BA-3000 Restoration underway

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Hello All

I'm starting a new but familiar thread here. I've got the 100v AC mains question out of the way and I have fixed the left channel popping/static issue. the problem was in the buffer section on the filter board. I reworked that entire board then I ran the amp for several hours on Saturday and Sunday. All was well except for some flutter in the right channel meter. Now that I know I have a clean sounding amp to start with, I've pulled the two driver boards and PS board. I'm in the process of reworking the PS board now and I'm hoping to get the driver boards done this week end.

Jim H.
 
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Update

I'm in Deep.

After reworking the PS & Driver Boards then testing the amp to see if I had corrected the static/popping in the left channel. I started in on the next step of the restoration.

The boards for the output transistors don't have feed through's or via's. The boards use pin sockets for the output transistors as well. So there was no need for me to pull the blocks apart. I removed each transistor, cleaned up the pins and removed the old thermal compound then applied new. I have the new 2200uf caps installed. I'll be going over the circuit protection board next.

I have to say, all the caps that I pulled so far tested at greater capacitance then the new ones I put back in. Is there really any sense to a full re-cap. I'm starting to wonder.

Jim H.
 

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The greater cap value is a sign of age.... for the SMALL amount of cheese to replace AND your in this deep PLUS you don't want to be luggin this in & out of the cabinet, rack, closet in a year... it's CHEAP INSURANCE ( along with fuse resistors )
 
Thanks...
I didn't know the value would increase over time.
I did overlook doing the small signal transistor tucked inside. I believe that handles the bias current correct?

Jim H.
 
Acid Test

Here's the latest on the BA-3000 restoration...

To keep it short. I've gone over all the boards, replaced every electrolytic cap, matched differential pairs, replaced all trimmers and re-flowed most all solder joints. Did a test last weekend using a secondary system. I adjusted the Bias and DC offset to spec. All went well. I was very pleased at how nice the amp sounded. I wanted to add balanced inputs the rear of the amp since I'm currently using balanced interconnects with the amp that the Sansui is going to sub for from time to time. I wanted to convert the balanced inputs to unbalanced/SE actively. To do that I purchased a bare bones converter that utilizes A single BB OPA2134PA Op amp. I replaced the BB OP amp with a Burson discreet dual Op amp for better... well we all know...

Any way with some hesitation and doubt on how things were actually going to shake out. I brought the Sansui up to my main system for the "acid test" I pulled out the tube amp and carefully connected every thing up including the balanced to SE converter. Fired it up, at first the amp wouldn't come out of protection with the inputs from my pre-amp hooked up. Not sure why... After some trials and tweaking I got it working. And from there things just got better.

The Sansui is quiet. No hum, no hiss no noise and sound wise... it gives my tube amp a run for it's money for sure. I cant be more pleased so far on the progress I made on this restoration. When I brought this amp home a little over a month ago, it had serious static/popping in the left channel. The main heat sinks got quite warm in a short period of time and the amp sounded just horrible. So THANKS to All who answered my questions I had in order to get this amp to where it is now. This truly is a labor of love for me.

Quite a bit of work to do yet though. I need to mount and tie in the balanced converter somewhere inside the yet amp yet and mount the XLR jacks along with switches to select from Balanced to Un-balanced inputs on the rear panel. Plus I want to eliminate some trimmers on the converter with fixed resistors. And for the final touch, re-do the lighting on those cool old school VU meters. I'm toying with surface mount LED's. I'd like to get the color to match the TU-9900 I have, although at some point in the future I see myself going over the tuner as well and I know I'll be putting in LEDs there too.

Jim H.
 

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I haven't posted for a while.

So here's the latest news on the restoration of my BA 3000. I've been running the Sansui for a few months now. I'm very happy with how it turned out. The sound is detailed and spacious. The amp looks fantastic, and it's so nice to have it all back together 100% complete. I pulled it out of the stereo cabinet today to get a few photographs of it. If you guys are interested I'll post more pictures including ones on the mods I performed. As I was warned, the mods I wanted to do were no easy feat. Feast your eyes on this puppy.

Fisheye.jpg

BA 3000.jpg
 
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More pictures would be appreciated by all, the ones posted already have made me hungry for more, please do include those of the modifications you have performed.
 
