20v 1.7a 3-Pin Din Power Supply

[Barnee]

Hi there!

I am really struggling to find the parts I need, so any help would be hugely appreciated.

I need a power supply with a 3-Pin din-style output (image below of the female) rated to 20v, 1.7a DC (image below for more details).

Any electro-wizards know where I can find something like this? Or the parts to put one together?

Thanks for any advice you can give

 

[Alec_t]

Is this any use?
Or one of these?

 

[Barnee]

Is this any use?
Or one of these?

Hi!

Yes, they are useful. The connector is good. The hard bit to get will be a 20v power supply with the matching outputs I haven't found one anywhere that actually has one in stock.

 

[Alec_t]

The hard bit to get will be a 20v power supply with the matching outputs

You'll probably have to rewire the output cable of an otherwise suitable supply.

 

[Barnee]

You'll probably have to rewire the output cable of an otherwise suitable supply.

I'm happy to do that. But (and sorry - I'm a newbie to this), how do I know it will have a suitable output (ie. 3 pin)? I have found a supply that is rated to 20v 1.7a (in the form of a normal speaker power supply - see link), but will it have the necessary outputs?

https://www.amazon.co.uk/Adapter-Su...ie=UTF8&qid=1489510405&sr=8-1&keywords=20v+2a

 

[Alec_t]

The supply in that link is unsuitable on its own. From the label on your digital piano it's clear you need a dual-polarity 20V supply, but perhaps two of those linked supplies could be pressed into service if you're desperate.
Looking closer at the first pic, it seems the pin positions are asymmetric, suggesting the plug/socket may be proprietary . If you can't find a mating plug would you be able to replace the existing socket with a non-proprietary one?

 

[Barnee]

The supply in that link is unsuitable on its own. From the label on your digital piano it's clear you need a dual-polarity 20V supply, but perhaps two of those linked supplies could be pressed into service if you're desperate.
Looking closer at the first pic, it seems the pin positions are asymmetric, suggesting the plug/socket may be proprietary . If you can't find a mating plug would you be able to replace the existing socket with a non-proprietary one?

Just tried to open it up to see if I could access it easily, but with limited success.

I can get it slightly open, but it's one of those ridiculous designs that has electronics mounted on both sides of the part so opening it to a point that allows any reasonable access would require more expertise or a complete disassembly to ensure nothing is damaged.

Are we sure the one at the Maplin link you provided isn't the right one? It does look like the one I have, with one pin smaller than the other 2. Perhaps worth ordering just to trial for the £1.99 price-tag.

Assuming we can get a connector (I can always permanently bodge the wires in place as a last resort), what do you suggest the best option is in order to locate a dual polarity 20v supply? I can try linking two together, but that really does sound dodgy!!

 

[davenn]

what do you suggest the best option is in order to locate a dual polarity 20v supply?

if the manufacturer cannot supply a replacement, and that is probably, you wont find one
your only 2 choices will be to repair the one you have or build a replacement from scratch

either way, you really must open up the PSU you have to see how it's constructed
so open it up and show some photos

 

[Alec_t]

Are we sure the one at the Maplin link you provided isn't the right one?

Not in the least sure. If you can measure the pin sizes and spacing you might be able to get some technical data from DIN/manufacturers datasheets to try for a match.

I can try linking two together, but that really does sound dodgy!!

Not dodgy; just inelegant. For most (all?) switch-mode supplies the output has no ground connection linked with the mains ground, i.e the output is floating. So you'd connect the negative output wire of one supply to the positive output wire of the other supply and treat the connection as "0V".
Incidentally, what happened to the original power supply?

 

[Alec_t]

Here's a cheaper alternative adapter (19.5V), with a higher current rating (an advantage). I'm sure the piano won't miss 0.5V !

