AU-X1

[Hyperion]

That said...would replacing the lower voltage electrolytic caps with polypropylene film caps be OK?

I don't think you would find polypropylene replacements for electrolytics of a reasonable size and working voltage, polyester however is entirely possible.

So if the old cap was 10v and a step up is fine and even preferable to say 16v is 25v or even 50v to high?

Oilmaster is correct in my humble opinion, and yes I believe a 50V replacement for a 10V original would be too high.

There has been a few cases where I could not find one in the right voltage and stepped it up quite a bit.

Electrolytic capacitors should ideally be used at around 80% of their working voltage, however, it seems you can get away with bigger deviations as the capacitors themselves are so much improved.

 

[Willy6]

I don't think you would find polypropylene replacements for electrolytics of a reasonable size and working voltage, polyester however is entirely possible.


Oilmaster is correct in my humble opinion, and yes I believe a 50V replacement for a 10V original would be too high.


Electrolytic capacitors should ideally be used at around 80% of their working voltage, however, it seems you can get away with bigger deviations as the capacitors themselves are so much improved.

John did you remove the old solder and resolder everything?

 

[Hyperion]

John did you remove the old solder and resolder everything?

No, as is my standard procedure I only use new solder for components I am replacing. I normally replace the solder when I rerun the few poor joints that I do find, and I use a watchmakers eyeglass to find them.

I believe it is poor practice to rerun/reflow all the solder joints, but I do usually make a 100% visual inspection of all joints, especially if the existing soldering looks suspect without magnification.

 

[Leestereo]

...a step up in voltage with a new cap was fine and even preferable. Going too high would however mess up the quality of a circuit as capacitors require "a certain tension" to function properly / efficiently.

+1
With electrolytic capacitors, the applied voltage has to be high enough to form and maintain the insulating oxide on the plates.

That said...would replacing the lower voltage electrolytic caps with polypropylene film caps be OK?

Generally, film capacitors can be used to replace their electrolytic counterparts as long as the the voltage rating is at least as high as the original electrolytic capacitor rating (or whatever voltage the capacitor is subject to in the circuit). Note that there is no issue with a minimum voltage needed to form an insulating oxide with film capacitors, e.g., a 100V film capacitor can replace a 6.3V electrolytic capacitor.

 

[Leestereo]

...I believe it is poor practice to rerun/reflow all the solder joints, but I do usually make a 100% visual inspection of all joints, especially if the existing soldering looks suspect without magnification.

+1
There is no advantage to heat-stressing a component if you don't have to...there is a local flipper of vintage electronics that advertises that he re-solders every single component, but typically will not replace any component since he "doesn't want to change the sound"; this is NOT an approach that I condone...

However, it may be worthwhile to add solder to components that are subject to heat cycling (e.g., power resistors, regulators) since the amount of solder present on these components is relatively minimal with automated wave soldering.

 

[Willy6]

John I noticed on some of your work you use ceramic beads or something on exposed leads (like the resistor in this pic)my question is have you ever used shrink tubing?I have lots of that but don't have any ceramic beads.

 

[Ronito6]

Ceramic spacers / insulators / shielding is what I think you mean. (I think.)

One above the brown diode with the SV label for example. The newer looking small blue resistors.

PIC from Hyperions thread http://audiokarma.org/forums/index.php?threads/restoring-an-au-x1.709469/page-2

 

[Willy6]

Ceramic spacers / insulators / shielding is what I think you mean. (I think.)

Yes shielding

 

[Ronito6]

Yeah...I intend to get a pile of those for my next project too.

 

[Willy6]

Ceramic spacers / insulators / shielding is what I think you mean. (I think.)

One above the brown diode with the SV label for example. The newer looking small blue resistors.

PIC from Hyperions thread http://audiokarma.org/forums/index.php?threads/restoring-an-au-x1.709469/page-2

Yep the same board I'm working on now..

 

[Willy6]

Yeah...I intend to get a pile of those for my next project too.

Anything wrong with heat shrink tubing?

 

[Willy6]

Yeah...I intend to get a pile of those for my next project too.

Are there any problem transistors on the x-1 I should know about? So far all of the ones I've checked are still good.

 

[Ronito6]

Anything wrong with heat shrink tubing?

If you mean as a stand-off spacer like Hyperion shows...pass on that idea.
For that use, heat shrink tubing can in no way stand in for ceramic. It would be extra work for zero benefit. Easier to just mount the resistors slightly off the board.

The true goals for mounting resistors slightly off board are ...

1. to allow better air circulation around the component to keep it cooler and thus more reliable and stable
   
2. to greatly reduce heat transfer between components through the PC board.

That really takes very little space between the component and the board.

