What the heck is this thing?

Discussion in 'Computer Hardware, Devices and Accessories' started by Lucifer666, Mar 20, 2015.

  1. Lucifer666
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    Lucifer666 all the world needs is me

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    Long story short I sort of forgot that some American electronics are capped at 120 volts and I plugged an American record player into one of the sockets in my house (around 230V) and it wouldn't switch on and I could smell something burning.

    I immediately disconnected it and waited about 20 minutes before trying to turn it on with a step-down converter this time (and I know it works, because I use my american imported Wii U on it and everything) but it still wouldn't work.

    So I did the next logical thing which is to open it up and find the source of the problem. I assumed that, if it were designed smartly, then it's just the fuse that I've burnt out. After taking the record player apart I found the source of the smell, and it doesn't look like a fuse? I mean I have no idea, take a look for yourself:

    Warning: Spoilers inside!

    All right so as the title says, what the heck is this thing? Is it a common item I can find at a hardware store or is it specific to this model of record player? Thanks
     
  2. kristianity77

    kristianity77 GBATemp old fogey

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    I think thats your power transformer.
     
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  3. DCG

    DCG GBAtemp Advanced Fan

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    That's a transformer.
    120V goes in on one set of wires and comes out at 12V (?) at the other. (I guess)

    The caps haven't blown on the PCB, so my guess is you could save it with a new transformer (perhaps even a 230 to xx (needed ammount)? ).
    I'm not a electrician though, so I don't know if there is 120V being used somewhere else in the player, or if there are more components between the transformer and the power cable.
     
  4. sandytf

    sandytf GBAtemp Regular

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    That is a transformer and they are generally not easy to replace as they are often custom made. What is the part number listed on the top? Just be very careful when it comes to modifying or repairing power supplies. Especially if you don't know what you are doing, they can be extremely dangerous.
     
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  5. The Real Jdbye

    The Real Jdbye Always Remember 30/07/08

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    This is just a guess, but it looks like it could be an electromagnetic coil with plastic coating on the outside.

    Edit: :ninja: and my idea didn't make that much sense anyway :P
    Well if it's just a transformer, you just have to find out the output voltage and find a power brick that matches. and you can bypass that part of the circuitry completely. Plus then you can get one that works for 230V too.
     
  6. DCG

    DCG GBAtemp Advanced Fan

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    http://www.honkwang.com/p3-6.htm
    Top picture second from the left at the bottom line.
    That looks to be the same thing.

    Don't know the site other than by googling "E84506".
    I'd say you could at least find the specs of the current one on there and ask a friend who's got electrical skills if he can look into it.
    (if you wire it wrongly it'll break again and/or set your house on fire)
     
  7. dandreye

    dandreye Newbie

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    Lucifer666:

    Hi, may I ask if you got it fixed eventually and if so which particular transformer you got installed instead of the burnt one? Trying to find a suitable 230V replacement one for my Denon DP-29F purchased in the US.

    Thanks in advance!
     
  8. FAST6191

    FAST6191 Techromancer

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    I found a service manual for the device on the following link, also attached it here
    http://www.pickupnaalden.com/images/pdf/Denon-DP29F-service-manual-engels.PDF
    Page 11 has the schematics, and it appears it is different between the EU and US/Canada models.
    Internally it is referred to as part 46 and has a part number of
    941 0005 104 Transformer for E3
    941 0005 201 Transformer for E2
    E3 : U.S.A.&Canada model
    E2 : Europe model

    0005 104 is the one you have as standard. It is a pretty meaningless number and a basic search did not get me anything more on it (sometimes replacement dealers will put the specs on it but not in this case).

    Alas without the rating of it I can't say pick this. However it looks like a basic single tap transformer that gets full wave rectified before it does anything so it should not be anything too hard to sort otherwise should it come down to it.

    If the transformer itself does not say what it does then what does the motor say its voltage is? Hopefully it is not a range.
    The TA7325 chip has a maximum input voltage of 18V http://www.alldatasheet.com/datasheet-pdf/pdf/101816/TOSHIBA/TA7325P.html
    The C1 capacitor appears to be rated at 16V but I have seen devices made by big manufacturers over volt their capacitors so I do not want to read too much into that.

    If the transformer has not burned out then you can figure it out, though do be careful and find someone that knows what they are doing if you do not -- if you take it off, put 240V in on the yellow wires of that and the brown ones could well end up at well over 1000V (practically it will be a bit lower but more than enough to ruin your day).

