Sansui AU-222 Restoration by Total Novice

[Spider27]

Hello,

 

I saw some posts here that super cool members restore vintage amps and share the process with other members. Every time I saw those posts, I feel urge to go for it myself but always made excuse to postpone another day.

 

During this crazy COVID-19 lock-down period, I stay home most of the time and decide to get vintage Sansui amp to try restoring myself to kill some time and get myself busy.

The one that I got is AU-222 model. I chose this because it is ideal size for my desktop setup and it looks simple enough for a novice like me. 

 

When i turn it on, I hear some crackling noise come and go on right channel and it does not matter which source it is selected so my guess is that there is an issue with right channel output.

And, overall sound is a bit dull and highs are rounded. Not sure if it is Sansui's typical sound or it is because caps are end of their life. 

 

Here is an inside photo. It looks fairly clean and all caps are original Elna light grey colour. I do not see any pregnant caps but I guess that it is better replace all of them.

 

Here are a few questions if I may ask... These questions might be super dumb to ask.. I tried to find myself by browsing web but could not figure out myself. 

 

1. Do I just replace all of Electrolytic Capacitors or need to replace Mylar and Mica Capacitors too?

2. What brand of capacitors are good replacement of original Elna Grey caps? Nichicon is good replacement?

3. The original Caps says 1500uf, 63WV. Does this mean that it has to be 1500uf at 63v or can it be 1500uf 350v?

4. What is the typical issue that cause one channel crackling noise coming and going?

 

Thank you very much in advance and hope everyone stay safe...

 

[tubularbells]

1 hour ago, Spider27 said:

1. Do I just replace all of Electrolytic Capacitors or need to replace Mylar and Mica Capacitors too?

2. What brand of capacitors are good replacement of original Elna Grey caps? Nichicon is good replacement?

3. The original Caps says 1500uf, 63WV. Does this mean that it has to be 1500uf at 63v or can it be 1500uf 350v?

4. What is the typical issue that cause one channel crackling noise coming and going?

 Sounds like a fun project and and it appears you have a good foundation for which to start.

 

As for your Q's

1. Rule of thumb is to replace the electrolytics starting with the largest and working your way down to the smallest (as usually the biggest ones are doing the heavy lifting and tend to age faster) but as there's only approx. 22 caps id personally be inclined to do all of them.

 

2. As for brands any respectable companies like Nichicon, Panasonic etc. will be fine

 

3. There is no issue using caps with a higher working voltage (some may argue ESR isnt as good) but just beware the caps have the same form factor and will fit into the designated position as higher voltage equivalents tend to be bigger.

 

4.  Crackling could be a number of things but most likely a switch, potentiometer or dry cap but could also be a dry solder joint/bad connection.  i'd start with giving all contact a good spray using contact cleaner (working the pot/switch as you do so). I use this for pots & switches. https://www.jaycar.com.au/contact-cleaner-lubricant-spray-can/p/NA1012

 

Also if you dont already own one you'll need a solder pump and/or solder wick to remove the solder from the components but im assuming you would already have this seeing you willing to undertake a project such as this and most importantly be safe! Ive been belted by mains voltage enough times now to know it need to be treated with care and respect so make sure its unplugged whilst doing this.

[Spider27]

Got Contact cleaner from JayCard and cleaned all pots and the right channel crackle remains same. While waiting for caps to arrive, time to check the all of solder joints to make sure if there is any cold solder. 

[Batty]

Great project for a beginer, you'll be an expert in no time. 

[pete_mac]

The crackling sound is likely to be one or more of the small signal transistors - they are probably 2SC871s. BC550s are an appropriate substitute.

 

Regarding the larger capacitors, you can also increase their size. Two are the output capacitors which are in the direct signal path,  and the rest are power supply filter caps. Personally, I wouldn't go higher than 100V for any of these.

 

Let me get back to you with some specifics.

