Hacking Sharp PG-F212X projector to ignore burnout bulb

I decided to modify a projector to become a UV exposure unit to sensibilize a photo PCB (photo-resist coated PCB).

Then I bought a Sharp PG-F212X projector with burnout bulb in the MercadoLivre (“Brazilian’s eBay”). Then searched for projects replacing the bulb lamp by LEDs and found these pages:

http://www.instructables.com/id/Convert-A-Projector-To-An-LED-Light-Source/?ALLSTEPS

www.lumenarc.co.uk/forum/showthread.php?13306-InFocus-LP600-Bypass-lamp-check

Based on this page I realized that it is necessary to short-circuit the pins 3 and 4 of the opto-coupler to force the projector to think the bulb is fine. This tip is for projector InFocus LP600. Then I decided to search for the Service Manual of Sharp projector. I found it here: http://elektrotanya.com/sharp_pg-f212x-l_xr-32s-x-l.pdf/download.html

Analyzing the schematic in the service manual I discovered that the opto-coupler should be that D7715 at page 63, because it was responsable by the N-LIGHT signal.

After removing the projector’s top cover I noticed it was possible to short-circuit the pins 3 and 4 of D7715 without disassembling anything more. Then I just used the iron solder to melt solder there and short-circuit it:

optocoupler_shortcircuited

Then after powering on the projector the Lamp indicator turned green indicating that the lamp was working fine. Now the next step will be adapting a UV LED module as light source!

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