DLPLCR4500EVM: Broken blue led? Projecting yellow not white

user6072213

Part Number: DLPLCR4500EVM

Hi!

I received the DLPLCR4500EVM yesterday and started testing it today. Everything seemed to be working fine until, all of a sudden, the white colors turned yellow. After some further testing, it seems like it can't project blue colors at all (I tested using the led selection in the provided GUI). Thus, I think the blue led in the optical engine is broken. How should I proceed?

Ps. I have already been in contact with customer service who told me to make a post here.

- Ole

over 4 years ago

0 Kyle Rakos over 4 years ago

TI__Mastermind 20045 points

Hello Ole,

Could you try individually selecting the red, green, and blue LEDs in the GUI and share the results? If the blue LED doesn't turn on please try probing TP64 (the blue LED anode) and TP65 (the blue LED cathode).

Thanks,
Kyle

0 Hirak Biswas over 4 years ago in reply to Kyle Rakos

TI__Genius 10925 points

Hi Ole,

Do you still need the answer to your question? I'll be temporarily closing this thread due to inactivity, you can reopen anytime.

Thanks & Regards,

Hirak.

0 user6072213 over 4 years ago in reply to Hirak Biswas

Prodigy 40 points

Hi Hirak,

It's quite busy over here, so I have yet to probe the projector. Hopefully, I'll find time to do it this week. Appreciate if you don't close the thread just yet!

- Ole

0 Hirak Biswas over 4 years ago in reply to user6072213

TI__Genius 10925 points

Hi Ole,

Unfortunately inactive threads need to be closed after a few days but you can take your time to experiment. When you're done, just post a reply to this thread and it will be automatically reopened. Thanks for your cooperation!

Thanks & Regards,

Hirak.

0 user6072213 over 4 years ago in reply to Kyle Rakos

Prodigy 40 points

Hi Kyle,

Using the GUI and selecting the three colors, both red and green works as expected, but no light leaves the lens when I select blue. Probing the blue LED anode and cathode showed a voltage of about 310 mV, to compare I also measured the voltage over the green LED to 3.05V.

Ole

0 Hirak Biswas over 4 years ago in reply to user6072213

TI__Genius 10925 points

Hi Ole,

It seems like the LED may be damaged. Just to be sure, can you interchange the BLUE and GREEN LED connectors? I.e., plug in the BLUE LED socket where the GREEN LED socket is plugged in and vice versa. Now try running again. If the green LED turns on, but the blue LED doesn't that means indeed the blue LED is damaged. If you observe the opposite, that denotes some problem with LED Driving circuit.

Thanks & Regards,

Hirak.

0 user6072213 over 4 years ago in reply to Hirak Biswas

Prodigy 40 points

Hi Hirak,

After interchaning the two, the LCR projects blue when green is selected in the GUI and nothing when blue is selected. Thus, as you say, probably a LED driving circuit problem. How should I proceed?

Thanks!

Ole

0 Hirak Biswas over 4 years ago in reply to user6072213

TI__Genius 10925 points

Hi Ole,

Could you kindly probe the BLU_LED_EN and LEDB_PWM lines to make sure the signals are coming properly?

Thanks & Regards.

Hirak.

0 Hirak Biswas over 4 years ago in reply to Hirak Biswas

TI__Genius 10925 points

Hi Ole,
Do you still need the answer to your question? if not I'll be closing this thread due to inactivity, you can reopen anytime.

Thanks & Regards,

Hirak.

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DLPLCR4500EVM: Broken blue led? Projecting yellow not white