Sansui AU-X11 Restoration

Wow! I missed a lot. Holiday time does that.

Well...
1st...Yes, this is indeed a substitution only a knowledgeable tech would do. (AND this is great info to know as it confirms an optional way forward previously floated.)
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2nd. This is normal. These selector switches were used in other Sansui amps too.
The X11 doesn't use those prongs / channel selector positions, but an 907 or a 607 might.
I have the same on my X11s.
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3rd. Surprise indeed. There are supposed to be "black flags" on this driver board. (The drivers on my junk X11 has them and my good X11 as well.)
The tech who serviced that unit has saved you some time and effort.
He went in deep. (I wonder why?)
Leave the styrene caps in. They will live forever as long as you don't melt them.
Just make sure to clip heat shunts to their leads if you are doing any soldering around them.
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Over all you are very lucky. I think recapping the unit has been made somewhat easier for you by the work done by the previous tech.
Still a lot to check and replace, but less than normally required I think.

Really, I think all you need is...
  • just a thorough cleaning of all switches, selectors, and potentiometers
  • a replacement of all relays and trimpots
  • a fresh application of thermal grease
  • recapping (Kind of maybe? As long as you are in there?)
Keep it coming!
 
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There is a factory mod done , on board F-3460.
See the cuts in the PCB, just beneath the 6 big capacitors, probably mine is an older version of the Sansui X11, and the PCB has went through couple of changes.
I have never seen these cuts in the X11's worked by others.
DSC_0213.jpg
The cuts are just above the text SANSUI, and yes i have removed the 6 big capacitors and the holes are evident in the above picture.
The de-soldered joints, which have black heat marks, are the ones are the terminals removed to pull out the driver board, there is also the glob of solder near pre-amp signal input which i was talking about, you can see the mess in above picture.

A more better picture of the driver board F-3460 with 220uF 80V capacitors removed.
DSC_0214.jpg
 
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Time to finish the documentation process:

So, to remove the driver board completely the below wires need to be removed.
This process is optional, you can work by flipping the driver board, but then i feel its safer to have these wires removed.
Be careful, there are two white wires ( out of which one from the emitter is wired to the test points ).
DSC_0224.jpg
DSC_0226 - Copy.jpg

Pin 7 - Red wire, you can see this wire leads to a metal plate, this is where the red wire from the power supply caps come.
Pin 14 - Blue wire, the blue wire from power supply capacitors, are attached to the plates where the blue wire leads.
( Both these wires carry a positive and negative 68volts supply from the power supply capacitors, but i dont remember which is which now).
I am guessing the blue wire to be -68 volts and the red wire to be +68volts, i did measure the voltage across the power supply capactiors prior to removal, but i some how missed to note down the colors and voltages across them.
Pin 9 yellow and Pin 11 white leads to the different transistor pairs ( Pin 9 to NPN pair and Pin 11 to PNP pair respectively)

Pin 10 and Pin 12 on the PCB, are wired to bias test points as illustrated.

In case the wires come off while working on the board with them connected it will be useful to put them back in the right place.

Precautionary measure.

Transistors removed and the heat sink has been cleaned from existing thermal grease, this part is easy, i just used a microfiber towel to wipe it off.
There were no washers installed in the transistor mount screws and i could see small scuff marks in one of them.
DSC_0238.jpg
Yes two of the screws are missing, i have removed them as they were bent in multiple direction's when they were initially screwed in.
The bents were so prominent when removed, so i decided to get better screws and some washers to be used for mounting them back.

Measurement for the original outputs will be posted in some time.
 
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Sansui NMC1718
NPN Silicon BJT
Red-C Green-E Blue-B
hFE=76 at Ic=5.00mA
Vbe=0.610V at Ib=5.00mA
VceSat=0.019V at Ic=5.0mA and Ib=1.00mA
IcLeak=0.000mA
upload_2017-12-25_20-0-21.png

upload_2017-12-25_20-0-32.png

upload_2017-12-25_20-0-49.png

upload_2017-12-25_20-0-57.png

upload_2017-12-25_20-1-4.png

Sansui NMA1718:
PNP Silicon BJT
Red-E Green-C Blue-B
hFE=63 at Ic=4.99mA
Vbe=0.583V at Ib=5.00mA
VceSat=0.060V at Ic=5.0mA and Ib=1.00mA
IcLeak=0.000mA

upload_2017-12-25_20-8-59.png

upload_2017-12-25_20-9-10.png

upload_2017-12-25_20-9-16.png

upload_2017-12-25_20-9-25.png

upload_2017-12-25_20-9-31.png

I have a very very faint idea on what these graphs mean, will probably run a trace along with On Semi transistors and see how they perform compared to original outputs .
I am yet to work on interpreting the graphs.
Have plotted these manually when I was in college but now I have lost touch as I work on software development .
All the stuff I read about in college is being practically used now.
Downloaded some e-books to learn the basics again.
 
