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Sansui AU-222 Restoration by Total Novice


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1 minute ago, audiofeline said:

I've been reading this thread and have a degree of admiration that you are tackling this - I feel it's one step beyond my novice skills!  I'm pleased to see you have persisted through this challenge,  as this is what develops competence and knowledge.  Good luck with the rest of the restoration. 

Thank you for your kind word and encouragement. If COVID-19 lockdown was not in place, I would have been given up already.  Since I have some spare time, I am doing this but it is still not progressing into positive way or improving from current status as yet ?

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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

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

Good, man, I hoped you wouldn't give up on this.  



29 minutes ago, Batty said:

Will we see this in the classifieds soon Spider?

I am not evening thinking that far. My sole focus is making this work without crackling noise coming and going which is very annoying and unpleasant whenever I power it on and try to listen.

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2 minutes ago, Batty said:

Good, man, I hoped you wouldn't give up on this.

 

We will see the outcome either making it work and enjoy listening with it with big smile or fail miserably and wasting money and time on this and weeping at the corner of my room soon....

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On 17/04/2020 at 2:23 PM, pete_mac said:

Sorry @Spider27… still working on that darn report. Let me see what I can do later tonight. :)

Hi Peter. Have you had a chance to check those 9 capacitors by any chance?  No urgency... It just has been 7 days waiting and not sure if I just should proceed placing an order to see how it goes or wait for your confirmation before proceeding. 

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9 minutes ago, Spider27 said:

Hi Peter. Have you had a chance to check those 9 capacitors by any chance?  No urgency... It just has been 7 days waiting and not sure if I just should proceed placing an order to see how it goes or wait for your confirmation before proceeding. 

 

No closer unfortunately - work has been consistently busy.

 

Provided that you have double-checked your list against what is actually physically installed in your amp (there can be variations during production runs and improvements to the design over time) then you should be OK. This also gives you the opportunity to measure the diameter of the current caps and ensure there is space for the new caps that you've chosen, and to get a feel for the lead spacing of the original capacitors vs the ones you've chosen (I have no way of doing this remotely). I'd particularly check the 3.3uf film cap - is it a 5mm lead spacing? If not, it definitely won't fit.

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As a person interested in tackling a job like this myself, I watch with great interest! I have to date only serviced turntables and clean outs on electricals. As soon as the soldering iron is called up i wuss out! Good luck!

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On 24/04/2020 at 10:44 AM, pete_mac said:

 

No closer unfortunately - work has been consistently busy.

 

Provided that you have double-checked your list against what is actually physically installed in your amp (there can be variations during production runs and improvements to the design over time) then you should be OK. This also gives you the opportunity to measure the diameter of the current caps and ensure there is space for the new caps that you've chosen, and to get a feel for the lead spacing of the original capacitors vs the ones you've chosen (I have no way of doing this remotely). I'd particularly check the 3.3uf film cap - is it a 5mm lead spacing? If not, it definitely won't fit.

Thank you. I checked the size and the 3.3uf film cap would not fit and found the alternative one. However, element14 only sells 10 as one lot quite expensive. I will checked the other sellers if they sell individually.   The other caps' size seem all ok.

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Just before placing an order for the caps online, I tested the amp again by turning on low, high filters and loudness buttons this evening and when those buttons are pushed, loud crackling sound came up on left channel and left channel is now silent without sound. ?

 

I might need a doctor to have a look first before recapping the amp and making diagnosis of the issue harder. ?

 

Does anyone know who repairs vintage amp in victoria? If the person is SNA member, it would be even better.

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8 minutes ago, Spider27 said:

I tested the amp again by turning on low, high filters and loudness buttons this evening and when those buttons are pushed, loud crackling sound came up on left channel and left channel is now silent without sound. ?

 

If you are sure the switches  and any connectors etc are all clean, then I am starting to suspect a circuit board problem.  A cracked trace, maybe heat damaged with repair work, or just a bad solder joint being stressed by physical vibrations.

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1 hour ago, aussievintage said:

Meant to add, can you provoke crackling etc by tapping on the circuit board in various places, or even tapping on wires and other things inside?

Spot on.. When I tap the power amp board, it does not make difference but when I tap preamp board, it make loud pop sound on left channel. 

And, still no actual music sound coming out from left channel... 

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OK it's cracked track, bad solder joint or something like that.  You may be able to localise it by tapping lightly on different parts of the board and components, then it's visual inspection and resoldering.  

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Greetings from the other side of the world from  Birmingham, Blighty! I just noticed this thread as I too have been doing _*exactly the same thing*_ (great minds etc), by attempting to fix my own Sansui AU-222 as a project for me while being part of the covid19 lockdown, the latter of which is just nuts- so stuck indoors, 24/7, what else can a bloke do...? It's 11.41pm here now and I really must go to bed, but one of the fixes for the problem of weird popping/crackling sound is highly likely to be, and after hunting through literally hundreds of pages on Audiokarma and DIY Audio is that the four trim pots on the main board F-1082A get badly oxidised and need swapping out for new trimpots.

