problem ballast infocus lp730

This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
I am new of the forum and I hand a great regard to everybody.
My problem is on a video projector Infocus lp730
1) the VPR turns on all the lights and the fans they turn
2) it also ignites the yellow light of the lamp
3) I have replaced the lamp with negative result (the lamp doesn't turn on)
4) I have thought about the power supply
5) being formed the PS of two parts: low tension and HV (BALLAST LAMP) I have effected some measures on the group low tension and I have measured 300 volts to the exit of the group low tension.
6) the tension 300volt enter the group HV but it don't produce the tension to turn on the lamp.
I ask you the question: does someone of the forum have the same problem and you can technically help me telling me which component you is broken on the part HV or him it supposes broken?
thanks to everybody of the forum
I have found one of the two optocouplers that to the measure with multimetro me from a wrong measure.
And' possible that the missed lighting of the lamp is due to this optocoupler?


  • ballast lp730.JPG
    ballast lp730.JPG
    385.3 KB · Views: 76
observing the datasheet I have measured with a multmeter on the course ohm a resistance in comparison to the new P621.
Emitter and collector have to regularly measure an endless resistance.
If you have an Infocus LP730 tell me your defect
My LP730 has all the leds also turned on the green led "lamp"
all the fans work
but the lamp doesn't turn on.
The two optocouplers serve to receive the signals of control of the connector to 3 pins that originate from the mainboard CPU, these signals they serve for giving the consent to the lighting of the ballast HV that then it turns on the lamp.


  • data sheet p621.pdf
    74.1 KB · Views: 111
Hi marketta,
I didn't try to dismantle this because i haven't te necessary skills to open the case; maybe y should send tho a laboratory if I don't wanna crash somethig...

thank you for the opinion, I can see that you are working very well with your proyector.

Sorry for my bad English, i'm writting from Argentina.
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.