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There is a factory mod done , on board F-3460.
See the cuts in the PCB, just beneath the 6 big capacitors, probably mine is an older version of the Sansui X11, and the PCB has went through couple of changes.
I have never seen these cuts in the X11's worked by others.

This is visible on my AU-X11 driver board pics posted here. Excellent continued work on the documentation - keep it up!
 
This is visible on my AU-X11 driver board pics posted here. Excellent continued work on the documentation - keep it up!
Thanks for your reply.
I should have went through your build again before posting.
By the way i have a silly question, regarding the resistors that are present in the board and the ones that are used for replacement.

There are three different types of resistors used in the driver board.
1. Non Inflammable Resistor -> these are replaced by metal film resistors right ? Correct me if i am wrong.
2. Metal Film Resistor->Replaced by metal film resistors that are available
3. Cement Resistor -> Replaced by wire-wound resistors

Resistors.jpg

And the rest of them shown in above picture are carbon film resistors right.
Please let me know your suggestions, and also any specific brand or company which i could choose for the replacement.
Thanks again for helping me out.
 
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There is a factory mod done , on board F-3460.
...I have never seen these cuts in the X11's worked by others.
...The cuts are just above the text SANSUI, and yes i have removed the 6 big capacitors and the holes are evident in the above picture.

Whoa!
I thought that ALL X11s had that factory mod on the F-3460 PCB
Seems that some don’t after all.

It turns out that the F-3469 from my burned up X11 DOES NOT HAVE THAT modification.

This is a rather huge difference, and likely explains why one of my X11 got toasted while the other still operates today.

Now...What are the mods and how can you apply them to an older X11?

The X11 story just got complicated.

Sansui NMC1718
NPN Silicon BJT
Red-C Green-E Blue-B
hFE=76 at Ic=5.00mA
Vbe=0.610V at Ib=5.00mA
VceSat=0.019V at Ic=5.0mA and Ib=1.00mA
IcLeak=0.000mA
View attachment 1073686

View attachment 1073687

View attachment 1073689

View attachment 1073690

View attachment 1073691

Sansui NMA1718:
PNP Silicon BJT
Red-E Green-C Blue-B
hFE=63 at Ic=4.99mA
Vbe=0.583V at Ib=5.00mA
VceSat=0.060V at Ic=5.0mA and Ib=1.00mA
IcLeak=0.000mA

View attachment 1073695

View attachment 1073697

View attachment 1073698

View attachment 1073699

View attachment 1073700

FREAKING FINALLY!
The mysteries of the NMA output transistors are being plumbed. There was 0 data on those transistors online until now.

Good work Santhosh!
 
Ok! At home today doing Xmas clean up but I thought to take a quick peek at that toasted PCB I took out of my dead X11.

The mystery becomes a bit more mystery-er.

Looky here...
7B7B3D7C-97EB-4992-9718-F562F1880675.jpeg

No no factory cutting of traces necessary on my F-3460.

My PCB was designed with those traces already separated. No cutting of traces needed on mine.

So Santhosh’s and other X11’s with that cut are actually the first version of the X11.

So just to make it clear...

Cut
71F8BB12-FB79-46BE-A6BB-D20E35984F75.jpeg

Later...cut not needed.
7B7B3D7C-97EB-4992-9718-F562F1880675.jpeg

Surprise! Surprise!

BUT CONFUSINGLY...
From Amp8. A pic of an F-3460 with cut traces.
6A5C6CE5-83E9-4D32-8BBA-60BA68E9CCBA.jpeg

...but it has “Black Flags”
924BFC50-D071-40C0-88CA-867261F89B42.jpeg

Here is one that did not need cutting.
90C62167-662F-4E4B-8B0C-C22BE8E09640.jpeg

YET No “Black Flags” are used.
F140B935-2C53-4F10-A01A-B83C10E768F6.jpeg

WHAT THE HECK?
 
