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Mz-rh10 Bad Connection Or Design Flaw?

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Hi everyone,

Thanks for the help I get from reading your previous topics... it has been invaluable.

I have a problem with the MZ-RH10 that I had delivered yesterday.

It is very good but there are a few issues, like the character input matrix only partly appearing (as mentioned in a previous post), the SonicStagev3 software being very slow for me (maybe it's my old computer too)...

BUT my main issue is this;

When I have the unit connected to external power by either the AC adaptor or the USB bus it is clear that the unit is not properly earthed. I mean the metal casing that runs around the sides. When I touch it it buzzes (like touching a guitar cable or whatever...y'know), and gives me little static shocks. I don't think the problem is there when running on batteries only, but if it was it might be draining the batteries unnecessarily.

Now, I know it's not gonna kill me as it is only 3 volts, BUT should I send it back to the shop?!! Does anyone else have the same earthing problem? Is it worth sending it all the way back to A/\/\az0n? Or is it a design flaw in all the units?

Thanks in advance guys/girls,


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I'd definitely think that is a problem. The unit should definitely NOT give you ANY sort of shock or buzz, no matter how minor.

I'd suspect you're right, something internally in the unit is not grounding. I think if this were a design flaw, more people would have noticed it already, so I suspect yours is just a defective unit.

(I don't have one, but I have a 910 on the way... I'll check it out when I get it to make sure it is not exhibiting similar behavior)

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definitely your unit is defective. go to: eservice.sony.com (without the www). there you can ask for a repair or an exchange from sony (if you're in u.s).

about that "missing caracthers" problem check this:


sony will do a firmware update to fix this problem. so, if you ask for a repair don't forget to mention that you want the firmware update.

hope that helps


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i have the same problem here. might be that the supplied adapter is a two pin USA adapter.. while i stay in india and use a step down as my power supply is 220V.. here, we use the 3rd pin for earthing.. it could be that the 2 pin adpater made for the usa where earthing might already be there( please correct me) is not earthed in india..

i have a friend leaving for the us in a week.. please let me know if i need to send it back with him for replacement or service... thanks

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The problem is the included power supply.

It looks like to reduce interference, they connected from secondary ground a small capacitor to each of the power lines.

Normally these capacitors have an X2 rating.

That means, maximum voltage is 4kV, so from that point,

it is save to use it.

The PSU included with my NH700 has the same effect.


Solution: Plug in the audiocables first, then plug in the PSU.

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Firstly, thanks for all your replies.

veezhun and jadeclaw: The problem is not the supplied AC power supply because it is still present when the USB bus power is used instead. sad.gif

So I'm sending it back to Amazon. Luckily their returns department seems quite well organised. I will let you know what happens. Anyway, it gave me a chance to re-think not buying an iPod or other HD-unit instead... I'm happy with the RH10, even with the apparent niggling problems it has.



Edit: Oh, and I forgot to mention that I am in the UK!

Edited by Tea&Crumpets
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OK so I got a 2nd unit delivered and it has the same problem. Thus I have come to the following conclusion(s):

1) The RH10 is earthed to its own casing. This is how it is designed, but to avoid problems with external power you MUST have a power supply with an earth pin.

If you do not then recording with a microphone (well, the one I have anyway) while plugged in to ac power gives a lot of hum, rendering it useless (because the power running thru the casing seems to also connect to the mic input).

Also, if you are playing through a Hi-Fi using the headphone socket as a line out then touching metal parts of the casing produces very loud and noticeable hum, which could be very annoying in particular situations.

2) Sony have overlooked this AT LEAST in the UK, where they have distributed the units with power supplies that have a plastic earth pin, i.e. no earthing. I tried the unit with the power supply from my old MD player (the Sony MZ-R55 cool.gif ), which has an earth pin, and this solved ALL the problems.

3) The same problems occur when the USB cable is connected up, and the unit is running from the USB bus power, BUT this doesn't matter so much because you cannot record with a mic now anyway, and there is no need to listen through line out or whatever, you know what I'm saying.... smile.gif

4) When USB or AC external power are connected to the RH10 unit, touching the metal casing can result in small electric shocks! (But don't worry because it is only 3V, 1A. So it won't kill you. However it is noticeable). My friend verified this. If you don't believe me, rub the hairs of your fore-arm across the top-left corner of the metal side-casing!

So, perhaps someone else in the UK can verify this for me. Like I said, I have tested this on two separate RH10 units/power supplies.

And people elsewhere in the world, try what I said with the USB cable attached... it should do the same thing as mine! Please try it and see. Connect USB with the line out attached and touch the casing (obviously the volume on your hi-fi needs to be moderate).

So to clarify, the problem is not that anything is broken. The problem is that, because the RH10 casing is connected to earth, it NEEDS an AC power adapter with an earth pin, which Sony have not supplied in the UK. mad.gif Surely they could have tested these things together first!!!

BTW, Amaz0n sent me a new one straight away, and I sent them back the first one yesterday in the post. They said they will refund the cost of that.

Hope this helps someone!


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You have the buzzing problem with USB?

Well, sending back the first one was useless.

And the case must be connected to the recorders ground to prevent interference from radio transmitters and to prevent the pickup of noise and hum.

Since you have it with USB as well, that simply means,

1. That you are using an laptop computer with a power supply, that is wired like the recorders wall wart - 2 pole mains plug and two capacitors to secondary minus.


2. You are using a desktop machine with a 3 prong plug and either the grounding system in your home is on the fritz or the mains wall socket has a broken contact or a broken wire inside its crater in the wall.

It could also be an extension cord or multiplug you are using, so check that as well.

In that case, the fault should be corrected immediately.

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Sorry but I don't think that either your first or second suggestion are correct.

If it was a problem with my laptop then it would only occur when USB was used. However I will play around a bit more when I get home today.

Thanks for your suggestions.

EDIT 12/6/05: Sorry I am using a laptop and I have been using it on plug in power recently! My mistake! So maybe this is the problem with the USB... no earth pin!

Edited by Tea&Crumpets
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The bit about getting shocks certainly isn't normal, but the bit about hum when using a plug-in powered mic at the same time as AC power -is- normal. All MDs I've tried this with [using stock AC adapters] have done this. The solution to that particular problem is usually to buy or make a regulated, filtered power adapter, as it appears that Sony are too cheap to include $0.02 capacitors or $0.05 voltage regulators in theirs.

[Yes, I've also tried the same with regulated power, and as with battery power, there is no hum. Incidentally, their video cameras with plug-in power mic jacks also have the same problem, depending on what kind of power supply they come with.]

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