Korg Poly800/EX800 Users

Hey guys,

Been subscribed to here for a while but not posted. All great stuff going on here. Got a poly 800 that I have had for a couple of years and managed to do the moog slayer and ext input (through the noise channel). Also did install the filter slope but removed this.

However it has been working fine until just yesterday actually. Tried to power it on and it just won't turn on. No lights or nothing. However if you switch it on it makes a pop and then just makes ground noise or hum.

I left the power plugged in for an extended duration of time (but the unit was not powered on) and have I messed up a diode or something?

Have not tried C batteries yet but just wanted to know what may have happened.

I have also installed the battery mod and just removed D1 and R1 (well I desoldered a leg from each) as mine is the version that had solder pads but no battery. Also did remove the components that would usually be for the first gen, but I believe this is no issue aside from that all patches are powered by the lithium battery only.

Weird that this has randomly happened.

If you guys have any ideas please give me shout, cheers.

Just thought I would add the power supply I am using is: 300mA unregulated AC/DC adaptor. Also checked I was using the right polarity, which appeared to be working fine. Also works on other devices I have such as a small little casio keyboard and a bigger yamaha one.

Thanks again

On Wed, Aug 21, 2013 at 06:08:10PM -0000, wrezal wrote:

> Just thought I would add the power supply I am using is: 300mA unregulated AC/DC adaptor. Also checked I was using the right polarity, which appeared to be working fine. Also works on other devices I have such as a small little casio keyboard and a bigger yamaha one.

You need a minimum of a 1A power supply. More is fine, as long as it's still 9V
and still the correct polarity. It's very unlikely that a 300mA power supply
will even get it to light up the display.

--
Gordonjcp MM0YEQ

Hey Gordon,

Yeah well it did use to work. It was one where you could change the voltage so 9v wasn't even the maximum. Reckon its a dead power supply then? Does work on other devices at 6v. Going to try a 12v keyboard now and will see if that works.

Cheers,

Dave

Did try the tape method to no avail. Nothing occurred with the tape mode engaged. Just the same noise. Did do a bit of reading about previous threads and apparently could just be me damaging a transistor or something?

Don't currently have a multimeter but I might pop down and get one to be able to check the voltage ratings

Right just had a go with a more hungry keyboard and nope no dice so I think the PSU has gone out (wasn't a great one, just one of ebay)

I will order one and have a go, and then I will know whether or not it really is the PSU. Shook the PSU and sounded like something was lose so maybe I should spend and bit more and get a better quality one. Thanks for responses, if I don't have any luck I will post another message and hopefully we can figure this one out.

Cheers guys,

Dave

On Wed, Aug 21, 2013 at 06:57:24PM -0000, wrezal wrote:

> Hey Gordon,
>
> Yeah well it did use to work. It was one where you could change the voltage so 9v wasn't even the maximum. Reckon its a dead power supply then? Does work on other devices at 6v. Going to try a 12v keyboard now and will see if that works.
>
> Cheers,
>
> Dave

It couldn't have worked properly. The Poly 800 takes a good 600-700mA normally, so using the 300mA supply would have pulled it down to way below the point where the regulators function correctly.

--
Gordonjcp MM0YEQ

On Wed, Aug 21, 2013 at 07:15:38PM -0000, wrezal wrote:

> I will order one and have a go, and then I will know whether or not it really is the PSU. Shook the PSU and sounded like something was lose so maybe I should spend and bit more and get a better quality one. Thanks for responses, if I don't have any luck I will post another message and hopefully we can figure this one out.

Since I have a bunch of 9V DC equipment to run, I use a 9V 10A power supply with the outputs split out down the back of the rack and a few flying leads for other stuff like keyboards. It's amazing how much of a difference a nice quiet switcher can make compared to the cheap crappy ones, or even the unregulated linear supplies...

--
Gordonjcp MM0YEQ

It's funny you say the Poly800 needs that much because in the original manual of my EX-800 it says 300ma minimum obviously I'm using a 1K regulated but there is no reason why it shouldn't work with that,unless the Poly800 is different to the EX-800.