Re: K5 Repair Issues

--- 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?  
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.  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.