Edited April 2, 2020 by pete_mac

[pete_mac]

Grab the free schematic from hifiengine:

 

https://www.hifiengine.com/manual_library/sansui/au-222.shtml

 

C601/602 - install 1.5uf WIMA MKS2 or Panasonic stacked film capacitors or similar  - you will need narrow lead spacing of 5mm to suit

C609/610 - 10uf WIMA MKS2 if you are keen and can source them, otherwise I'd suggest Nichicon UKL low noise caps  - you will need narrow lead spacing of 5mm to suit if you use the WIMA

C707/708 - 3.3uf WIMA MKS2 or Panasonic stacked film capacitors or similar - you will need narrow lead spacing of 5mm to suit

C709/710 - 10uf WIMA MKS2 if you are keen and can source them, otherwise I'd suggest Nichicon UKL low noise caps  - you will need narrow lead spacing of 5mm to suit if you use the WIMA

C801/802 - install 1uf WIMA MKS2 or Panasonic stacked film capacitors or similar  - you will need narrow lead spacing of 5mm to suit

C817/818 - output coupling caps - go for 2200uf or 3300uf 35V to 50V caps here

 

Regarding the power supply filter caps, go larger where you can (generally one step up in capacitance, and either match or exceed the original voltage, but don't exceed 100V) as you might be able to get closer to the size of the originals. I'm pretty sure that some of the originals will have old-school lead pitch / spacings, and won't match the modern snap-in capacitor lead pitches. Some creative installation work and mods may be required (AKA drilling a tiny hole or two in the right place, having regard for the layout of the PCB traces to ensure you complete the circuit and don't short anything out in the process!)

Edited April 2, 2020 by pete_mac

[Spider27]

Opened the units and checked the solder joints and most of them look quite clean without cold solder. Control Amp Section looks clean.

Head Amp section looks clean. Main Amp had a few suspicious solder joints so re-soldered them. 

Powered on and right channel crackling noise still present. 

 

Next option is as suggested, recapping capacitors as well as exchanging 2SC871s -> BC550s...

 

Main Amp section before re-soldering. It has some suspicious joints that have been cleaned and re-soldered.

 

Control Amp section looks clean.

Edited April 2, 2020 by Spider27

[Spider27]

@pete_mac  Thank you very much for those info.

 

May I know where the best place to purchase those caps? Is https://au.element14.com/  best place to purchasing the caps?

 

Re: exchanging 2SC871s -> BC550s, do you mean replacing all of below locations with BC550?

 

Main Amp <F-1082>
TR801
TR802

Control Amp <F-1083>
TR701
TR702

Head Amp <F-1064>
TR601
TR602
 

I noticed that there are 3 different types of BC550. Any one of them are fine?
BC550CBU, BC550CTA, BC550CG

 

Re; power supply caps, C817  1000uf, 35WV for example, do you mean go for 1000uf caps between 35v and 100v such as this one (63v)?

https://au.element14.com/illinois-capacitor/108cke063m/aluminum-electrolytic-capacitor/dp/1666122?st=1000uf

 

Thank you again... 

[pete_mac]

23 minutes ago, Spider27 said:

@pete_mac  Thank you very much for those info.

 

May I know where the best place to purchase those caps? Is https://au.element14.com/  best place to purchasing the caps?

 

Re: exchanging 2SC871s -> BC550s, do you mean replacing all of below locations with BC550?

 

Main Amp <F-1082>
TR801
TR802

Control Amp <F-1083>
TR701
TR702

Head Amp <F-1064>
TR601
TR602
 

I noticed that there are 3 different types of BC550. Any one of them are fine?
BC550CBU, BC550CTA, BC550CG

 

Re; power supply caps, C817  1000uf, 35WV for example, do you mean go for 1000uf caps between 35v and 100v such as this one (63v)?

https://au.element14.com/illinois-capacitor/108cke063m/aluminum-electrolytic-capacitor/dp/1666122?st=1000uf

 

Thank you again... 

 

Element14, RS Components, Mouser and Digikey the way to go. 

 

Yes, those are the locations for the 2SC871 capacitors.

