Sony AC-122 power adapter. Dead?

Discussion in 'Tech talk' started by Chris_D, Apr 4, 2024.

  1. Chris_D

    Chris_D Active Member

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    So on my daily trawl around the good old Marktplaats.nl (NL's premier website for all stole... I mean, second-hand wares) I came accross a 'Vintage Sony adapter' for sale. Low asking price and the seller accepted an even lower offer from me. So I thought I'd risk it for a biscuit.

    Arrived yesterday in what actually looks like the original box, although it has no labels but it has cardboard inserts which seem shaped to the shape of the housing and inserts for the cables. Nice.
    I've been open to finding a cheap one to power the D5M for a while now as it's a bit irritating when the admitteddly fantastic 10000maH Amplemann batteries eventually run out and need charging. As it mostly sits on the end of my workbench an adapter would be the logical choice and save charge-cycle wear on the batteries

    Came with a US plug attached but no biggie, I just plugged it into my travel plug and set it to 220v input and hooked up the MM. Set output at 4.5v and I get .5v. hmm. Set to 6v and I get...0.5v. hmm.
    Can anyone verify if it needs to sense a current draw in order to ramp up to the correct output voltage? It seems optimistic that something of this vintage would do that, but you never know?

    I read @Deb64's excellent thread advising NOT to use an adapter with a D6c and I think that's VERY sage advice! Does the same apply to the D5M?
    (for anyone cross-referencing this thread:
    https://stereo2go.com/forums/thread...-this-before-plugging-in-any-dc-adaptor.7840/

    I'm sure I was using an adpater when I first got this D5M about 5/6 years ago. Maybe I actually have another adapter around here that I totally forgot about. Maybe I sold it with a walkman or something. oops.

    Any ideas if it should actually be outputting a constant indicated voltage?
    I had a poke around inside and everything looks ok; fuse, 4700µF Elna cap, no burning smell or indication of burnt-out components, all wiring has continuity.
    Is it brown bread (dead)?
    or attempt a repair?

    IMG_20240404_173738_1.jpg IMG_20240404_175745_1.jpg IMG_20240404_175955_1.jpg IMG_20240404_174738_1.jpg IMG_20240404_175332_1.jpg
     
  2. Chris_D

    Chris_D Active Member

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    Arrrrrg!
    Well, a quick shufty around some cupboards revealed a box with not only the 6v adapter i was using with the D5M way back when, but also an original 3v centre-negative adapter and the hankiest, jankiest looking hanky-janky piece of turd adapter that I actually remember receiving along with a D6C. The owner must have been using it at some point as he's labelled it 'Sony WM.D6C' lol.
    I think it's going straight in the bin!

    I think I'm becoming a proper forgetful old git in my old age lol. Ireally ought to have a good clear-out at some point. Who knows, I may even find some cash money stashed away somewhere...or some priceless first editions... lol !
    :loldiag:

    The long-lost booty
    IMG_20240404_190307(1)_1.jpg

    nice, steady voltage supply. Sort of confirms the AC122 is well and truly brown-bread :/
    IMG_20240404_185849(1)_1.jpg


    oh....my....gawwwwd. Somebody was actually using this with a Sony WMD6C at one point!
    Just imagine the calamity, upset and tears had this woefully inadequate wiring job zapped such a lovely Walkman! I don't know which wire that is that's come loose, but either way it's going straight in the bin!
    IMG_20240404_190346_1.jpg
     
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  3. Valentin

    Valentin Well-Known Member

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    In regard to the supply in the first post, what AC voltage do you get at the output of transformer ? Maybe someone plugged it into a 240V outlet with the switch set to 120V.
    From what I see it seems a simple unregulated supply with a bridge rectifier, filter capacitor and a bleeder resistor across the capacitor.
    The different voltages are probably obtained with different taps on the transformer.

    As for the AC-240 one in second post, that one can work fine if you add a low dropout voltage regulator to it to have an output voltage of 5V or 5.5V.
     
    Last edited: Apr 4, 2024
  4. Chris_D

    Chris_D Active Member

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    I'm just getting a residual 0.5v for each of the 3 output settings on the AC122 Valentin.
    The AC240 is rated for 6v as is the TCD5M, so that one is fine and dandy at 6v.

    Digging a bit deeper into the AC122 and I didn't think to inspect the secondary fuse in that plastic fuse holder first time around. It's rated the same as the primary input fuse @ 1250mA but it looks totally different, coiled at each end with a straight middle section whereas the primary one looks normal/straight.
    They both check ok for continuity so they haven't blown.
    However, the 4 output wires on the output side of the transformer are crispy and look like they have been subject to high temps, so I'm assuming the transformer has overheated or burned out. It doesn't smell like a normal burned out transformer though and I know what they smell like! *chuckle*

    A shame really. Don't have the time, inclination or interest to do a re-wind, so I'm pretty thankful I realised I had the AC240 all along! lol

    DSC_0107_1.JPG DSC_0103_1_1.JPG DSC_0106_1.JPG DSC_0108_1.JPG
     
  5. Valentin

    Valentin Well-Known Member

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    I was reffering to what is shown in second picture of post #2, which looks like it's the AC240 measured but I may be mistaken.
    My point with LDO was in regard to the potential use of this supply (the one measuring 6.76V) with the WM-D6C.
    This is the part which made me think it was about the AC240 and D6C. But later on I read the post again and realised you were actually reffering to the white supply labeled WM-D6C.

    Nonetheless, the same logic would apply regardless of supply used. For the D6C, one needs to use a supply that would have a no load output voltage of 6V or below (prefferably below).
    The no load is important since the CX20084 IC is connected to power at all times, not just when unit is powered on (case in which the voltage will drop under load).

    Out of curiosity, what voltage does the AC240 outputs with no load ?
     

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