I've got an Eiki LC-7000 (aka Sanyo PLC-5500) projector. The lamp power supply failed at some hundred hours of the second lamp - and guess what the owner did? He bought a new one (third one for the projector)... Now I have a projector (which works fine with another light source) and two lamps. I already have a CRT projector so I thought I'll repair this and give it to my boyfriend to play with (maybe he'll stop complaining for a while...) I replaced 4 shorted transistors (2SC4424). Now the ignition seems to work fine, and a blue arc lights in the lamp. However, the lamp never gets the actual operating current. I didn't expect it to be this easy, and traced further. The 4 transistors are driven by integrated optocoupler-driver-IC:s (PS9634), and 2 of them were getting warm and measured some nice zero ohms.
What else should I check? I found only passive components which tested OK, and except the rest of the supply to be fine because of optocoupling. I also think it blew because the first lamp of the projector was used until it exploded causing some damage, so just replacing the semiconductors should fix it. Ordering these rare Japanese semiconductors from the US is a bit pricey, so I'd like to get all of them at once.