Sansui AU-317 vs. AU-317 Mk-II

[AUD101]

Check out this posting from forum member pete_mac regarding mains cable replacement on an AU-719 which maybe possible on your AU-317 - http://www.audiokarma.org/forums/showpost.php?p=5446732&postcount=60

 

[Karl vd Berg]

Hi Karl,
Here is a link (Australian audio forum) to a 317 restoration I did earlier this year

http://www.stereo.net.au/forums/index.php?/topic/44937-sansui-au317-restoration/

Cheers

John

Hello John,

Just a couple of questions before I close the unit.

1. You mentioned here (between 2nd and 3rd pics) that "Along with the recap of the this board, the differential input pair transistors for each channel were also replaced with low noise gain matched pairs. The initial checks/tests I did showed some pop/crackle/noise in the left channel when the phono input was selected, and some minor noise was evident in the right channel. Replacement of the input pairs fixed this."

Since I don't use turntables (maybe again in the future...), shall I worry about these transistors?

2. I'm ready to put the Bourns VRs for the bias adj. It's a 3 pin which I believe the mid pin should go in the "common" point, right? Or is there a position like the screw down the board?

Thank you! :thmbsp:

 

[Karl vd Berg]

Check out this posting from forum member pete_mac regarding mains cable replacement on an AU-719 which maybe possible on your AU-317 - http://www.audiokarma.org/forums/showpost.php?p=5446732&postcount=60

Hi AUD101,

Thanks for the link!

I'll hook the normal mains to the amp, leaving the ground out. Most Japanese manufacturers never grounded their gears in those days (Seventies)... :thmbsp:

 

[skippy124]

Hello John,

Just a couple of questions before I close the unit.

1. You mentioned here (between 2nd and 3rd pics) that "Along with the recap of the this board, the differential input pair transistors for each channel were also replaced with low noise gain matched pairs. The initial checks/tests I did showed some pop/crackle/noise in the left channel when the phono input was selected, and some minor noise was evident in the right channel. Replacement of the input pairs fixed this."

Since I don't use turntables (maybe again in the future...), shall I worry about these transistors?

2. I'm ready to put the Bourns VRs for the bias adj. It's a 3 pin which I believe the mid pin should go in the "common" point, right? Or is there a position like the screw down the board?

Thank you! :thmbsp:

Hi Karl,

If you are not going to use the phono inputs then it is not necessary to replace the transistors (nor would it be necessary if there was no pops/crackles noise form the speakers with the phono input selected).

With regard to the bias pots, you are right, the mid pin of the bourns pot is the wiper. I suggest that you measure the resistance value of the old pots in circuit and then adjust the new pots (in circuit) to a similar value plus 10 to 20 ohms. For orientation, go with the orientation I had in the thread you linked, the right hand one has the screw oriented to the outer side of the amp, the pot in the middle of the board has the screw oriented to the front of the amp.

Cheers

John

 

[Karl vd Berg]

Clear! :thmbsp:

Thank you again!

 

[Karl vd Berg]

One last things, my friends!

The DC Offset for the AU-317...

Since the Bias adjustment has to be done AFTER the DC Offset, and the latter has to be done with TWO trimpots per each channel (VR01 > 2k2 and VR03 > 100 ohms for the Left channel; VR02 > 2k2 and VR04 > 100 ohms for the right channel), how does it proceed?

Which of the first two pots has to be measured, the VR01 first and then the VR03 after or vice-versa?

And does it have to be exactly 0 VDC?

Thanks!

 

[Karl vd Berg]

The amplifier is finished but with terrible results! :worried:

I did all the replacements, the sound is just crappy.

The balance doesn't work. When I turn to the left it seems to go in mono. Turning to the right there's a fading sound. Bass and Treble work well.

I don't know if because all the components are new and have to warm up for few days, but definitely something is wrong...

 

[pete_mac]

D'oh! If this problem was not there before the recap, then something has gone wrong. Double-check the polarity of all capacitors. Did you cut/desolder any wiring? If so, double-check these too.

 

[skippy124]

Can you take some photos of the main Power amp PCB particularly where the wires are connected (the ones that you disconnected when removing the main PCA.

Also as Pete said, recheck the polarity of all the caps that you replaced, and check the orientation of any other components like diodes and transistors that were replaced (if any).

We you able to set the offset and bias?

Cheers

John

 

[Karl vd Berg]

D'oh! If this problem was not there before the recap, then something has gone wrong. Double-check the polarity of all capacitors. Did you cut/desolder any wiring? If so, double-check these too.

Yes, I put all the wires in the back side. I did that to have to work better.

 

[Karl vd Berg]

We you able to set the offset and bias?

Cheers

John

No, I wasn't. I'll check everything again before I switch it on again.

The only thing is that if this amp had already some problem before recap...

 

[Kale]

Hi folks!

Which one shall I take? Is the second version (Mk-II) much that better than the first?

Those AU317 amplifiers (first and second model) are the best small amplifiers which I ever seen and heard! They are really great, especially if you can buy them under 100EUR.
But there are some differences between those two models, an I would like to say that first model is better quality than second;
- first model has black anodized aluminum heat sink, second has nature anodized aluminum (black is better)
- as pete_mac said... The early model also has the pre-out/main-in connectors on the rear panel
- first model has better quality RCA connectors (second model has RCA connectors like AU919 or AUX1 which can be rusty after so many years)
- first model has the power transformer totally shielded
- I am not 100% sure, but I think that AU317 has aluminum knobs, but I am sure that AU317II has plastic.
- AU317 has lower voltage power supply of main amplifier (so because of that you can change two main power supply capacitors by Nichicon Gold Tune 10000uF 50V, but you cannot replace those power supply main capacitors on AU317II with the same capacitors because of 48V supply)

Not big differences but as I said, better to me is AU317 first generation.

