Sansui B-2301L / Sansui C-2301 restoration

[Bumpalump]

Hello, in this topic i will show you process of the restoration those separates, one of the best from past years, direct competition for the top of the line Technics, Sony, Accuphase

We will start from power amplifier

Some photo from the bottom

1st I removed right power amp module, its really huge, also i like the connections design, everything can be easily disconnected

Premium U-Con by-pass capacitors

Really huge and solid emmiter resistors

Will be lots of desoldering and soldering

 

[Hyperion]

This is going to be a reminder for me of when I tackled a B2301L & C-2301

 

[Bumpalump]

One module unscrewed

Capacitors removed

Lots of glue here

Its a long way to remove glue from epoxy boards

Capacitors measurments 470uF 63V



They are fine

Another capacitors measurments 470uF 50V


They are all fine, so will be installed again

New thermal grease, resoldering, and one board is ready
Some parts required cleaning

Second board had more glue

 

[Bumpalump]

Power supply check

Both channels ready, assembled and its alive

 

[Harolda]

Power supply check
View attachment 2820789
Both channels ready, assembled and its alive
View attachment 2820790

View attachment 2820791

I like that your rebuild, the build quality of that amp and that Enigma Album

 

[DB-7]

If you feel this post doesnt belong, you can get the mods to delete it.
Just a few curious questions.
Were there issues/problems with these units or are they being done just for refresh/preventative maintainance?
Are they JDM or international voltage? I see Lots of Japan only versions out there lately, not many of the other. There is a JDM set forsale here locally. (Ontario, Canada) the guy wants a crazy amount of $$$ for them.
Love your work and postings.

 

[JSMATT]

Bumpalump:

Thanks for sharing.

The 2301L I rec'd suffered from very, very poor packing and due to the weight of the transformer and the rough handling, it required a complete redo of the framing that holds all the fiddly bits together (That has been done, but requires a final coat of paint.). I do not see any signs of that on this 2301L which is great.

I took the approach of Hyperion for the 2301L he worked and replaced all the electrolytics on the boards. And, when the old ones were measured, they all were in spec.

That is my experience overall in the limited work I have done on the 80s Sansui pieces I have - the electrolytic capacitors all measured fine, but I replaced them anyway. I believe the common wisdom of people with way, way more experience than I is that the electrolytics are part of a multi-decade Preventive Maintenance effort and that works for me.

I would be very interested to see what the distortion measurements are for this beast. Is that something you anticipate doing?

 

[Bumpalump]

@DB-7
Main problem is the scratchy controls, rest is just preventative maintenance (glue, measuring capacitors, resoldering)

@JSMATT

In low/mid grade eqippment i usually change the capacitors, in top of the line i preffer to stay with originals, i can make measurments since my analyzer allow to make measurments with floating ground

 

[Bumpalump]

Time for controls cleaning

Before

After

A lot of Riken premium resistors here

Flat amp board

Glue removed, capacitors measured

Power amp offset before adjustment

Flat amp + power amp before adjustment

Flat amp + power amp after adjustment

Lamp replacing

 

[Bumpalump]

Lets start with preamplifier

I allways like to read those descriptions



Top view

Undercover

Line amplifier removed

Board removed

Most time consuming, glue removing

Capacitors were really bad, not surprised, much heat in this enclosure, some of them already replaced, together with new relay

After few hours its ready

 

[Bumpalump]

Now, the phono stage

Capacitors near dead

Glue removed, some parts required replacing like zener diode and one 82nF capacitor

Board completed

Now, adjustments of the one side



Parts replaced from both phono boards

Second line amplifier board during repair



All the parst replaced from both line amplifier boards

 

[bolero]

Woah, those electrolytics seem huge, for the phono preamp? Does it run at really high voltage? Maybe it's just a camera lense effect...

Anyway, nice work!

Another newbie Q: don't phono preamps usually have a few more poly caps in them? I think I only see 1 poly cap in there?

 

[GrisPato]

Woah, those electrolytics seem huge, for the phono preamp? Does it run at really high voltage? Maybe it's just a camera lense effect...

Anyway, nice work!

Another newbie Q: don't phono preamps usually have a few more poly caps in them? I think I only see 1 poly cap in there?

This amplifier is a little different then what you (we) are used to. The big cap (C-22) that you see in the picture with 82000 on it is a polystyrene cap from 82000 pF. The capacitors you see with nice belly and the transparent top are also polystyrene. This was filled with the latest and best components available at that time, X-balanced ( alpha) circuit topology in the phono and control amp stages!

 

[bolero]

Lol, it figures!

Thanks!

 

[JSMATT]

A lot of time and TLC to get the tons of glue off of that board ("Second line amplifier board during repair"). Looks like al the legs you lifted were not adversely affected by the glue tho.

Am curious as to why you disassembled the rotary db switches on the back of the power amp. Did you have poor readings or 'simply' take advantage of the state of disassembly to clean them?

 

[Hyperion]

That picture! - that's exactly what I had to do when I did one of these. It was simply not possible to make a proper job of cleaning the glue off without lifting those components. The glue had touched the leads of so many, in most cases not doing them too much harm. Cleaning the glue off is so very important, drastic measures are often needed.

Great picture.

 

[Bumpalump]

A lot of time and TLC to get the tons of glue off of that board ("Second line amplifier board during repair"). Looks like al the legs you lifted were not adversely affected by the glue tho.

Am curious as to why you disassembled the rotary db switches on the back of the power amp. Did you have poor readings or 'simply' take advantage of the state of disassembly to clean them?

I lifted legs to not expose them with so much heat during glue removing

Switches were screatchy, but anyway, i allways disassembly every controls and clean them

 

[Bumpalump]

2nd day of the work

Time for power supply

Another glue victim

I tried to repair



Success

Rest of my work, glue removing, capacitors replacing and soldering



Parts replaced from both power supply boards

 

[Bumpalump]

Protector board rework

Lamp replacing

Controls accesing

Cleaning

Soldering rivets

 

[GrisPato]

I tried to repair

Great work on this one. Never seen someone repair this.
Really nice to see you making this efforts to keep the original high quality components in but not hesitate to change out a component when it is needed!
dobrze zrobiony