K5synth

Update:
Well today I ordered a new inverter from www.DigiKey.com.  I found an
inverter that looks like it will do the job - for those interested it is:

Digikey part #	289-1032-ND  and it only cost $11.90 - not bad.

I am not sure if it will fit exactly in the same slots as the original
inverter so it might require some additional wiring.

Anyway, I had my K5 open to look at the power supply to plan the new
inverter install when my K5 started "humming", and guess what, I now
have a beautiful blue backlight.  It looks great, a very cool blue. 
So it appears my inverter was not bad, but it just has bad solder
joints.  It is working for now but tomorrow I will likely take out the
board and redo all the solder joints.  

Just some additional info I learned in researching backlights and
inverters.  The "brightness" of the backlight is a function of the
voltage and frequency applied to the backlight.  It appears one has a
lot of flexibility in selecting the inverter output voltage and freq.
For example, nightlauch says you can "test" the backlight by plugging
it directly in to a wall socket (120V AC @ 60 Hz here in the US)!  The
higher the voltage and freq the brighter the backlight.   However, the
backlight will "burn out" quicker the higher the freq.  So there is a
trade off, high freq = bright but shorter life.  

Right now my stock inverter is putting out about 102V @ 380 Hz.  I
think the inverter I ordered will put out about 95V @ 540 Hz and
should work with a 3 - 6 V DC input.

Next step, 147k resistors (also ordered from Digikey today).  



--- In k5synth@yahoogroups.com, "nelsonj_sce" <nelsonj_sce@y...> wrote:
> Well I replaced my backlight with one I ordered from
www.nightlaunch.com.
> 
> It took less than two weeks from when I ordered and the parts look
good.  
> 
> Good news/bad news though on my backlight.  
> 
> The good news:  I had no problems removing the LCD, taking out the old
> backlight and sliding in the new backlight.  The new light has some
> wires and a plastic "tab" that kind of gets in the way, so I soldered
> the backlight wires to where the wires connect to the LCD board. 
> Hint:You have to cut the new backlight to size, so make the backlight
> a little longer (say 1/4 inch) than the original to make things easier.
> 
> Bad news: My backlight does not work but I think my inverter is the
> problem.  I am only getting about 1/2 Volt at the output of my
> inverter, and I am supposed to get 120V @400Hz if I understand the
> part correctly.  I tested my inverter before I did the backlight
> install and saw it had low voltage, but I was hoping that my existing
> "dead" backlight was causing the problem (i.e. it was shorted.) I
> guess not because even with the new backlight I get very low voltage.
> 
> Anyway, it looks like I need to get an inverter.  I can get an
> inverter from nightlaunch for $17.99+s/h but it needs 9V DC.  I
> understand the inverter in the K5 uses 5V DC. 
>  
> Q1: Does the K5 inverter use 5V DC?
> Q2: If I measure the voltage on the two wires to the left of the
> inverter, should I get 120V if everything is working? (My Fluke says
> it is good <=1kHz)
> Q2: Does anyone know where to get a compatible K5 inverter and how
> much it will cost?
> 
> Thanks again for all the help.  This group is great.