Thanks to all for your words of encouragement

A lot to cover here so let's see how it goes. I really wanted to add balanced inputs to this amp. For reasons known to me and mentioned in another thread this was a must. I had the holes for the balanced jacks machined in the rear panel. Drilling a hole that large in the sheet metal would have ripped it up and made a mess. The machinist who did the work is good, he did a fantastic job and didn't put any marks on the real panel either. I was really sweating that out. The mode selector switch was re-tasked. It now selects between either the RCA or balanced input jacks.
Selector Sw..jpg
The RCA inputs follow the original circuit path through the volume pots, filter board, driver boards and so on. The Balanced inputs bypass the pots and filter board. They feed directly into an "active" balanced to unbalanced converter. After some experimentation I chose to go with a converter from Elliot Sound Products (ESP) He sells a bare circuit board and you populate it with the components of your choice. It's designed to use two op-amps. I chose to go with two "Dual Discrete" op-amps from Burson Audio. They plug right into 8 pin sockets just like a regular op-amp.
Balance to SE Board.jpg Balance to SE Board 2.jpg
To feed the op-amps with voltage, I tried tapping into two different supply rails in the Sansui to get the plus/minus voltage they needed, and ran into weird operational problems of the Sansui amp it's self. I wound up having to install an Accopian encapsulated +/-15vdc supply.
15v Supply.jpg
The problems didn't stop there though. The Burson op-amps are specd. to handle up to 18 +/-vdc. When I ran them at 15 +/-vdc a couple of transistors on the boards ran very hot to the touch. Somewhere around 160 degrees F. And that was while the front of the amp was still wide open. I didn't like that so much, so I put a positive and negative 12v regulator on the output of the Accopian supply. That dropped the temps of the hot transistors dramatically. I feel much better about that now. From the balanced to unbalanced converter the signal goes directly to the input of the driver boards. So the amp is running wide open when the balanced inputs are being used. I imagine it would not be a good idea to throw the mode switch while the amp is operating. That pretty much covers the mods done for the balanced inputs. It took quite a bit of effort and time to iron out all the "how to's", "what if's" and "wtf's". Of course space was tight on just about every aspect of that whole ordeal too.
Supply&Balance.jpg

More to follow.
Jim H.
 
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Next Up...

I needed to upgrade the speaker terminals. The original terminals wouldn't accommodate the terminations on the speaker cables I'm using. Nothing major but still easier said than done. Fortunately I was able to remove the old binding post's and install new post's in the original plastic blocks. And I didn't screw anything up in the process. Naturally I replaced the caps and resistors on the so-called Zobel filter network also.
Speaker Terminals.jpg

Here's a picture of the rear of the amp.

BA 3000 Rear.jpg

Is that sweet... or what...
 
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The Last Mod, LED lighting for the meters.

Thanks for the comments on the above. For the meter lighting, I started off by making simple metal holders out of thin brass sheet stock, similar to what the original bulb holders are like. I took some 3/8 inch thick clear acrylic and cut it by 1/2 inch wide. The acrylic runs the width of the brass holders I made. I first experimented with 8mm LED's by drilling holes into the acrylic and pressing the LED's in. They worked OK but were a little bulky and the lighting wasn't completely even. So I went with surface mount LED's. I had experience in working with them before. Very simple to do once I figured out which type of LED to go with. I wound up going with a warm white (3000K) 6SMD. They are square and have nine emitters on one chip. I used adhesive backed copper foil tape about 1/8 inch wide as conductors for the LED's and ran two strips of it the length of the acrylic. Then it was just a matter of soldering the LED chips to the copper foil tape.I Drilled two holes through the acrylic to run the wires from the back side of the acrylic to the front where the copper is. I put a bridge rectifier and filter cap on the 5.7vac. feed that ran the original bulbs. I put two 3 watt resistors in parallel to drop the voltage to the right level. At the moment I cant remember the value of the resistors, they are fairly low, just a few ohms. I made colored filters out of .010 inch thick Lexan plastic. Tamiya makes a translucent model paint in various colors. Their blue color is sort of a bluish green and with the warm white LED's I feel the end result of the dolor is what I was shooting for. It's an enamel based paint and thins easily with alcohol. Very easy paint to work with but I did have a hard time laying the paint on both filters evenly.

In the photo below you can see the rectifier and filter cap laying on top of the Accopian power supply. Eventually I put a piece of Velcro on the cap and the panel just behind it to secure it in place. Just above is one of the LED assembly's. In the picture it's laying upside down and facing toward the back. If you look hard enough you can see through the back of the acrylic to the front where the copper strips are and the white evenly spaced squares are the LED's there are nine per meter.

LED&Bridge.jpg


This photo shows the LED holders in place. I apologies for not getting better photographs.

LED's in place.jpg

I know a lot of Sansui owners would like to convert their amps lighting to LED's. If you have the time to play around, I think this is the way to go. The end result is the meters light up even, fairly bright and it's the best I've come up with so far.
 
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A few More Photos

BA 3000 & Power 2.jpg

BA 3000 Side.jpg

BA 3000 Front.jpg

I feel fortunate to have come across such a clean representation of this amp. To me, condition means a lot. I take pride in the Hi Fi equipment that I own and this piece fits right in. This interest in Sansui all started about two years ago when I was looking for a decent tuner and brought home a mint TU 9900. It didn't take me long after that to realize how nice this Sansui gear is.

Jim H.





 
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That meter illumination looks really nice - you did a lot of work there and it has paid off in spades. :thumbsup:
 
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