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2007-10-21 by . g . n . w .
Hello Folks, I recently acquired a free DX7FD-II, and it has a dead power supply board. There is no voltage at any of the outputs. The switch and on-board fuse both test OK. Does anyone know of a source for replacement boards, or have any suggestions on testing this one further? I have a multimeter and scope, but I'm not clear on what to check. Any thoughts or suggestions would be appreciated! Thanks, George
2007-10-21 by jim
Hi George ! If that can help you, I've a .pdf document of the whole schematics of the DX7, with the value of componants. let me know if you want it, I can send it by mail jean-marie
2007-10-21 by jim
As this can be usefull to other guys, I posted the DX7 schem in the file section. enjoy ! jean-marie
2007-10-21 by painintheamp
--- In vintagesynthrepair@yahoogroups.com, "jim" <leman@...> wrote: > > As this can be usefull to other guys, I posted the DX7 schem in the > file section. > enjoy ! > > jean-marie > THANKS Jean-marie!!! , Merci - vous , even
2007-10-22 by synapticdistortion
--- In vintagesynthrepair@yahoogroups.com, "jim" <leman@...> wrote: > > As this can be usefull to other guys, I posted the DX7 schem in the > file section. > enjoy ! Thanks for posting that, Jean-marie. Unfortunately, mine looks to be a bit different from those schematics. Perhaps they are only representative of the original DX7, not the FD-II model. The power supply from this one is all on one circuit board, and there is only one fuse. One thing that I've noticed is that there is a hard, tan-colored substance at the bottom of several of the caps. I can't tell if it's leakage, or some sort of thermal material that was placed there during manufacturing. The caps in question otherwise look fine (no bulges or splitting).
2007-10-22 by narfman96
I posted the DX7II power supply component view and parts listing in the files section. There are several boards listed for the U.S. Canada and Europe. I don't have the schematics. I didn't include Japan. The caps can leak but like you say they usually swell. I have digital pictures of this. C1, C11, C23, and C24 are the worst for leakage in the U.S. model. If the whole supply is dead check the bridge rectifier first. Then the transformer. HTH, Fran --- In vintagesynthrepair@yahoogroups.com, "synapticdistortion" <atonal@...> wrote: > > --- In vintagesynthrepair@yahoogroups.com, "jim" <leman@> wrote: > > > > As this can be usefull to other guys, I posted the DX7 schem in the > > file section. > > enjoy ! > > > Thanks for posting that, Jean-marie. Unfortunately, mine looks to be > a bit different from those schematics. Perhaps they are only > representative of the original DX7, not the FD-II model. The power > supply from this one is all on one circuit board, and there is only > one fuse. > > One thing that I've noticed is that there is a hard, tan-colored > substance at the bottom of several of the caps. I can't tell if it's > leakage, or some sort of thermal material that was placed there during > manufacturing. The caps in question otherwise look fine (no bulges or > splitting). >
2007-10-22 by GB
The goopy stuff around the caps is just glue to keep them in place.
2007-10-22 by PeWe
Hi George !
If that can help you, I've a .pdf document of the whole schematics of
the DX7, with the value of componants.
let me know if you want it, I can send it by mail
jean-marie
2007-10-22 by Roy J. Tellason
On Sunday 21 October 2007 22:20, synapticdistortion wrote: > One thing that I've noticed is that there is a hard, tan-colored > substance at the bottom of several of the caps. I can't tell if it's > leakage, or some sort of thermal material that was placed there during > manufacturing. The caps in question otherwise look fine (no bulges or > splitting). That's a goop that they use to put the caps in and hold them in place until they can be soldered, very common in stuff of japanese manufacture. But there's a gotcha -- as the stuff ages, it changes, gets darker, _and gets conductive_! If it's a light tan in color you should probably be okay, but if it's dark brown you might want to scrape it off. Found that bit of info at repairfaq.org... Power supply troubleshooting is pretty straightforward. No outputs? Check your power going in. Make sure you have AC at the input to the transformer. Check for AC at each secondary winding coming out. If that's there, then check for DC on the other side of each rectifier present. When you don't find what you're expecting to find, then you start digging a little deeper. -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, a critter that can be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin
2007-10-23 by pcbye111
Greetings: I have all the PS parts in stock to rebuild the PS in a MkI and a MkII, along with most other Yamaha's and BB's. All the parts are new/fresh OEM Nichicon Radial and Snap CAPS. I also have all the other parts, with the exception of transformers. For the MKII, I think I have one or more PS Boards refurbed in stock that I can do an exchange also, or I can rebuild yours for you. Contact me off line for the prices. I am really cheap, so rather than doing you own home work or re-work for that matter, just drop me a note and I will get you going again. Best regards; Peter pcbye2@...