    In general I should also say that Europe does 50Hz which can be troubling for 60Hz devices as 50Hz actually means more power is transmitted (look up a term called duty cycle), and if nothing else some things, especially legacy audio equipment, can use the mains voltage as a timer so you might find everything variously sped up or slowed down by a noticeable amount. Again though here everything seems to be fully rectified so that should be fine.

    If you know someone that knows electronics this should be a simple project to adapt, do take the manual above with you when you do go though.
     

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  9. dandreye

    dandreye Newbie

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    FAST6191:

    Thanks for your detailed reply. So I must have 941 0005 104 now and need 941 0005 201 instead of it. The latter one seems to be superseded by 941 0005 214 available in particular here:
    http://www.ebay.co.uk/itm/291489758763

    Further search has let me to their maker, Hon-Kwang Electric Co (their logo - HK in a triangle - can be seen at the top of both 941 0005 104 in the pictures in the initial message of this thread and 941 0005 201/941 0005 214). From schematics I understand its output is 12VAC as the Moretech motor connected via rectifier circuitry has 12.0V on the label on its body (DC this time of course):
    [​IMG]

    I guess I can easily measure current transformer's output using voltmeter w/o any risk as I happen to have a 220VAC-120VAC converter too. I haven't found such HK transformers elsewhere but can see plenty of unbranded 220VAC/12VAC ones. The only thing that worries me wrt transformers is that the doc has "!" in a triangle right next to it (and the power plug) and that sign means "only use exact same Denon part". How likely is it that an unbranded 220VAC-12VAC equivalent of 941 0005 201/941 0005 214 with the same output VA rating (3VA according to my research) will cause any adverse effects?

    On frequency: I have 2 conflicting responses from Denon: one - from their US rep saying literally this: "Turntables need the correct AC cycle, either 50 or 60 Hz to operate properly. The US model will not work at 50 Hz. There is no modification available by Denon to change this." and one more - from their Germany rep saying literally this: "you need the both part : 9410004804 (AC CORD DP29F) and 9410005201 (POWER TRANS DP29F)". Unless I'm missing something my device has been as happy as ever with 50Hz over almost 12 years of occasional use by now (afaik voltage converter is reportedly unable to convert frequency), so their former response looks somewhat questionable if taken literally. Perhaps they wrote that with some ideal rpm figure in mind?.. Meanwhile the doc lists several country specific parts (5, 6, 7, 10, 44, 46, 50, 151, 152) and I'm really wondering why: could that "select record knob", "square knob", "tone arm assy" all be critically sensitive to the frequency and if so why are they all still alive in my DP-29F?... Btw the same applies to model DP-300F as follows from its respective service manual.
     
    Last edited by dandreye, Feb 21, 2017
  10. FAST6191

    FAST6191 Techromancer

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    12V would be in line with many things, should power the amp and is a common voltage to boot. If you have a 120V transformer and the player still works then measure away, far nicer than counting turns or any of the other methods.

    Some motors change in speed depending upon the frequency you put in. In some legacy gear it will mean the motor spinning the record/reel/whatever runs accordingly faster or slower (and a really noticeable 12% or so for 50Hz to 60) and that will have a knock on effect to the resulting music (I don't know if you watch techmoan on youtube but the magnetic wire audio player he had the other month was a good example of this). If you are really bothered you can make arbitrary frequencies, the main device to do it is called a VFD (variable frequency drive) and machinists use them all the time rather than changing gears on their tools. However they are not ideal for some audio gear. There are even older things (various generators and rotary phase converters) but don't go there if you can avoid it.

    From the specs I saw the thing is rectified and smoothed before it does anything in it. The only way I can see it troubling things here is if the circuit was not smoothed enough by the capacitor and the ripple was the timer but that is really quite silly, or if again it is not smoothed fully and something about duty cycle and heat dissipation.
    You don't need the same VA/power rating, don't go lower unless you are sure but you can go higher if you want and that is all the shop has/has for a decent price*. Whether you can wedge it into the case is a different matter and I think one of the smoothing capacitors was attached to it but that is neither here nor there, and while I have not pulled it apart going by the exploded diagram there should be a bit of wiggle room.
    If you really wanted you could probably chop out the transformer and rectifier (maybe leave the smoothing cap) and stick a wall wart/switch mode supply in there (12V and next to no Amps is easy to find). They can be a bit noisy, especially modern switch mode stuff, but try if you like.

    Had the transformer been some kind of crazy multi tap thing that generated 10 different voltages, parts of the thing used AC and so on and so on then yeah trying to find a generic replacement would be hard. This is an absolutely basic, first principles transformer doing a common voltage and not gobbling a lot of power by the sounds of things. If you want to use denon stuff, and it will likely bolt straight on, then go for it.

