Swapping out for a US powersupply for a Sony MD Deck MDS-S500

[dibenga]

About to get my greedy hands on a Sony MD Deck MDS – S500 from Japan. It is NetMD capable and pretty robust for connections. Alas it has one hitch as since it is from Japan it uses 100v vs our western 110/120v power. From what I understand I will fry this thing if I plug it in direct.

I've purchased an external power adapter stepper which solves the issue but to me is clumsy and cumbersome. What I am looking to do is to replace or alter the internal power supply so it will safely run on US 120v/ Has anyone done this ?

Secondly, does anyone have the SM? I cannot find an English one .

Thanks in advance!

[sfbp]

My first reaction would be to say that the power adapter is an excellent device and works perfectly. I have one.

My second reaction would be to look at the schematic and see if you can figure out how to modify what's there, rather than putting in a whole new supply. Sony is very very careful about their components, and unless the one you got was from Sony, I would be rather sceptical of its ability to provide noise-free operation.

Sadly, this is the most recent deck from Sony (another reason not to mess with it), and I cannot find a service manual. I have a vague recollection from someone describing to me how Sony has (in the past) used strappings of the same power transformer (including a weird loopback backstrap which is the difference between 110 and 100 volts). But as this appears to be a domestic only model (correct me if I am wrong) I doubt if there are any such provisions.

I would NOT butcher this beautiful deck.

 

[NGY]

On 1/21/2021 at 8:51 PM, dibenga said:

What I am looking to do is to replace or alter the internal power supply so it will safely run on US 120v

While I fully agree with Stephen and would not butcher such a nice deck, I might have a non-destructive solution for you.

Without having the SM, first you would need to carefully lift the PSU board from the chassis, and take some good photos of both the component side and the soldering side. It would be also helpful to have the component side from a few different angles besides from above, as well as the solder side with a ruler held alongside next to the panel.

I need to check a few things then I can tell if my idea works or not. Again, what I have in mind is non-destructive and fully reversible, so no worries.

(To remove the PSU board you obviously  need to unplug the AC cord first, wait about a minute or two, then disconnect both the AC cord's and the main board's PSU cable connectors, and finally unscrew all screws that hold the board/main transformer.)

[bluecrab]

As far as I can tell, this JPN domestic-only deck doesn't have an SM in English. If you have a non-English PDF version of the SM, you could try one of the PDF language translators. Although I would not hesitate to take up NGY's generous offer, I'd give serious consideration to what sfbp said.

[kgallen]

I bow to NGY if he thinks the below is wrong or others in the local area that know the specs. 
 

I would compare the power network operators voltage specification for the US versus that of Japan. You may find that the US 110V +/- % spec versus the Japanese 100V +/- % spec overlap such that you can use the product as-is on the US supply without issue.

For example here in the UK our supply was nominally 240V ac, but in order to harmonise with the European supply of 230V ac, the spec of the UK supply was changed. No one changed any equipment either in the power distribution network or in their homes. This was a paper exercise only. The point being that equipment built for the European market is perfectly at home in the UK, or even Australia with its 240V supply.

This equipment generally uses a transformer. The result of the step-down means that the input being 110 or 100 will result in a much smaller change than 10V on the secondary.

Find the specs, do the maths.

Any other reason the two power supply scenarios differ that affects the conclusion?

Supply frequency is not an issue. US is 60Hz but the spec label on the unit shown above allows 50Hz and 60Hz. 

[kgallen]

Ok I did some research.

US is 120V +/-6% -> 112.8V to 127.2V

Japan is 100V +/-10% -> 90V to 110V

So US equipment needs to work down to 112.8V and Japanese up to 110V.

Internally, one logic supply rail is 5V. The unregulated supply for this would be 8V (minimum).  In the US this would require a 112/8=14:1 transformer. For Japan a 90/8=11:1

So if we stick US 127V into a Japanese 11:1 transformer we would get 11.5V out.

This 3.5V difference at the regulator input will result in slightly more power dissipation from the linear regulator. At the currents used by this equipment I would expect this to be easily accommodated in the thermal design. 
 

My MDS-E12 has a power select switch 100V or 220V. I think the intention here is it can be used on ~100V supplies (US/Japan) and ~220V (Europe/Asia/Australasia) supplies quite happily.

 

Comments?

[NGY]

1 hour ago, kgallen said:

Comments?

I like your approach, Kevin, and yes, on the low voltage DC side the regulator circuits should be OK with even a 15...20% higher input voltage.

However, the main risk here is at the transformer side. Not sure about Sony, but in the commercial goods world it is common to squeeze out the most possible performance using the least possible material.

When it comes to an AC power transformer, we speak about a lot of iron and copper to be saved. Then, when you consider how a transformer works, a 10...20% increase in the AC voltage can result a much higher increase in the energy "pumped" into the transformer, and that "extra" converts to different kind of losses (iron core loss, copper wire loss, etc.), and ultimately, heat.

