Re: K5 Repair Issues

Hi Ivan and welcome to the group,

2008/1/14, ink_blot2001 <ink_blot2001-/[email protected]>:
> 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
>