Lamp bypass on Infocus Lp120


2007-10-17 2:10 am
I'm banging my head agains the table trying to figure out how to bypass the ballast in an LP120 DLP projector.

So far I have managed to get the thing to start up with a 100ohm resistor instead of a bulb , but thats not entirely practical as the thing glows red hot and my wife comes home and says 'whats that smell like burning plastic?'

She doens't know I spent lots of money of 'scrap' but I know I can get it to work.

Theres a 5 pin connecter from the ballast to the controller board and the pins 1&2 come from the resistor end of an opto-couper on the ballast so presumable tell the optics that the bulb is on and working. Pin 3 is earth I think, and the other 2 go to pin 2 of the the other 2 Opto Couplers on the Ballast. So they must be telling the ballast when to ignite and something.

When I power up with a bulb or a resistor, theres a delay of 14 seconds before the bulb lights and with no bulb or resistor the display says 'failed to light' after about 10 seconds.

I've tried shorting pins 1&2 but no joy, could it be a timimg issue???

Heres some photos[email protected]

Any advice would be greatly appreciated!!!!




2011-12-12 3:53 am
I have the LP120 projector, giving me a "Lamp did not strike" message. I'm pretty sure it's a bad ballast - "EUC 132 G/11".

Can anyone tell me where I might find a replacement ballast, or what parts I might look to repair on the ballast itself?

I found an identical looking ballast on ebay, but it has a different part number. I can't find datasheets to compare, so I'm hesitant to buy.



2011-12-16 11:09 am
I have a hitachi ED-3170 projector and I recently bypassed the ballast completely (taking the whole ballast out and having it working.) All I did is grounding the pin called "Lamp Mis" going to the ballast. and other 3 is just left unplugged since I took the ballast out.

The 4 pin going to ballast control board is:
1. Lamp on
2. RET
3. Lamp Mis
4. Ecomode

I'm not sure about your projector but check the data sheet for the projector and figer out which pin does what and it will be easier.