The benefit of mounting the resistors as high as Hyperion has is not only good air circulation around the component, but to keep the resistors from burning the PC board should it for any reason overheat.

Are there any problem transistors on the x-1 I should know about? So far all of the ones I've checked are still good.

I would say that the FETs are the most likely transistor components to need replacing. They are difficult to replace due to rarity. And finding and installing substitutions are high-alchemy and also suffers from supply issues.

That said...don't worry about them yet. Do the work you are able and just assume all is ok on the FET front.

Only the highest experienced techs like Kale or Amp8 can sort out an X1 in one try.

Noobies like you and me...after you have finished and have it all back together...prepare for the possibility of up to 3 more major "operations" on your X1 before you call it really finished.

 

[Ronito6]

Oh yes....and be careful of overheating your polystyrene caps since they can be easily damaged. Use a heat sink / heat shunt on the leads if you must re-solder them.

Heat can travel up traces which the polystyrene caps share with other more rugged components. In this case, heat can travel from the installation of a trace sharing component, through the trace, into a polystyrene cap... thus damaging it

Polystyrene is just another word for Styrofoam.

And I am rather certain you know the effect of heat on Styrofoam.

It is probably best just to leave those alone.

 

[Hyperion]

If you mean as a stand-off spacer like Hyperion shows...pass on that idea.
For that use, heat shrink tubing can in no way stand in for ceramic. It would be extra work for zero benefit. Easier to just mount the resistors slightly off the board.

The true goals for mounting resistors slightly off board are ...

1. to allow better air circulation around the component to keep it cooler and thus more reliable and stable
2. to greatly reduce heat transfer between components through the PC board.

That really takes very little space between the component and the board.

The benefit of mounting the resistors as high as Hyperion has is not only good air circulation around the component, but to keep the resistors from burning the PC board should it for any reason overheat.



I would say that the FETs are the most likely transistor components to need replacing. They are difficult to replace due to rarity. And finding and installing substitutions are high-alchemy and also suffers from supply issues.

That said...don't worry about them yet. Do the work you are able and just assume all is ok on the FET front.

Only the highest experienced techs like Kale or Amp8 can sort out an X1 in one try.

Noobies like you and me...after you have finished and have it all back together...prepare for the possibility of up to 3 more major "operations" on your X1 before you call it really finished.

Spot on Ron

(also used for zener diodes as they are inclined to get warm, and the cooler they are as voltage references the happier they will be, as will the amp, and you )

 

[Willy6]

Spot on Ron

(also used for zener diodes as they are inclined to get warm, and the cooler they are as voltage references the happier they will be, as will the amp, and you )

When I ordered my capacitor's if I couldn't find a certain value in the nichicon fg series I would look at what Panasonic had and on boards f-2771-70 there are some 330uf 50v caps and the closest ones in the fg series are 63v so I ordered some of those and some panasonic EEU-EB1H331 which are 50v.Should I use the Panasonic's or the 63v FG's?

 

[Hyperion]

Use the Panasonics - they are 105C rated, those phono amplifiers get hot, the FG's are 85C rated. And the Panasonics are almost certainly lower ESR/higher ripple current than the FG's - which is just what you want as they are for power rail decoupling - C17 and C18.

 

[Ronito6]

Spot on Ron

(also used for zener diodes as they are inclined to get warm, and the cooler they are as voltage references the happier they will be, as will the amp, and you )

Thanks John! And you're right...

Mind your diodes Willy6. There are the M12 / VD1212 pro forma replacements to consider. The zener diodes to check and possibly replace. And that one germanium diode on the drivers to check and possibly replace.

X1 restoration is a lot of work.

 

[Willy6]

Thanks John!

And you're right...Mind your diodes Willy6. There are the M12 / VD1212 pro forma replacements to consider. The zener diodes to check and possibly replace. And that one germanium diode on the drivers to check and possibly replace.

X1s restoration are a lot of work.

I new this was gonna be a huge job and a great learning opportunity for me .

 

[Ronito6]

Use the Panasonics - they are 105C rated, those phono amplifiers get hot, the FG's are 85C rated. And the Panasonics are almost certainly lower ESR/higher ripple current than the FG's - which is just what you want as they are for power rail decoupling - C17 and C18.

Yes the X1 is quite a toaster.

The X1s phono stage when finished is covered by big metal cowling. This is the same on the X11.

On the X11 Sansui applied thermal paste on the tops of the heat sinks of the PCB cards that populate the phono motherboard. So, when the cowling is in place, heat transfers from the cards into the cowling.

So the X11 incorporates the cowling into a heat dissipation role rather than just being a covering as it is in the X1.

I recommend doing this to the X1's phono stage cowling too.
Add thermal paste to the tops of those card's heat sinks, and make that phono stage cover part of the heat dissipation scheme.