Re: Re: K5 Repair Issues

2008/1/14, ink_blot2001 <ink_blot2001-/[email protected]>:
> --- In [email protected], "Antoine Deschênes" <antdes45@...> wrote:
> >
> > Hi Ivan and welcome to the group,
> >
> > 2008/1/14, ink_blot2001 <ink_blot2001@...>:
> > > I'm new to this group, so I would like to say hello to everyone out there!  I purchased
> a
> > > used K5, without a working backlight, a few months ago.  I was forced to program
> with a
> > > flashlight.
> >
> > Is the LCD really this unreadable for some without backlight? I've
> > used my K5 for years this way without problem. Adjusting the contrast
> > doesn't solve anything?
> >
> > > I finally got to a point where I decided to replace the backlight myself.  I
> > > ordered a backlight from one place, and decided to purchase the last version of ROMs
> > > available from Kawai, as the keyboard was using v1.0.
> >
> > I'd be interested to know how much Kawai is selling it, last time I
> > heard, it was about $50. I sell some V1.3 ROM chips for $6 (only Kawai
> > UK has this version, don't even ask about it in other divisions)
> >
> > > The problem started after I installed the new backlight.  After soldering the two
> > > connections, I reinstalled all the PCBs, and turned on my K5, eager to see the "new"
> > > display.  Nothing happened.  I didn't even get any sound!
> > >
> > > The connections I made were clean.  I might have left the iron on the board a tad
> long, but
> > > could overheating a part on the display board cause the entire keyboard to stop
> function?
> > > I double checked to see if I may have created a short, but everything looked fine, and
> the
> > > fuses still looked good.  I did notice what appeared to be rust on the connections to a
> > > raised white box located on the right side of the instrument.  When closed, it would
> have
> > > been located near the PSU.  Is this the inverter?
> >
> > Hi, yes, it's the inverter, and it's always failing about at the same
> > time as the original backlight.
> > The 'rust' you see is probably hardened rosin flux, someone might have
> > already tried to fix the solder joints around the inverter, which are
> > generally cold/cracking.
> >
> > You can find an alternative inverter with matching specs at DigiKey :
> > http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=289-1032-ND
> >
> > Instructions here : http://kfuenf.org/en/k5_hackpage.html
> >
> > > I would love to get this instrument running again.  If anybody could give me any sort
> of
> > > advice, I would greatly appreciate it.  I was really starting to enjoy this instrument, and
> it
> > > would be a shame if it ended up being scrapped for parts.
> >
> > A parts unit? I doubt, everyone's K5 have or had their original
> > backlight and inverter failing. If I find enough time one day, I'll
> > probably be able to make some kits to fix most of the common problems
> > with the synth : Backlight replacement, backlight inverter + adapter
> > PCB, cheap ROM upgrades (currently ordering), new output stage (The
> > noise level is close to a tape deck), etc.
> >
> > Cheers,
> > Antoine
> >
> > > Thanks in advance.
> > >
> > > Ivan
> > >
> >
> I only have a little electrical knowledge, and no scematic for the K5, but are you saying
> that having an inverter go bad would prevent the entire instrument from functioning at all?

The opposite actually.

The schematic isn't that important for the inverter. Now that I have a
working digital camera, I could take a picture of the power supply PCB
to show you how to connect the new inverter to the PCB.

> I thought it would only prevent the display from working.
>
> As per the comment about how dark the display is without the backlight, it might be
> readable in a better lighted room.

Probably, I always use my K5 under daylight / direct light, I never
thought it could be usable in the dark.

> Additionally, I have a multi-tier keyboard stand with a
> Poly-61 sitting above it, as it is lighter than the K5.  This also places a shadow over the
> K5.
>
>
>
>
> Yahoo! Groups Links
>
>
>
>


-- 
Antoine Deschênes