A couple of years ago I had a Mk 1 DX7 in the shop that refused to boot.
The usual checks for correct power and clocks showed all present and correct.
The LCD would power up with all pixels on and stay like that.
All the hallmarks of a dead CPU or EPROM.
For some reason I unplugged the keyboard connector and investigated further.
Lo and behold the DX7 booted and went to its preset as normal.
The issue turned out to be a shorted diode in the keyboard matrix, just the one
in the whole keyboard, but enough to scramble the Data Bus and prevent a boot.
Just my 2 cent worth,
John.
hi
there was no complete Service manual for DX7 (first edition)
on the internet.but now it is
i just upload the complete DX-7 first service manual in Files
hope it will help......
--- In vintagesynthrepair@yahoogroups.com, Kashayar Dashtdar wrote:
>
> Hi my friend.
>
> Unfortunately there is no complete Service manual for DX7 (first edition)
> on the internet.
>
> Try these :
>
> 1- Replace all the electrolytic capacitors in the power supply board.
> 2- Send a fresh sound bank from the PC to the keyboard using a midi
> interface.
>
> I hope it will make your dx7 work properly.
>
> Good luck.
> Ciro
>
> On Tue, Mar 6, 2012 at 8:49 AM, alesisfusion8hd wrote:
>
> > **
> >
> >
> > Hi group,
> >
> > I recently bought a first generation DX7 for $ 50. Problem on startup:
> > sometimes starts up OK, sometimes keeps looping, sometimes seems OK but
> > actually frozen.
> > When it starts up OK, I found only garbage in the internal memory, but it
> > works with the cartridge. It does not memorize my settings, and main output
> > seems dead (headphone OK). I've suspected and replaced the battery cell.
> > I was able to run the self tests up to test #5 (analog inputs), but I have
> > no foot controller to complete this stage.
> > I checked the PSU and the voltage source on the main board (+2.5V, +7.5V
> > and +5AV) and everything is OK.
> > I suspect a signal is missing on the sub-CPU (6805), or a defective RAM.
> > I picked up the schematic and the service manual on Dave Benson's site,
> > but it seems to be altered after page 20. All other services manual I found
> > on the web has the same issue. Does anyone have a full copy of it?
> >
> > Thanks,
> > François
> >
> >
> >
>
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Version: 2012.0.1913 / Virus Database: 2114/4858 - Release Date: 03/08/12