I knew this one was going to be difficult as the previous owner had a £700 quote for repairing it. The fault was the inverter which told the projector it was on but didn't ignite the lamp.
After an entire day staring at the inverter schematic and testing every single component possible I finally decided on a different solution involving a lunchbox and a load of wires :?
I tore apart an old phillips projector, which incidentally had an almost new 200W UHP lamp (which just so happened to fit in the Hitachi after swapping the housing). Unfortunately the inverter was 1cm too wide to fit in the projector which is where lunch box came in.
I've hooked up the 400V DC connection to the inverter, figured out how it was controlled and wired up the old logic input. I also extended the lamp supply using double insulated cabling (at ignition there's 25,000 volts going through it 😛 ), put the lid back on and fired it up.
The results were awesome!
Not only was it nice and bright but this thing is an LCOS projector with a resolution of 1365 x 1024! LCOS is sort of like a cross between DLP and LCD. Rather than using rotating mirrors to control light it uses an LCD situated on a mirror with the controlling electronics behind. This means very high pixel fill and no 'chicken wire' effect. Since there's 3 LCOS panels there's no rainbow effect.
You can see how fine the image is in the picture above, it's easily the best quality image i've seen although not as bright, or perhaps vibrant as some of the decent LCD projectors i've come across (in particular the LP790HB).
After an entire day staring at the inverter schematic and testing every single component possible I finally decided on a different solution involving a lunchbox and a load of wires :?
I tore apart an old phillips projector, which incidentally had an almost new 200W UHP lamp (which just so happened to fit in the Hitachi after swapping the housing). Unfortunately the inverter was 1cm too wide to fit in the projector which is where lunch box came in.
An externally hosted image should be here but it was not working when we last tested it.
I've hooked up the 400V DC connection to the inverter, figured out how it was controlled and wired up the old logic input. I also extended the lamp supply using double insulated cabling (at ignition there's 25,000 volts going through it 😛 ), put the lid back on and fired it up.
The results were awesome!
An externally hosted image should be here but it was not working when we last tested it.
Not only was it nice and bright but this thing is an LCOS projector with a resolution of 1365 x 1024! LCOS is sort of like a cross between DLP and LCD. Rather than using rotating mirrors to control light it uses an LCD situated on a mirror with the controlling electronics behind. This means very high pixel fill and no 'chicken wire' effect. Since there's 3 LCOS panels there's no rainbow effect.
An externally hosted image should be here but it was not working when we last tested it.
You can see how fine the image is in the picture above, it's easily the best quality image i've seen although not as bright, or perhaps vibrant as some of the decent LCD projectors i've come across (in particular the LP790HB).