Thank you for the peace of mind on that. Now I'll be working on a parts order and making sure my 555 doesn't need any repairs before I start the restoration/upgrade.
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Leestereo's Restoration/Upgrade of a Sansui AU-555A
zeste
New Member
@ JimEGR : You are welcome!
Here is the AU555a that join his brothers
. The amp has a temporary green lever knob. It is a print test that work. I will see if will print a silver one or if I can made one from a pipe.
I connected it to my main speakers the Tandberg.
A friend came last week-end to listen to my new amplifier, he is more a Naim guys, but he like the sound and that the amp is fast and dynamic. I told him that something bother me. I didn't know how to explain that. It was like there is too much bass sometimes. After a couple of minutes of listening he agreed with me.
So he decided to play with the settings of bass and tremble. He set the bass at -2 and the treble at -2. And it was very fine. Since, I listen with this setting and it is a more natural sound.
I'm very happy with this amp and I would like to thank again @Leestereo for the mods that he shared !
Here is the AU555a that join his brothers
. The amp has a temporary green lever knob. It is a print test that work. I will see if will print a silver one or if I can made one from a pipe.I connected it to my main speakers the Tandberg.
A friend came last week-end to listen to my new amplifier, he is more a Naim guys, but he like the sound and that the amp is fast and dynamic. I told him that something bother me. I didn't know how to explain that. It was like there is too much bass sometimes. After a couple of minutes of listening he agreed with me.
So he decided to play with the settings of bass and tremble. He set the bass at -2 and the treble at -2. And it was very fine. Since, I listen with this setting and it is a more natural sound.
I'm very happy with this amp and I would like to thank again @Leestereo for the mods that he shared !
@ JimEGR : You are welcome!
Here is the AU555a that join his brothers
I connected it to my main speakers the Tandberg.
A friend came last week-end to listen to my new amplifier, he is more a Naim guys, but he like the sound and that the amp is fast and dynamic. I told him that something bother me. I didn't know how to explain that. It was like there is too much bass sometimes. After a couple of minutes of listening he agreed with me.
So he decided to play with the settings of bass and tremble. He set the bass at -2 and the treble at -2. And it was very fine. Since, I listen with this setting and it is a more natural sound.
I'm very happy with this amp and I would like to thank again @Leestereo for the mods that he shared !
View attachment 2846440
Very nice looking collection! What are the three other Sansui’s there? I preferred my tone controls flat after my AU-555a restoration. Typically flat on all of my pieces, actually. And Loudness off. Curious if you tried the Mid tone control? Pretty unique having that third tuning dimension. I’ve found the speaker/placement/room has a large influence on the sound characteristics. Took me some time to find the speaker(s) and placement and room treatments that work best with my gear (and ear). I found Klipsch and Zu Audio speakers delivered the most balanced, honest and transparent sound qualities - “natural”. ADS the most fun
. Boston Acoustics most warmth. My favorites out of what I’ve tried. What speakers are you using?
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zeste
New Member
Left up is the AU777d, left down is the AU111 and right down is the AU999. On all this amp and the other Sansui I have, the tone set flat too with the same speakers.
I use the Tandberg TL3520 which are 3 ways closed speaker. They are very versatile and perform well with other amp I have recapped (Naim net 5, rega elex, harman kardon HK505 and A402).
They provide a warm and rich sound.
The Tandberg have the same position when I use the AU777d/AU111/AU999 and I don't have to play with the tone.
Perhaps, the fact I put 6800uF coupling caps increase lower the low pass filter. I think Leestereo mention this point one of his post.
I use the Tandberg TL3520 which are 3 ways closed speaker. They are very versatile and perform well with other amp I have recapped (Naim net 5, rega elex, harman kardon HK505 and A402).
They provide a warm and rich sound.
The Tandberg have the same position when I use the AU777d/AU111/AU999 and I don't have to play with the tone.
Perhaps, the fact I put 6800uF coupling caps increase lower the low pass filter. I think Leestereo mention this point one of his post.
Thanks for the review. And what an excellent collection of Sansui All Stars!
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siriogenoa55
New Member
Hi Leestereo, meanwhile thank you for your precious guide. I acquired this marvelous amplifier and proceeded to replace all the electrolytic capacitors (not C819 and C819 which seem good to me) and the cdc9002 transistor (interrupted) which I replaced with a BC640. Incidentally the main amplifier board is F-1266-1. I got the bias adjustment correctly while I have some doubts about the balance adjustment (output adjustement). I followed the procedure described in the Service Manual, turning up the volume and adjusting the trimmers, I get a flattened sine waveform on both sides, but the line in the upper part is not as clear as in the lower one and appears flickering. I don't know if the phenomenon can be clearly seen in the photo. Is there any reason for this?