    * https://www.rapidonline.com/vigortronix-vtx-120-003-612-pcb-open-mains-transformer-3va-0-12v-88-3702 has one that will do (you will have to jump the middle pins as it is designed for 120 and 240V, like I imagine Denon would have done in the first place like every other manufacturer for the past 20 years) for a whole £2.85 plus VAT and shipping (or nothing if you live anywhere near Colchester and can get to their shop). I don't know what maplin will have and I would rather not spoil a good evening by fighting with their site. The cable is just a cable so use whatever you like, do make sure to earth it if there are external metal parts that could become live.

    I don't know why the case and parts are different between the runs, I could speculate, and that would also lead me to wonder why it was not a universal transformer and regulator setup, but were I a betting type I would go with no effect on resulting audio.

    As for why denon reps said don't do it then I am going with they either want to sell you something or they are covering their arses -- they might well have other models on the market with a drive that does need set frequencies and can't be bothered to look it up or risk telling you the wrong thing.
     
  11. dandreye

    dandreye Newbie

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    > Some motors change in speed depending upon the frequency you put in.

    I was actually under impression that it's always the consumer e.g. a motor that decides exactly how much amps of DC voltage it wants to pull, i.e. no way to push any more energy into it anyhow. Not challenging or questioning anything at all as I have almost 0% background in electrics, just thought 12VDC is same everywhere and power consumed = 12VDC multiplied by amp draw, hence same amount of energy. If I read schematics right no parts incl the motor use AC - only DC from rectifier egress, so the only part exposed to AC frequency is the rectifier itself, isn't it?

    I'm currently watching this one:
    http://www.ebay.co.uk/itm/291964204382

    It's a quid higher but includes delivery (I live near LHR airport and no longer travel near Colchester) and has the same dimensions and this bracket with ears, thereby looking like a perfect match both mechanically and electrically. "Yours" looks more professionally built though. Thanks for the link anyway.
     
    Last edited by dandreye, Feb 22, 2017
  12. FAST6191

    FAST6191 Techromancer

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    The following has a nice overview of motors if you wanted


    and yes it is the device (in series with everything else) that determines the current drawn, classically this is the V=IR equation. Modern power electronics can turn higher power things on and off fast enough though that you can change speeds in motors, and for those using multiple phases then it changes how fast the fields change and with it how fast the rotor follows/gets pulled around.

    For anything other than a record player I would have said more, however record player makers have a bit of fetish for odd motor approaches; if you have ever seen all the direct drive vs belt drive thing then this plays into that.

    But yes if the schematics are accurate the only thing on that which is subject to AC is the rectifier and thus nothing here is going to be bothered.

    Also I fought with maplin's website and apparently they do something
    http://www.maplin.co.uk/p/12v-250ma-miniature-transformer-yn16s
    They appear to want £8 for it and as it is maplin I imagine the quality is going to be worse than your ebay listing. I don't like that your ebay transformer is rated for 220V (China uses 220V but UK mains is usually closer to 240V, this means just over 13V will come out of it) but it should still perform as all that has no great voltage regulation in it and if they cared they would have done it*.

    *I say 240V but it is a mild suggestion in some places, and stateside it is worse so when people need precise voltages they do more than rectify and smooth.
     
  13. dandreye

    dandreye Newbie

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    Nice video: thank you )

    Sorry I omitted the fact that the turntable is actually with my parents outside UK now and I doubt they have any more than 220V, so using a 240V transformer (rather than a 220V one) may even be suboptimal. Once I'm there next I'll measure the voltage and duty cycle at the current transformer's egress to be sure. Will be back to report my experience when all done (will take a while though).
     
    Last edited by dandreye, Feb 23, 2017
  14. dandreye

    dandreye Newbie

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    The transformer has been replaced: I ended up buying at £3.87 the 12V 200-300mA one I was watching (according to my research it's Uxcell a13042200ux0289), which appears to have gone up in price since then. It fitted perfectly well mechanically and I just had to put its 220V wires into heat shrink tubing as their native insulation is as thin as its 12V one is. Sadly I didn't have time to connect audio output to the amp and test the sound on this occasion but it clearly spins no worse than before at a glance, so it should be fine. I'll do my best to test it in July when I'm there again.

    If anyone (perhaps topic starter although over 2yrs have gone by) wants barely used original US transformer I can ship it to you just for the cost of shipping (my email is dandreye@gmail.com and I'm in UK):

    [​IMG]
     
    Last edited by dandreye, May 10, 2017