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This is visible on my AU-X11 driver board pics posted here. Excellent continued work on the documentation - keep it up!
To be frank, your driver board pictures, and annotations mentioned in your restoration post,and the work done by the rest were my inspiration to get things documented properly.
I am grateful to the work you have contributed to the forum, it was a start for me.

I am no technical geek or expert, but just learn from reading,and previous experiences and issues tackled by fellow members.
 
The mysteries of the NMA output transistors are being plumbed. There was 0 data on those transistors online until now.

To be frank, i still don't feel, these measurements are good enough to match output transistors.
The graph or plot from Peak Atlas is better than nothing we have had till now, but we still have a long way to go.

Below are the findings i managed to work out during my free time.
1. The current used for these measurements is 0.5ma.

Let's compare the data from Peak Atlas of Sansui NMC1718 and MJ21194(datasheet specs), and their Vce(X-Axis),Ic(Y-Axis) plots .

MJ21194(NPN) Collector Emitter Voltage Vs Collector Current
MJ21194(Vce Ice).jpg

Sansui NMC1718 Collector Emitter Voltage Vs Collector Current
upload_2017-12-25_20-0-21.png

Considering the differences between both the graphs, the spot on difference is the current used for calculation.
The datasheet graphs,the first line ( Ib = 0.5A ), has an Ic Value of 16 Amperes, approximately.
Whereas the plots for Sansui transistors are too low compared to the datasheet specifications, they have Ib values ranging in micro amperes, and max Ic value of 10mA used for testing.
10mA equates to 0.01A and it is no where near to datasheet specifications.

I am quite unsure, if the data from Peak Atlas is sufficient to identify a matching transistor, or least get some data out of it that can be compared with datasheet specifications.

Hfe values in datasheets are rated at a collector currents of 8A and 16A, whereas the peak atlas give you an Hfe value at 5ma.
Unless the Hfe remains the same at various values of collector current Ic, these values from Peak Atlas cannot be used for substitution.
Real time scenario, this is not possible, as you understand hfe changes with varying current.

Hfe.jpg

Note: These are my assumptions/interpretations on what i have observed, and i suggest the rest to not go by what i say.
I can be wrong, unless a fellow senior confirms my understanding.
 
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I basically have a color deficient eye sight and cannot make out the difference between various colour bands used in the resistor, i will have to seek help from my wife for the same.
I would have to identify tolerance levels for all resistors in the board that needs replacement.

Some high watt resistors are not mounted flat on to the PCB, and are mounted about 1 CM higher from the PCB, is this used to ensure good heat dissipation, as sticking them flat to the PCB hampers with heat dissipation, or is there some thing i am missing.
Resistor.jpg

I have measured couple of resistors on the driver board, and found them to be out of spec, will consider replacing those that are out of spec alone.
Since there is also an amplitude difference between left and right channels, i am considering replacing the resistors that are out of spec atleast.

Resistor Question:
1. Non Inflammable Resistor -> Replaced with metal film resistors
2. Cement Resistors- > Replaced with wire wound resistors

And are all the other regular resistors of Carbon Film type ?
Resistors Carbon Film.jpg

I rushed over to my local store to see if they some resistors available, yes they do but it is from a locally manufactured company called "Mercy".

Will rather prefer sourcing these from Mouser directly.

If some one can confirm if the replacements, and the carbon films identified are correct, i will proceed in sourcing the parts.
Also i read about fuse resistors, in AK, there none in the AU-X1 or the AU-X11 right ?

Regarding the Cylindrical Polystyrene capacitors, i am yet to make a choice and decide whether they need to be replaced or not.
I have to work on the values used (see if any of them are undervalued).
 
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To be frank, i still don't feel, these measurements are good enough to match output transistors.
The graph or plot from Peak Atlas is better than nothing we have had till now, but we still have a long way to go.

Below are the findings i managed to work out during my free time.
1. The current used for these measurements is 0.5ma.

Let's compare the data from Peak Atlas of Sansui NMC1718 and MJ21194(datasheet specs), and their Vce(X-Axis),Ic(Y-Axis) plots .