Normally, such a transformer is designed to work near the limit of possible magnetic saturation of the core, to keep the size (= cost of the material) small. If you go over this limit, that's when problems happen. Same for the copper windings: the diameter of the wire is designed to bear the maximum current that particular device is expected to draw. But if you increase the voltage, with the same copper resistance, the current will increase, so will the heat generated inside the copper. On top of all, this is a non-linear function :-( . I.e., 10% more current (or voltage) means 20+ % more energy, and 20% more current means 40+ % more energy.

We did not speak about electric and magnetic (also, audible) noises of an over-saturated transformer, or voltage swings on the AC net, that can take the input AC voltage way higher, than the nominal value. Example: it is not uncommon on the 230V grids, that the voltage occassionally goes up to 238...242V. I believe it is similar on the 100/110/120V grids too. Imagine, if a device meant to be used on a 100V line gets a - say - 125...126V AC input voltage on a 120V net.

 

 

[sfbp]

Nope. Don't do it. That's how my CMT-PX3 (DHC595MD) got toasted before I ever received it. When I got the drive back from Jim, I found that same power->100V converter. Magically everything stopped overheating.

Our voltage here is closer to 120 than 110, routinely. Not sure about Nova Scotia.

[bluecrab]

You EE-types are paying good attention to every detail! I have a mundane observation to contribute. My Sony MDS-JA22ES was a Japan domestic model, 100v. My being in the US, to be safe I used a stepdown to get to 100. There were some well-documented (here) issues with the unit, but power wasn't one of them.  But the display, while good, was on the dimmer side, especially when compared to other MD decks near it. So I gave it a try minus the voltage converter. The display brightened up considerably. However, the majority of opinions that I sought advised that long-term, probably not the best thing to do. I retreated to converter safety and put up with the dimmer display. Compare this to my MXD-D400, also a Japan domestic, also using a converter—in fact, the same converter the 22ES  used. It has a normal, bright display and has never been subjected directly to US voltage. I suppose what I am saying is that for a machine like the S500 or my D400, perhaps it is better to just use a converter if that is reasonable. The S500 in particular is a rare find. Like to note that my converter, while not a brick, is larger and more substantial than a travel-size one I had, which eventually failed. If the D400 is happy, then I'm happy!

[kgallen]

Great insight guys! A converter it is! :-)

[NGY]

4 hours ago, bluecrab said:

My Sony MDS-JA22ES was a Japan domestic model, 100v. My being in the US, to be safe I used a stepdown to get to 100. There were some well-documented (here) issues with the unit, but power wasn't one of them.  But the display, while good, was on the dimmer side, especially when compared to other MD decks near it. So I gave it a try minus the voltage converter. The display brightened up considerably

Interesting - the display of my (EU version) JA20ES is also somewhat dimmer compared to my 640 next to it, although the 20ES was hardly used (~220 hrs only) when I bought it. Could that be, that in those top-end models Sony intentionally decreased the anode-voltages, to allow longer lifetime for their VFD-s?

[bluecrab]

14 hours ago, NGY said:

Interesting - the display of my (EU version) JA20ES is also somewhat dimmer compared to my 640 next to it, although the 20ES was hardly used (~220 hrs only) when I bought it. Could that be, that in those top-end models Sony intentionally decreased the anode-voltages, to allow longer lifetime for their VFD-s?

Anything is possible, I suppose. But...I owned two JA20ES (US models), both bought used, and neither had the dim display issue. Same for my 333ES (US).

[NGY]

On 1/21/2021 at 8:51 PM, dibenga said:

What I am looking to do is to replace or alter the internal power supply so it will safely run on US 120v

I admit we diverted your topic a bit - nevertheless, are you still interested in a possible solution?

[dibenga]

Actually I've enjoyed the discussion. I have the unit now AND a power diverter. I still have no decided what to do but this thread gives me enough to think about. The unit I received is pristine and now it feels wrong to open it up and 'butcher' it's insides. The power inverter that  I got is quite small and not as cumbersome as I originally expected. However if I do decide to pursue it I will be reaching out to those in this thread to get help. SERIOUSLY Thank you everyone!

[Richard]

18 hours ago, dibenga said:

Actually I've enjoyed the discussion. I have the unit now AND a power diverter. I still have no decided what to do but this thread gives me enough to think about. The unit I received is pristine and now it feels wrong to open it up and 'butcher' it's insides. The power inverter that  I got is quite small and not as cumbersome as I originally expected. However if I do decide to pursue it I will be reaching out to those in this thread to get help. SERIOUSLY Thank you everyone!

Enjoy the unit. If the transformer is the Kashimura in the original picture then it is indeed tiny. I have a lot of Kashimura transformers and they are very reliable. Even the 100w to 200w capacity ones are not much bigger.