 

re: TA or BU, this refers to how they are supplied - on cut tape (TA) or loose bulk (BU). They are the same electronically.  The datasheets have useful info which explain this kind of thing. The G are no longer available.

 

Personally, I'd avoid those IC capacitors. Something by Panasonic, Nichicon, Kemet, EPCOS would be my choice eg:

 

https://au.element14.com/epcos/b41252a8228m000/cap-2200-f-63v-alu-elec-snap-in/dp/2468296?st=63V

 

C817/818 need to be upsized as I mentioned above -go for 2200uf or 3300uf. You will need to check the diameter of the originals to ensure that whatever you choose will fit OK. 

 

Upsize the other power supply caps too (C002 to C005):

 

C002 - 1500uf 63V to 2200uf 63V 

C003 and C005 - 500uf 35V to 1000uf 50V

C004 - 220uf 50V to 470uf 50V

 

The above will depend upon what you can find available. Going up a further step in voltage rating won't be an issue.

 

 

 

 

 

 

 

 

[Spider27]

Got BC550 transistors and replaced 2SC871s with BC550s on below locations.

 

Main Amp <F-1082>
TR801
TR802

 

Control Amp <F-1083>
TR701
TR702

 

Headamp section TR601 and 602 already have C945 transitors so did not replaced them.

 

The outcome is that crackling noise on right channel still present and there is no sound output at all.

 

 

[Spider27]

I think that I found the issue. The BC550 E/B/C configuration is different to 2SC871 after reading Datasheet. Need to take them out and resolder to correct configuration..  This is why it is important to check the data before rushing into action..... Fingers crossed and hope it works after redone.

[Monkey_Relish]

For the future, it is WELL worth it to purchase a Peak Atlas model DCA55 semiconductor analyser. Just connect to the transistor, press a button, and it tells you the pin out, as well as all the measured specs. I have been caught before getting ebc mixed up when using substitute transistors, but not since I purchased the Peak Atlas.
 

Mr Relish

[Spider27]

36 minutes ago, Monkey_Relish said:

For the future, it is WELL worth it to purchase a Peak Atlas model DCA55 semiconductor analyser. Just connect to the transistor, press a button, and it tells you the pin out, as well as all the measured specs. I have been caught before getting ebc mixed up when using substitute transistors, but not since I purchased the Peak Atlas.
 

Mr Relish

Great to know. Will look out for one and get one if I decide to do this often.  

[Spider27]

Just resoldered those transistors to correct pin out and I now get the sound out..

Crackling sound on the right channel has reduced (still there but less).

 

However, sound output level is noticeably less than previous.  (scratching my head)....

[Spider27]

Here is a quick shot between old transistor (2SC871) on the left and new transistor (BC550) on the right. The size is quite different. Not sure about the value... Is it possible that changing transistor change the sound output level substantially?

 

 

[Batty]

trust Pete_mac

[Spider27]

42 minutes ago, Batty said:

trust Pete_mac

Fully trust @pete_mac and other members who made suggestion on this thread. There is no trust issue there.

 

My question is if there are different types or sizes of BC550 to check if I got correct one. If it did, then what normally causes sound output level drop substantially?

 

I got the transistor from JayCar and here is the link for datasheet.

https://www.jaycar.com.au/medias/sys_master/images/images/9373003317278/ZT2160-dataSheetMain.pdf

[sloper]

Goodaye

 

Its still a BC550 just a  different package.

 

It took me 4 goes to get the pots of a AU222 clean once.

Check for cracked/dry solder joints with a magnifing glass.

Still could be a noisy transistor.

Amp was singing after l finished.

 

What area are you in?

 

regards Bruce

[Spider27]

Hello, @pete_mac

 

May I double check if BC550 is similar value as 2SC2240 and KSC1845? I noticed that you suggested the other two transistors for AU101 thread and just wondering if those 3 are all similar or AU101 and AU222 are two different amps so different transistors required? 

