Yamaha B-2 restoration journey

You have replaced fuse resistors by resistors ??
Where is the improvement ? And where is safety ? Your VFET are no more protected in case of big short caused by avalanche phenomenon
I have refixed plenty B2 and I will never do that

Great for you.

:boring:

Fuse resistors were used because they are flame proof, not because of their built in fuse.

Besides that, your 'input' in several threads is getting a bit annoying. Your way is not the ONLY way.
 
Convinced my girlfriend that I cannot work on other projects in the house until the B-2 is finished :p

Finished the left driver board today and the right board is half way. I do see light at the end of the tunnel.

I replaced most transistors, all film caps were replaced with PP films, varistors were replaced, trimmers were replaced with Bourns single turns and a lot of resistors were replaced with precision (and in some cases even 'military grade') metal film resistors. Afterwards the board has been deep cleaned.

I also replaced J102 with a 1,5K resistor and R101 with a 150K (instead if 350K) resistor as per Belgianbrain's and Oilmaster's instruction to facillitate the direct wired input.

I would not recommend the TO-126 heatsinks I used for TR107 - TR110 & TR121 - TR124. They are a PITA to install and the looks are so-so. But when you do use them, install them before you solder the trannies on the board.

I had to move some components to the back of the board to make room for the heat sinks.

Before (except C114 and C112):

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After

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I hope to finish the remaining stuff this week, and then :music:
Really nice job as always.:thumbsup:
I choose to keep the micron resistors on mine. Unlike the regular carbon fusible resistors in the Sonys, these are not known to be trouble makers and are definitely flame proof.
New resistors are also nice.
 
Great job! What have you used to clean the bottom of the PCB?

First I clean old and new flux with flux cleaner and a toothbrush. Then I soak it with dishes cleaner (Dutch brand Dreft) and another toothbrush (no water!). Then I soak off the board with excessive amounts of luke warm water and a soft brush to be sure every part of Dreft is gone. And finally I put the board in the oven at 55 degrees Celcius for 50 minutes. After that I wait at least 2 days to mount the board.

I know it sounds scary and all with the water and the oven, but it works great :D

Really nice job as always.:thumbsup:
I choose to keep the micron resistors on mine. Unlike the regular carbon fusible resistors in the Sonys, these are not known to be trouble makers and are definitely flame proof.
New resistors are also nice.

I found quite a few which were off spec ;)
 
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First I clean old and new flux with flux cleaner and a toothbrush. Then I soak it with dishes cleaner (Dutch brand Dreft) and another toothbrush (no water!). Then I soak off the board with excessive amounts of luke warm water and a soft brush to be sure every part of Dreft is gone. And finally I put the board in the oven at 55 degrees Celcius for 50 minutes. After that I wait at least 2 days to mount the board.

I know it sounds scary and all with the water and the oven, but it works great :D



I found quite a few which were off spec ;)

Well it makes the boards look BRAND NEW! Very nice. And there is no danger to the components in the board? I guess because you dry it off?

What about a final rinse with alcohol? Would that speed up the drying process or would you wait the two days anyway? I have saved a few iPhones (ok...two) that had gotten wet by soaking them in Denatured Alcohol for a few hours then letting them dry out for a few days. So I'm pretty sure it doesn't damage electronics.
 
Well it makes the boards look BRAND NEW! Very nice. And there is no danger to the components in the board? I guess because you dry it off?

What about a final rinse with alcohol? Would that speed up the drying process or would you wait the two days anyway? I have saved a few iPhones (ok...two) that had gotten wet by soaking them in Denatured Alcohol for a few hours then letting them dry out for a few days. So I'm pretty sure it doesn't damage electronics.

I think all moist will vaporize in the oven, but I wait 2 days to be absolute sure there is no moist left. But when it comes out the oven, it looks completely dry.

I have no experience with alcohol, except drinking it :beerchug:

You do need to be careful with the flux cleaner on the top side of the board, because it can vanish prints from cap sleeves. I do it very carefully with a small brush in order to not touch the components, only the board surface.

The 'Dreft step' I do immediately after that.
 
This project is in high-speed mode. I'm working every evening after work from 06:00 till 11:00 on it :rockon:

Finished the right driver board yesterday. I'm glad there's 'only' two driver boards.

Same ingredients as the left driver board and I tried make the two boards look a like as much as possible.

I also triple checked everything, pin-outs, PNP / NPN, values old / values new, etc.

Started yesterday with the meter board and the lamp board and hope to finish that tonight.

Before:

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After:

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Yesterday evening I finished the meter board. The least attractive board to work on. Lots and lots of solder pads next to each other.

All electrolytics were replaced with Nichicon PW's and all ten 2SC458 transistors were replaced with KSC1845FTA's. Also one varistor was replaced with two 1N4148's in series.

All other solder connections were redone and most other components were refitted to make the board look more tidy.