MJ21194(NPN) Collector Emitter Voltage Vs Collector Current
View attachment 1074180

Sansui NMC1718 Collector Emitter Voltage Vs Collector Current
View attachment 1074181

Considering the differences between both the graphs, the spot on difference is the current used for calculation.
The datasheet graphs,the first line ( Ib = 0.5A ), has an Ic Value of 16 Amperes, approximately.
Whereas the plots for Sansui transistors are too low compared to the datasheet specifications, they have Ib values ranging in micro amperes, and max Ic value of 10mA used for testing.
10mA equates to 0.01A and it is no where near to datasheet specifications.

I am quite unsure, if the data from Peak Atlas is sufficient to identify a matching transistor, or least get some data out of it that can be compared with datasheet specifications.

Hfe values in datasheets are rated at a collector currents of 8A and 16A, whereas the peak atlas give you an Hfe value at 5ma.
Unless the Hfe remains the same at various values of collector current Ic, these values from Peak Atlas cannot be used for substitution.
Real time scenario, this is not possible, as you understand hfe changes with varying current.

View attachment 1074182

Note: These are my assumptions/interpretations on what i have observed, and i suggest the rest to not go by what i say.
I can be wrong, unless a fellow senior confirms my understanding.

Nothing versus something. The something is gold.
 
Nothing versus something. The something is gold.
Another finding, on the older version of the boards used in the AU-X11, there are two non-inflammable resistors introduced after the tape cut in PCB, these resistors are also un-marked in the older version of the driver boards, as shown in below picture.
unmarked.jpg

The later version of the boards, have these marked R62 and R63, probably your driver board has these resistors numbered.

I further inspected the driver board and could see some stuff leaking out of the polystyrene capacitor.
Can anyone confirm if it is fine , or damaged and needs replacement.
polystyrene.jpg
It looks like something inside has leaked out of it, but the film looks good though.
 
There are three different types of resistors used in the driver board.
1. Non Inflammable Resistor -> these are replaced by metal film resistors right ? Correct me if i am wrong.
2. Metal Film Resistor->Replaced by metal film resistors that are available
3. Cement Resistor -> Replaced by wire-wound resistors

#1 is correct however be careful with #3 - as Cement Resistors can sometimes be low inductance types, (i.e. emitter resistors), which is very a important consideration, and thus should be replaced like-for-like. BUT you can of course use non-cement low inductance types - as I have done in the past using 'Mills' type resistors.

#4. Carbon film -> Replaced with metal film resistors. ;)
 
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I further inspected the driver board and could see some stuff leaking out of the polystyrene capacitor.
Can anyone confirm if it is fine , or damaged and needs replacement.

It looks like something inside has leaked out of it, but the film looks good though.

No, nothing leaking, that is a base for the capacitor, to maintain the radial lead spacing, and to protect the delicate leads and their entry to the capacitor body. (also indicates that they are good quality polystyrenes).
 
Regarding the Cylindrical Polystyrene capacitors, i am yet to make a choice and decide whether they need to be replaced or not.
I have to work on the values used (see if any of them are undervalued).
There is no better capacitor that you could use in those positions other than Polystyrene, everyone has used Silver Mica or C0G/NP0 Ceramic replacements due to the difficulty in finding low value Polystyrenes for these positions. If you find any damaged ones, I recommend you replace them with Ceramic. ;)
 
There is no better capacitor that you could use in those positions other than Polystyrene, everyone has used Silver Mica or C0G/NP0 Ceramic replacements due to the difficulty in finding low value Polystyrenes for these positions. If you find any damaged ones, I recommenrd you replace them with Ceramic.

Thanks for pointing it out, guiding me on the resistor replacements and also confirming that the polystyrene capacitor is ok .
Now I can put my mind to rest .

And yes I have the Murata C0G 100volt replacements with me and will use them if any polystyrene capacitors are damaged during the re-work.
 
Regarding Metal Film resistors - I have been using ones from Multicomp (available from Farnell & others).

Like these:-
http://uk.farnell.com/multicomp/mf50-10k/resistor-10k-0-5w-1/dp/9339787 = 0.5W
And these:-
http://uk.farnell.com/multicomp/mf25-10k/resistor-10k-0-25w-1/dp/9341110 = 0.25w

They are reasonably priced and I am very pleased with them.

Thanks John, and finally for carbon film resistors 0.33 watts, are these best replaced with a 0.25 watt metal film or a 0.5 watt metal film. Some resistor values are not available in 0.33 watts, and I am not sure whether to stick with 0.25 watts or 0.5 watts.
 
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