Thanks for the replies
Frank
Thanks for the replies
Frank
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Thanks @Leestereo
Good morning!. I have followed the step-by-step restoration of this thread and the sound of the equipment was fantastic, thank you all for sharing your experiences!!!! I think it is my best vintage in terms of quality.
The only difference is that in the source capacitors use higher values, for example use 6800 instead of the original 470.
The sound is noticeably better, so much so that it is not necessary to use the loundness button. However, I have another Sansui, an 881 that I made more or less the same improvements but if I don't use the loudness button the sound is flatter.
How can I improve bass and treble to avoid the loudness button?
I apologize that the question is for another thread.
Thank you
Good morning!. I have followed the step-by-step restoration of this thread and the sound of the equipment was fantastic, thank you all for sharing your experiences!!!! I think it is my best vintage in terms of quality.
The only difference is that in the source capacitors use higher values, for example use 6800 instead of the original 470.
The sound is noticeably better, so much so that it is not necessary to use the loundness button. However, I have another Sansui, an 881 that I made more or less the same improvements but if I don't use the loudness button the sound is flatter.
How can I improve bass and treble to avoid the loudness button?
I apologize that the question is for another thread.
Thank you
JRH99
Active Member
I restored my Sansui AU-555A to @Leestereo recommendations about a year and a half ago, and have been enjoying it ever since.
Unfortunately I had a recent power surge that took out several of my electronics including my DAC, a power supply for my DVR, a network hub, and my beloved Sansui AU-555A
. Since the power surge (lighting strike nearby), the Sansui has a distorted right channel. I put it back on the bench and see no obvious signs of damage. I am going to need some help on troubleshooting this. Any advise / thoughts on what I might check for would be appreciated.
Unfortunately I had a recent power surge that took out several of my electronics including my DAC, a power supply for my DVR, a network hub, and my beloved Sansui AU-555A
. Since the power surge (lighting strike nearby), the Sansui has a distorted right channel. I put it back on the bench and see no obvious signs of damage. I am going to need some help on troubleshooting this. Any advise / thoughts on what I might check for would be appreciated.
The Fuxtor
Addicted Member
Check the fuse... I've had distorted sound from a bad one before. It looked ok, but when I changed it the distortion was gone.I restored my Sansui AU-555A to @Leestereo recommendations about a year and a half ago, and have been enjoying it ever since.
Unfortunately I had a recent power surge that took out several of my electronics including my DAC, a power supply for my DVR, a network hub, and my beloved Sansui AU-555A
JRH99
Active Member
Thanks, I swapped the output fuses and problem is still in right channel.
Lazarus Long
Super Member
That really sucks. If there isn’t any obvious damage, you will probably have to trace it down with a scope.
@JRH99: If you cross-connect the preamp-out and main-in, i.e., left channel pre-out to right channel main-in and right pre-out to left main-in, you can determine if the problem is in the preamp stage or the main amp stage. If the right channel still has distortion, the problem is in the right channel main amplifier; if the problem is now heard in the left channel, the problem is in the right channel of the preamp stage.
JRH99
Active Member
Thanks for the feedback. Cross connected the pre/main and still have distortion in the right channel. So this indicates main amp right channel issue, correct? So without a scope, is there a best place to start a process of elimination, or likely suspects? Or, is it time for me to get a scope?
Is the sound on the right channel distorted when using headphones?
JRH99
Active Member
Yes, but not as bad as the speaker. The speaker is completely distorted and breaking up on right. I hear the distortion on the right side headphone, but it not as broken up as the speaker.
JRH99
Active Member
just tried both ways and the right headphone is much more distorted with the speakers are on.
JRH99
Active Member
I pulled all four of the 2SC1030 transistors and tested them using the diode mode on my DMM, all check ok with that test. I followed the process outlined by EchoWars, and if I am understanding correctly, passing this test does not mean that the transistor is not "leaky"? Would it be recommended to swap the left set to the right side and see if the distortion follows the set, or could that cause any potential problems with working channel?
Or, is the next step to just replace the 2SC1030? Do you recommend I replace as a set, just on the right channel? Any recommendations for replacements? I see in the past at MJ21194 was recommended, but it appears to be out of stock at Mouser.
The driver transistors in the SM, and what I see on the board are the 9002-1 and 8002-1. I see that KSC2383 and the KSA1013 have been recommended as replacements.
I have these on hand, would you recommend I just replace any failed parts I find, or just proceed to replace them all(right and left channel)?
A noisy transistor may well pass the diode check test. An oscilloscope may help. Here's how a noisy/distorting transistor looked on my scope. Note the thicker yellow trace at the bottom of the sine wave. I did swap the output transistors from left to right on this amp to verify the problem was in the output transistors. That glitch on the bottom of the blue trace was due to an arcing resistor so you can ignore that.
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