Afterwards a cleaning session together with the two connection boards and the lamp board. There’s one smudge left on the lamp board, but it won’t go off with flux cleaner, so I’m not sure what it is.

Also struggling a bit with the LED conversion. The lamps are connected in parallel on the board, so fitting 1 resistor in the 12+ wire can cause problems (1 LED forwarding more current then the others à differences in brightness between the LEDs). If all lamps had a jumper, I could replace the jumpers with resistors, but the lamp on the right doesn’t have a jumper :rolleyes:

So I have to think of something else which does not involve altering the board in any way. It should be 100% reversible.

Forgot to take an after picture of the solder side of the board, will do that tonight.

Before:

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After:

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Also struggling a bit with the LED conversion. The lamps are connected in parallel on the board, so fitting 1 resistor in the 12+ wire can cause problems (1 LED forwarding more current then the others à differences in brightness between the LEDs). If all lamps had a jumper, I could replace the jumpers with resistors, but the lamp on the right doesn’t have a jumper :rolleyes:

So I have to think of something else which does not involve altering the board in any way. It should be 100% reversible.

First off, as always an outstanding job!

I think the board has a 12V power source, correct? How about trying 12V LEDs? These are standard LEDs with the pull up resistor built in. The ones in the link are cool white, but you could adjust with a dye or marker if you want soft white instead. They are also available in other colors and sizes T1 and T1 3/4 (3mm and 5mm)..

http://www.mouser.com/Optoelectroni...LEDs-Through-Hole/_/N-ec21l?P=1yox9d6Z1z0ysw2

EDIT: If you stick with incandescent bulbs these will work using the original holders: http://www.mouser.com/ProductDetail/JKL-Components/7219/?qs=sGAEpiMZZMucm/%2bFOY0TQtr/chrLORC03%2bO1Q9USLQs=

Also @Vint Age had this to say here:
"I wouldn't use regular LEDs because they'll have bright spots. I used 360° diffused LEDs from Superbrightleds* in mine. The whites have the highest brightness. The blues have an almost black light look/effect that I really like and the yellows look the most like the original incandescents but are a little more subdued. I also have one with red ones that I think look real nice.

It's a pretty easy mod to do. I installed them in the same Stanley holders that the bulbs were in and I added a single resistor of suitable value in series with the 12V lamp line to the board. You have to pay attention to the polarity and make sure you install them all in the same way. If you don't like it, it's pretty easy to revert back to the bulbs."
*https://www.superbrightleds.com/cat/through-hole/filter/Viewing_Angle*ranged,121,39,360:
 
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Yesterday was a great day. I needed the B-2 to be ready, so I took a half day off and spent all my time till 10:00 PM on it. It was a stressful day :idea:

The situation yesterday:

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At first, I needed to come up with a solution for the LED's. Four in parallel with one resistor can cause problems. So what I did, was pretty simple, I replaced all jumpers with resistors and for the last LED (on the right) I removed the pin which makes connection to the minus trace and soldered a small wire on the minus leg of the LED inside the original rubber lamp holder. Afterwards I connected a resistor on it and soldered it on the minus trace of lamp number 3. In that way all LED's have their own resistor and the board was kept original.

I used 820 Ohm resistors to get 12 mA on the LED's and I used 140 degree radial beam warm white ones.

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Then the speaker switches, they needed to be cleaned and conserved. They had to be desoldered from the board in order to do it.

I was pretty shocked by how clean they already were :eek: Just some mild oxidation.

Internal parts were deoxidized and faderlubed, the mechanical parts were lubed. The board was cleaned afterwards.

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Forgot to take after pictures.

Then I replaced the orange +85 and the -85 green power supply wires between the power board and the driver boards. The old ones were pretty brittle and have broken off a few times during the process. I used some nice silver plated wires in original color, but with larger diameter. I also changed the E wires between driver boards to power board with black ones to suit the internal design.

Then it was time to reinstall all boards.

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Then it was time for first start-up. Exciting!

Bias pots closed, meter hooked on +85. Power on, CLANG! Nice.

+85 and -85 were still spot on.

Then bias and dc balance. I'm not very happy about the Bourns single turns. Very hard to adjust bias at a round number. Took me half an hour to get them both at 60 mV. But it remains stable. Dc offset is around 1 mV.

Not too happy about the LED color, they are too yellow. Maybe I need to change them.

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Some listening tests, sounds great! :music:

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Then time to assemble!

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What can I say, I'm really happy with the end result and the B-2 sounds amazing :music:

I also like to take this opportunity to in special thank @Oilmaster and to give him nearly all credits for this rebuild. I wouldn't come this far without him. He sourced most parts, pointed me to the right parts, matched transistors, sent me resistors with pre-bent legs, sold me parts from his parts stash and guided me through the whole process. I have learned A LOT! Actually I was some kind of contractor who just put the parts together :biggrin:

I also like to thank all other members for their input, tips and tricks :bigok:

And also the Chinese for building cheap, but very reliable solder stations, desolder stations and component testers :p
 
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