 

[Barnee]

if the manufacturer cannot supply a replacement, and that is probably, you wont find one
your only 2 choices will be to repair the one you have or build a replacement from scratch

either way, you really must open up the PSU you have to see how it's constructed
so open it up and show some photos

Unfortunately I don't have the PSU and never did! I found the piano in my dad's attic and it seemed like a really nicely built machine, so I thought I'd have a stab at getting it running. Thoroughly rifled through the attic with no success.

I'm happy to make one - sounds like a bit of fun.

 

[Barnee]

Not in the least sure. If you can measure the pin sizes and spacing you might be able to get some technical data from DIN/manufacturers datasheets to try for a match.

Well perhaps I'll order one just to try. Then at least we've made some progress. If it doesn't fit then we can fairly safely conclude it was a specialist design that no longer exists. In which case it's bodge time.

Not dodgy; just inelegant. For most (all?) switch-mode supplies the output has no ground connection linked with the mains ground, i.e the output is floating. So you'd connect the negative output wire of one supply to the positive output wire of the other supply and treat the connection as "0V".

Could you draw a quick diagram on paint? Not 100% sure what you mean

Incidentally, what happened to the original power supply?

See previous message in reply to davenn

Here's a cheaper alternative adapter (19.5V), with a higher current rating (an advantage). I'm sure the piano won't miss 0.5V !

Can't see the web link

 

[Alec_t]

Sorry, here's the link to a similar one, this time for 20V.

 

[Alec_t]

Here's how you would combine two power bricks.

One problem, if you don't have the original power supply, will be identifying which pins of your piano socket should receive the +20V, 0V and -20V. This will involve some circuit tracing inside the piano. I'd advise making sure of that before investing in power supplies.
Incidentally, power supplies ('AC adapters') in the 18V-20V DC 2-3A range are typically used as laptop chargers/supplies, so should be easy to source. Despite a fair bit of Googling I was unable to find any dual-polarity supplies in that range.

 

[Barnee]

Sorry, here's the link to a similar one, this time for 20V.

Great! I'll take a look

Here's how you would combine two power bricks.

Great! Thank you very much. This makes sense. I'll have to get hold of some stuff to splice the cables.

One problem, if you don't have the original power supply, will be identifying which pins of your piano socket should receive the +20V, 0V and -20V. This will involve some circuit tracing inside the piano. I'd advise making sure of that before investing in power supplies.
Incidentally, power supplies ('AC adapters') in the 18V-20V DC 2-3A range are typically used as laptop chargers/supplies, so should be easy to source. Despite a fair bit of Googling I was unable to find any dual-polarity supplies in that range.

Yeah, I'm a little worried about this. I managed to take some questionable photos through the small opening I made to try and get an idea of what was going on before I gave up for now.. but I think I'll need to dive back in at some point. I'll update when I get some better ones - probably at the weekend

 

[Alec_t]

Have you tried contacting the piano maker directly for any pin-out details?
I looked here, but your piano model isn't listed.

 

[Barnee]

Have you tried contacting the piano maker directly for any pin-out details?
I looked here, but your piano model isn't listed.

I actually have! I sent the guys at that link an email last week and they were really helpful, but weren't able to provide me any technical details on the supply. They sent me over a manual for the piano (link here on my google drive for anyone finding this thread in future - was too big to attach), but it has no info helpful to this situation unfortunately.

 

[Alec_t]

I see from the manual that there are MIDI sockets. The centre pin of each MIDI socket (DIN pin 2) is ground, so if you do a continuity check using a multimeter, hopefully you will be able to identify which one of the three pins of the power socket is ground.

 

[Barnee]

Did a bit of fiddling with it today. Haven't had a chance to open it up again (it takes so long - so many screws in this thing!).

Did what you said and checked pins against centre midi pin to find the ground - turns out it's the outer edge of the connector. None of the pins responded to the check (attached image).

Also got the connector from Maplin in the post. Success - it fits! Now I've just got to work out how to wire up the pins correctly

 

[Alec_t]

Success - it fits!

That's good news.
Hope you can trace the power rail connections. Big electrolytic capacitors may be in evidence on the power rails, so the polarity markings on them may give a clue.