Problem with power supply (I think)

The Yamaha SY99 is a synthesiser combining frequency modulation synthesis (branded as Advanced FM) and sample-based synthesis (branded as Advanced Wave Memory 2) and the direct successor to Yamaha's SY77/TG77

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kiaya611
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Problem with power supply (I think)

Unread post by kiaya611 » Sat Sep 02, 2017 10:52 pm

I bought this SY99 in about 1991 (I think( and after years of use, it stopped working. It was stored for years and now I am trying to see if I can get it back up and running. I know I have to change all of the batteries, those on the 2 main boards and the 2 on each expandable memory. I was thinking of using battery "sockets" to solder to the boards and then I could just change the batteries as needed.

Then I need to try and figure out of, in fact, the power supply died or not. Is there a way to check and see if that is working correctly? I would hate to dump it even though I am planning on getting a Tyros 5, but that will be a while.

Thank you in advance for your help.

Steven


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Re: Problem with power supply (I think)

Unread post by Saul » Sun Sep 03, 2017 12:34 am

Hi Steven

Didn't you already replace the batteries? Also you checked the voltages going to the boards and they were ok? It's in your thread from 2009 here:
http://yamahamusicians.com/forum/viewto ... 160#p13160


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kiaya611
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Re: Problem with power supply (I think)

Unread post by kiaya611 » Sun Sep 03, 2017 1:23 am

Your memory/system memory is much better than mine. I did replace the batteries, I do have the extended memory (all of it and didn't change the batteries there at that time), however, I removed the extra memory at this point. I am going to assume that it did not work before I changed the batteries because that would have caused me to look deeper. When I tested for electricity, I am sure the figures I got were actual figures I seem to remember that I only got them at the power supply and not further along the circuit. I am re-visiting this, I suppose as a last ditch effort before I get rid of it as something that simply has died. It has been so long now, that I don't remember how to use it and although I did enjoy it and it was quite amazing in its time, technology has advanced so much since then that if I can get money ahead, I guess I should just cut my losses and buy a Tyros 5 (76-key). I figured this was a long shot and I was right. Sorry to have bothered you (again) on this topic. Steven


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Re: Problem with power supply (I think)

Unread post by Saul » Sun Sep 03, 2017 1:36 am

It's not a bother Steven, just didn't want you having to repeat work you had already done. It was back in 2009 after all. I'm pretty sure I can't remember much about what I was doing then.

Would be a shame to let the SY99 go when it might be something simple that is preventing it from working. There are not that many of them about so if you can bring it back to life, even if you don't intend to keep it you would at least get some money back from the Tyros 5 outlay...another fantastic keyboard by the way :)


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Re: Problem with power supply (I think)

Unread post by kiaya611 » Sun Sep 03, 2017 2:55 am

I used to know integrated circuits very well, but for a very long time now, if it goes past discrete electronics, I can't seem to follow the traces like I once could. I just don't know where to start to start ruling things out. I guess with our organization, I have concentrated so much on old electronics that I have forgotten what I once knew and when confronted with it, I just draw blanks. I can do great with tubes and early electronics. Add an IC and you would think I never saw a light bulb before :) I would like to get the SY99 going again...I had a great time with it a very long time ago. My friend with the Tyros 4 keeps pushing me to get the 5...LOL I just tell him to write the check :)


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Re: Problem with power supply (I think)

Unread post by Saul » Sun Sep 03, 2017 10:04 am

Ha ha, yes the Tyros 5 is not exactly a "budget" instrument! Well worth the money though.

Like most things in life if you don't use the knowledge all the time it can fade from memory. It's still there of course it just takes a lot longer to pull out and often you need to do some research to refresh what you know. We are all the same to some extent.

If the batteries are fine and we can assume they are since you replaced them in 2009 and have not used it since and your not getting any power at all through, so no display and nothing is working then the psu is the first thing to check out. If all the voltages are correct and coming out to the boards then at least it eliminates that as a possible cause. Your then down to either a bad connection further along or component failure.

I'm pretty sure it would be worthwhile getting a local repairer to take a look. The SY99 tends to hold it's value well and as I say there are not many about even in the USA. You could get $5-600 for it in good working condition so I think it would be worth the investment to get it up and running.


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Re: Problem with power supply (I think)

Unread post by Miks » Sun Sep 03, 2017 4:16 pm

Hi kiaya611,

the SY99 uses a 'common' transformer - it's no switching power supply :)

There are several fuses on the psu's pcb - please check them for continuity (with MAINS unplugged!)

The psu serves +5 Volt, +12 Volt and -12 Volt. These voltages are present even without a load (if MAINS are plugged in & the synth is switched ON) - you may disconnect the connectors CN3 - CN4 - CN5 - CN6 - CN7 and CN8 and measure if the voltages are correct (on psu pcb). The psu is not adjustable.


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Re: Problem with power supply (I think)

Unread post by Derek » Sun Sep 03, 2017 7:12 pm

I agree with Miks.

If you want a guide on battery replacement (with holders), then check out http://xfactory-librarians.co.uk/guides.html which covers batteries along woth other common SY99 issues like floppy drives and display.


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