 

On 13/10/2019 at 3:08 PM, pete_mac said:

 

I'd suggest the above, although make sure you check the pinouts are correctly orientated before installation. 

 

If you have the 2SC871 transistors in the pre/phono stage etc, swap them with 2SC2240 or KSC1845.

 

[Spider27]

3 minutes ago, sloper said:

Goodaye

 

Its still a BC550 just a  different package.

 

It took me 4 goes to get the pots of a AU222 clean once.

Check for cracked/dry solder joints with a magnifing glass.

Still could be a noisy transistor.

Amp was singing after l finished.

 

What area are you in?

 

regards Bruce

Thank you for the info and great to know that I did not get wrong BC550. (relief)

 

I will do another thorough cleanup pots.

 

Re: checking cracked solder joints, any particular area (Main Amp, Control amp or Head Amp section) that I may need to look out for?

 

The crackling noise starting to coming back up after running about an hour this morning but not all the time but come and go.

 

I am based in west suburb (Werribee) of Melb.

 

Thanks again.

[pete_mac]

5 hours ago, Spider27 said:

Hello, @pete_mac

 

May I double check if BC550 is similar value as 2SC2240 and KSC1845? I noticed that you suggested the other two transistors for AU101 thread and just wondering if those 3 are all similar or AU101 and AU222 are two different amps so different transistors required? 

 

 

Correct - you can use any of those. As always, check the transistor pin-out configuration to ensure they are installed correctly.

 

It's very odd indeed that you now have a reduced output level - it doesn't make sense. Are you 100% certain that every transistor in installed in the correct orientation?

 

Likewise, it is odd that the crackling is still there. I'm assuming that you've replaced all of the small signal transistors on both the amp and preamp boards?

Edited April 4, 2020 by pete_mac

[Spider27]

18 minutes ago, pete_mac said:

 

 

Correct - you can use any of those. As always, check the transistor pin-out configuration to ensure they are installed correctly.

 

It's very odd indeed that you now have a reduced output level - it doesn't make sense. Are you 100% certain that every transistor in installed in the correct orientation?

 

Likewise, it is odd that the crackling is still there. I'm assuming that you've replaced all of the small signal transistors on both the amp and preamp boards?

 

Hi Pete.  I double checked pin configuration and yes, it is correct position now after initial mistake which cause no sound at all.

 

Actually, Headamp section TR601 and 602 already have C945 transistors instead so did not replaced them with BC550. However, I am not sure if headamp section would make difference for speaker out section.

 

Only thing that I have not done is replacing capacitors which I am still working out finding correct size and value. I was going to do that once crackling noise and volume output sorted out.

 

Maybe i am too novice after all and not cut out for this task  (my self-confidence level is dropping down rapidly now).

 

 

[aussievintage]

7 minutes ago, Spider27 said:

I double checked pin configuration and yes, it is correct position now after initial mistake which cause no sound at all.

 

 

I am wondering if one or more transistors were damaged when you had them soldered incorrectly and powered the amp on.     

[aussievintage]

9 minutes ago, Spider27 said:

Only thing that I have not done is replacing capacitors which I am still working out finding correct size and value. I was going to do that once crackling noise and volume output sorted out.

Crackling noises can be tricky to track down, even for experienced users.   I had a funny noise that eventually turned out to be just a loose RCA connector.    Old amps need a thorough cleaning and it can take a couple of cleans to silence switches, pots and connectors.

11 minutes ago, Spider27 said:

Maybe i am too novice after all and not cut out for this task  (my self-confidence level is dropping down rapidly now).

Do not give up.  The fact that you have been able to swap out transistors shows you can do it.  We've all put a transistor in wrong before, I am sure.

[aussievintage]

13 minutes ago, Spider27 said:

Only thing that I have not done is replacing capacitors which I am still working out finding correct size and value. I was going to do that once crackling noise and volume output sorted out.

Had another thought - I am not sure, but I think I have heard crackly noises from bad caps, but it may have been just a bad solder joint on one.