 

[Kale]

LOL!



There are the 2 couple of transistors (2nd pic) they look very scruffy (2SB527 and 2SD357). Kale, on the beautiful thread "AU-X1 Japanese restoration unit" mentioned that he changed these TRs for other ones with greater Vcbo.

I wonder if other transistors in the AU-317 (TR601 and TR602), 2SD356 and 2SB526 (3rd pic), should also be replaced with new ones or with greater Vcbo as well.

That I did on AUX1 because AUX1 is very high speed amplifier and I would like to be sure that anything will not cause any kind of problem, so I replaced those 2SB527 2SD357 by 2SB528 2SD358. Here I must say that 2SB528 2SD358 is hard to find today, so there are no need to replace those 2SB527 2SD357 on yours AU317 (normally if they are OK)

 

[Kale]

Here on AK, I have one thread about one AU317 restoration: http://www.audiokarma.org/forums/showthread.php?t=234181 but what is interesting, I am currently working one restoration on AU317II, but now I am not at my home, so I cant show you any picture, but I will when I will be at my home at Friday.

 

[Kale]

The amplifier is finished but with terrible results! :worried:

I did all the replacements, the sound is just crappy.

The balance doesn't work. When I turn to the left it seems to go in mono. Turning to the right there's a fading sound. Bass and Treble work well.

I don't know if because all the components are new and have to warm up for few days, but definitely something is wrong...

I'm sorry that the amplifier is not working as it should be, but it must have great sound when all is OK.
During my restoring jobs, I have seen so many kind non specific problems, like not good ceramic capacitors (oscillations), transistors which are good on diode test, but bad when you apply voltage supply, fusible resistors (changed value), zeners with wrong zener voltage....

Here I must say you something, when you changing some element (like capacitor), you should check how old was connected and put a new one on the same way! Why I am saying that, because I have seen so many times wrong marking on PCB boards, that is something what you can find very often on Sansui boards.
The same is with schematic diagrams, you should be very careful about that.
And finally I like to say that reccaping is simple job when you got the good result, but if things go on wrong way, than you should have more test equipment than DMM especially you should have an oscilloscope, without oscilloscope you cant see oscillation or some other kind of specific problem.

 

[Karl vd Berg]

I'm sorry that the amplifier is not working as it should be, but it must have great sound when all is OK.
During my restoring jobs, I have seen so many kind non specific problems, like not good ceramic capacitors (oscillations), transistors which are good on diode test, but bad when you apply voltage supply, fusible resistors (changed value), zeners with wrong zener voltage....

Here I must say you something, when you changing some element (like capacitor), you should check how old was connected and put a new one on the same way! Why I am saying that, because I have seen so many times wrong marking on PCB boards, that is something what you can find very often on Sansui boards.
The same is with schematic diagrams, you should be very careful about that.
And finally I like to say that reccaping is simple job when you got the good result, but if things go on wrong way, than you should have more test equipment than DMM especially you should have an oscilloscope, without oscilloscope you cant see oscillation or some other kind of specific problem.

I really don't know what happened, but I have the feeling that it was not my restoration reccaping for this amp. All the problem seems to rely on the Tone control board which had the same problem when I got it. I carefully checked every single component I changed, from capacitors to series'd diodes, etc...

If there is something on the Tone control board (I want to believe the issue relies there), must be some transistor or diode that gone bad, but I don't know.

I'm really disappointed. I was (and still am) really looking for this particular model. No way to give to any technician, but only Sansui experts.

 

[Karl vd Berg]

More pictures...

 

[AUD101]

Sorry to hear your AU-317 is not working as it should - :tears: - From the pic's you have posted of Power Amplifier Board – F2754 - (2nd pic above)
The DC-Offset trimmer presets VR01 & VR02 are marked as "W102" which is 1k - This should be "W202" (2k) .......and
The BIAS trimmer presets VR05 & VR06 are marked as "W202" which is 2k - This should be "W102" (1k)

It would seem that you have put in the wrong pair of trimmer's in the wrong place - you need to swap them

 

[Karl vd Berg]

Sorry to hear your AU-317 is not working as it should - :tears: - From the pic's you have posted of Power Amplifier Board – F2754 - (2nd pic above)
The DC-Offset trimmer presets VR01 & VR02 are marked as "W102" which is 1k - This should be "W202" (2k) .......and
The BIAS trimmer presets VR05 & VR06 are marked as "W202" which is 2k - This should be "W102" (1k)

It would seem that you have put in the wrong pair of trimmer's in the wrong place - you need to swap them

You're right!! :yes:

Just swapped them. Put the speakers again and now I have the following thing: only the left channel works. But when I switch the Loudness on, I hear some sound on the right channel but not that much, and only high frequencies. Checked all the caps and diodes I replaced and they are correct. The power caps have 43.85 VDC both channels.

Master volume distorts a lot when turning a bit up...

One more thing, the Tape Monitor switch should block the Line AUX when it goes from "Source" to "Tape", right? Well, nothing happens when I turn it up or down. Line AUX continue to play normally...

 

[Alienz]

I hope you can get it fixed Karl, I messed up the recap of my AU-3900, had me spooked for weeks. In the end it was all my own fault, I put in a wrong diode Never would have found out if it wasnt for the helpfull people here on AK
So hang in there, sometimes you just need a break and let things sink in.

Gerard