Make sure though before you do this to get a reading with your ohmmeter to the exact settings with the existing trimmers (if possible- mine on the left channel is all over the place), write them down, then with the new trimmers, dial them in before resoldering to the main board. Then follow the instructions with ammeter and scope- with 8Ω load over the outputs. This means that the current/signal won't be wildly out- and may fry another component while swapping in/ around. I hope that makes sense? I believe the four (two of each) trimmers are 220Ω and 200kΩ respectively. It could also explain why tapping on the board has an effect. because the bad connection is in those ancient 50 year-old trimmers. 

BTW, Your board looks in real nice shape! I can see the original copper! Mine is completely shagged. Some fool from the past has covered the whole thing in solder, which I presume was done to prevent all the trace lifting from the underside. My board was in such bad shape (output transistors and 2SC815's/281's etc had been 'space wired'!), that I've replaced the old board completely (press n peel'ed), and then taken many of the old components off in order place them back on the new board. I know some would disagree with this, and would state that it isn't worth it, but I disagree. The Sansui AU-222 is one of the finest sounding amps from Sansui bar none (sorry guys, but it's true!) Worth every effort to get it fixed. 

I'll talk some more tomorrow, but I'm now going to retire for the night. 

Cheers!

 

Tom

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22 hours ago, tom_tm said:

Some fool from the past has covered the whole thing in solder, which I presume was done to prevent all the trace lifting from the underside.

Or there was a crack in the copper somewhere that they couldn't find, so they soldered the lot.  It may well have cured the problem :) 

 

 

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Hey Spider27,

Been reading through your thread with optimism, I also have an AU-222 that is mostly original. 

I've seen Petemac offer his wisdom but seems like he has a lot on his plate during this time, I'm fairly untied with commitments ATM so don't mind answering your questions to get this amp sorted.  In fact if you want to call me we can share more info quicker and I'll be up to speed.  Ben :)

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3 minutes ago, Benji_man said:

Hey Spider27,

Been reading through your thread with optimism, I also have an AU-222 that is mostly original. 

I've seen Petemac offer his wisdom but seems like he has a lot on his plate during this time, I'm fairly untied with commitments ATM so don't mind answering your questions to get this amp sorted.  In fact if you want to call me we can share more info quicker and I'll be up to speed. Ben :)

Thank you so much for your kind offer. :) You may want to delete your phone number on public forum and send the number via Private message instead to avoid spam and possibly voice phishing. I believe that this forum does not recommend leaving contact number on public forum section.

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On 28/04/2020 at 8:53 AM, aussievintage said:

OK it's cracked track, bad solder joint or something like that.  You may be able to localise it by tapping lightly on different parts of the board and components, then it's visual inspection and resoldering.  

Another method I used to use, was blowing cool air from a compressor at low pressure and careful localisation, to find dry joints/cracks etc. It will often show up components that may be on their way out, but work OK when warmed up.

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A few insights from my experience restoring many Sansui AU series.

Most amps of this age, depending on how well they've been looked after, need need a fair bit of general housekeeping to eliminate many common faults before looking further. e.g. re-working dry solder joints, cleaning and re-lubing contacts and switches, even rejuvenating fuse holder connections.

Electrolytic caps usually need partial or full replacement as the smaller caps particularly are often way out of spec. Larger value caps tend to survive much better and are often still well within tolerance.

This will clear the way to identify other issues.

The source of crackling on is more often than not smaller transistors playing up, if you've already eliminated dirty switches, pots or dodgy solder joints. 

When sourcing substitute transistors for Sansuis, take careful note of transistor pin configurations, they can often be different, reversed etc. Check and re-check your work and be patient to avoid mistakes.

 

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l will admit getting caught out on reverse pin configurations, only once.

Kick myself for selling the AU222 after restoring it, but l did trade up to a AU70 so its not all bad.

From memory l used a lot of KSA1845's on the tone board and modded it much the same as my AU505's

 

regards Bruce

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On 27/04/2020 at 8:21 PM, Spider27 said:

Thank you. I checked the size and the 3.3uf film cap would not fit and found the alternative one. However, element14 only sells 10 as one lot quite expensive. I will checked the other sellers if they sell individually.   The other caps' size seem all ok.

 

Nice one - glad you caught this beforehand! I've been down that path before re: incorrect lead spacing. One bitten, twice shy!

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  • 8 months later...
On 04/04/2020 at 9:21 PM, Spider27 said:

 

The crackling noises are still there though.  

 

The crackling noise is common problem of vintage gears. The problem is The oxidation coming along pins into the transistor.  

Try to take out a right channel transistor and then install it to the same spot of left channel.   Then left channel transistor installs to the right one. Listen either defect is moved to other channel or not and so on. 

Another transistor check in the circuit.  If the voltage between the emitter and the base is 0.6V transistor is opened/good. 

This one is handy:

https://www.ebay.com.au/itm/TFT-LCD-GM328-Transistor-Tester-Diode-LCR-ESR-Meter-Protective-Cover-N9V2/203175609628?hash=item2f4e35c51c:g:wNMAAOSwSAtfqrR5&frcectupt=true

Edited by olegau
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On 27/04/2020 at 8:25 PM, Spider27 said:

I might need a doctor to have a look first before recapping the amp and making diagnosis of the issue harder. 

I used to be an electronic repair tech. When you have time come down to my place in St Kilda.  

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