2007-10-23 by Scott Rider
That is glue. Tall parts were generally glued down so their high center of gravity wouldn't end up cracking the board or otherwise weaken their connection to the traces/pads. Crow /**/ synapticdistortion wrote:
> > > One thing that I've noticed is that there is a hard, tan-colored > substance at the bottom of several of the caps. I can't tell if it's > leakage, or some sort of thermal material that was placed there during > manufacturing. The caps in question otherwise look fine (no bulges or > splitting). > > >
2013-09-28 by <kloopy@...>
I had an issue with power supply on my DX7 MK1 and it was dry joints on low power output. Hope that may help someone.
K
>
>
> One thing that I've noticed is that there is a hard, tan-colored
> substance at the bottom of several of the caps. I can't tell if it's
> leakage, or some sort of thermal material that was placed there during
> manufacturing. The caps in question otherwise look fine (no bulges or
> splitting).
>
>
>
2013-09-29 by <narfman96@...>
The mk1 power supply gets quite warm. This also can lead to bad solder connections.
I had an issue with power supply on my DX7 MK1 and it was dry joints on low power output. Hope that may help someone.
K
>
>
> One thing that I've noticed is that there is a hard, tan-colored
> substance at the bottom of several of the caps. I can't tell if it's
> leakage, or some sort of thermal material that was placed there during
> manufacturing. The caps in question otherwise look fine (no bulges or
> splitting).
>
>
>
2013-09-30 by <nico678@...>
The mk1 power supply gets quite warm. This also can lead to bad solder connections.
I had an issue with power supply on my DX7 MK1 and it was dry joints on low power output. Hope that may help someone.
K
>
>
> One thing that I've noticed is that there is a hard, tan-colored
> substance at the bottom of several of the caps. I can't tell if it's
> leakage, or some sort of thermal material that was placed there during
> manufacturing. The caps in question otherwise look fine (no bulges or
> splitting).
>
>
>
2013-10-02 by Roger J
Typically the feedback cap drys out. It is typically 22uf or 47uf in this circuit. Other caps may also be going south. This is also a good time to improve the filtering by bumping up the values of the filter caps a bit too!
>________________________________ > From: "narfman96@..." <narfman96@...> >To: vintagesynthrepair@yahoogroups.com >Sent: Sunday, September 29, 2013 6:00 AM >Subject: [vintagesynthrepair] RE: Dead PS board in DX7 > > > > >The mk1 power supply gets quite warm. This also can lead to bad solder connections. > > >---In vintagesynthrepair@yahoogroups.com, <kloopy@...> wrote: > > >I had an issue with power supply on my DX7 MK1 and it was dry joints on low power output. Hope that may help someone. >K > > >---In vintagesynthrepair@yahoogroups.com, <oldcrow@...> wrote: > > >That is glue. Tall parts were generally glued down so their high >center of gravity wouldn't end up cracking the board or otherwise weaken >their connection to the traces/pads. > >Crow >/**/ > >synapticdistortion wrote: > >> >>>> >>>> One thing that I've noticed is that there is a hard, tan-colored >>>> substance at the bottom of several of the caps. I can't tell if it's >>>> leakage, or some sort of thermal material that was placed there during >>>> manufacturing. The caps in question otherwise look fine (no bulges or >>>> splitting). >>>> >>>> >>>> > > >