I still wonder whether imaging can be improved. The M-2 I had spreads the instruments all across the room, but with the B-2 the instruments are very near the speakers.
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I also changed the LED's to amber and made the lamp circuit series instead of parallel. I removed the jumpers / resistors and connected the LED's in series with wires and without mutilating the board. This was possible by removing 3 lamp holder pins and use the holes isolated to put the wires through. I added one multi turn pot to have the ability to change brightness. At day light it looked pretty close to original, but at night it was much too orange.
So, back to the drawing board.
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how long did you search this site? You might not find a full BOM, but most likely more than enough information.can't seem to find much info on parts used to rebuild them
some of us, more than you thinkHow often would most owners of this amp be comparing two sets of speakers anyway?
it does not have to be that wayCompared to how often one channel cuts out because of all the switch contacts?
true, you and "even out" less efficient speakersIf a user wants to A-B two sets of speakers, the volume adjustment for each set of speakers would be welcome, so that they can be compared at as close to the same sonic level as possible
Yes, the original is nothing to write home about.But the reliability of that circuitry, compared to a normal volume control and speaker selection circuit, isn't good.
Excellent Thread Mr. Yamaha. Any chance you could provide a complete BOM for the parts used in your Restoration? I am starting on a B-2 I recently acquired and can't seem to find much info on parts used to rebuild them.
There are enough threads on B-2 rebuilds here for you to find about 95% of the parts information you need. The other 5% you can ask about. However, and this is coming from personal experience, replacing parts in a B-2 is risky business and you better have the discipline to not do anything on a hope and a prayer. There is a method to bringing the B-2 back up to speed, and you need to RTM and read all of the threads here until you are very clear on how to do this. You only have one chance to do it right or you may lose those vfets. Unless you have had a lot of B-2 repair experience, this is not the typical weekend recap project. Expect to spend many hours researching and learning before you even begin.