Question about LG RD-JT91 Multimedia Projector

9 Answers

All lamps are flashing

When the power cord is connected, all lamps flashing, and nothing happens. Try to wait for a hour but with no difference. Is there any way to reset the projector? It's a year old, and about 170 hours used.

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  • pmmms Nov 13, 2007

    all lamps flashing, and nothing happens

  • Anonymous Mar 22, 2014

    I have an Optoma HD80 projector which is three years old and has developed this fault. When plugged in it goes through all blue LED's flashing self-test then only Power LED is on as normal. When Power switch is pressed, the usual noises start, fan, color wheel etc, the lamp comes on at start up intensity and shielded then everything stops, all noises stop, lamp goes out and all the blue LED's flash and it stays in this condition. It will not power off by the power switch and after pulling the mains plug leaving 15 mins and try again it is exactly the same. There are no red LED's only flashing blues, the lamp is about 150 hours old and an original Optoma expensive replacement
    Any ideas please

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In PSU, on the secondary side of switch supply there are electrolytic capacitors: for 13 V is 470uF/25V and for 5 (and subsequent 3V) is 1000 uF/16V. Those capacitors in some devices from this series use to break (why? I don't know: maybe cheep quality). Check voltage on rectifiers outputs with oscilloscope: if there are not constant voltage on one of them you should replace it with the new one (of course good quality). I've got the same failure subsequently on 5V supply (this reparation was done by LG service, but when I asked them they answered they replaced mother board - bull shit!) When the same "flashing" problem after guaranty occurred again, I had found soldering traces on the cap on 5V!And guess what - it was cap with a different brand than others.



This solution is maybe only for el-geckos, but no service wanted to repair my quite new, still worth something projector (not in Sweden any way). If you can’t do a job your self you still can ask some handy friend which know how to solder parts. Be careful! There is high, dangerous voltage on primary, so you must know what you are doing!



I'm sometime very irritated: that capacitor cost less in bulk than 2 cents each! But the ordinary people must buy a new projector because of lack of service!

There is PSU diagram:All lamps are flashing - 1af7f4a.jpg

Posted on Dec 11, 2007

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GREAT! Thank you so much, BruceRob and Beeblebrox! I was able to revive my RD-JT92 with your help.
To help others, here is a picture of the capacitor that I changed to get it running again: www.cliff.de/galerie/RD-JT92-inside.jpg

Cheers, 

Cliff

Posted on Aug 06, 2008

  • mely cas
    mely cas Oct 29, 2014

    Hi All,I come back on this old post. Does anyone still has this picture that shows which capacitor had to be changed. The link is dead and I would really appreciate to get the image. Thanks. Syl

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I experienced the same flashing lights problem. Followed BruceRob's advice to fix the PSU board. To open the case, you unscrew all the screws marked with arrows on the case, plus a little hidden screw inside the lip of the connector flap cover! It is akward to unscrew this one. You have to remove the main PCB by undoing its 6 screws and carefully unclipping each of the cable connectors; the flexi-cable just pulls out. Now you have access to the PSU PCB. Undo 2 screws and the 2 hex pillars. Remove the PCB carefully - it might still have lurking high voltages on it! It disconnects from the the high voltage unit by unplugging the one cable.

Now you can check the caps that BruceRob referred to. In my case, the version seems a little different, i.e. the 5V section used a 220uF cap (the culprit in my case) and a 470uF cap instead of the two 1000uF ones. I replaced all four of the large electrolytic caps on the 13V and 5V sections for just in case.

Incidentally, if you measure the PSU outputs under no load conditions, it seems to work fine, but if you attach a load, it starts to oscillate. I used a 12V 120ohm bulb as test load on the 13V and 5V sections. After my fixes, the 13V section only delivered about 11.5V, but the 5V and 3.3V were fine. The 13V is intended mainly for the fans I think and they worked fine afterwards.

Before closing up, I blew out all the collected dust which gathered over the 2500 odd lamp hours of my unit. Buying replacement caps for all electrolytics on the PSU board cost me about R5 (ZAR).

Posted on Apr 17, 2008

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Hi All,
I come back on this old post. Does anyone still has this picture that shows which capacitor had to be changed. The link is dead and I would really appreciate to get the image.
Thanks. S.

All lamps are flashing - e9e6354c-6d38-4c21-82da-7f9aed2043e6.jpg

Posted on Oct 29, 2014

  • mely cas
    mely cas Nov 02, 2014

    I get the orginial image. Here it is. Very helpful because I had exactlythe same problem nd was able to fix it.

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Thanks for posting this great fix & the detailed descriptions!
I just managed to get my old RD-JT91 by replacing all 4 caps. Just a few cents investment - and a fully functional projector.

Thank you so much!!!

If anyone finds this helpful, here is the service manual - it contains some diagrams and part lists.
http://diagramas.diagramasde.com/otros/LG%20RD_JT91%20DLP%20PROJECTOR.pdf

Posted on Jul 29, 2014

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Thanks guys!
Amazing, one of my friends (with more skills into electronics and stuff) managed to make my projector come to life again with help of your great explanations, drawings and pictures. It was quite tricky but after a few hours we put all parts together - and it worked!

Again, thanks a lot for your help.

Posted on Oct 14, 2008

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This site is fantastic.
Many thanks for the the detailled explanation of the problem.
By changing the capacitors my projector works properly again. The counter of lamp life time displays: 4089 h.

GRACIAS! Bravo!

Posted on Jul 23, 2008

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Where do you buy a power supply for this kind of projector?

Posted on Feb 25, 2007

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Yes I had the same problem for a while ago. It was a defect power supply

Posted on Feb 23, 2007

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Try to do the following, it didn't work for me but it may work for you...


The STANDBY light will flash if an issue is detected within the television. This can sometimes be resolved by simply following the steps below to reset the television.
  1. Turn off the television. IMPORTANT: For a projection television that uses an internal lamp, wait 5 minutes after turning off the television to allow the lamp to cool before continuing with the following steps.
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Please describe the status of the LED indicator. No LED would indicate a failure of the power supply. I can help you with that.
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If it is the power supply, no lights at all, I can get you running again. These units have fragile power supplies that can burn out with the slightest power surge. A UPS goes a long way to save future headaches.

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Try to reset first if nothing happens we proceed another solution;

Resetting the TV

Some TVs have a reset button. If available and accessible, try using the reset buttons before using the steps below. Using the reset buttons can saved time.
1. Unplug the TV power cord from the power outlet for 3 - 4 hours.
2. Unplug any connected devices (DVD, Set-top boxes, etc...)
3. Press and hold the TV power button for five seconds.
4. Plug the TV power cord back into the power outlet and turn on the TV.
5. Open the on-screen menu to confirm that the TV is responding again.
6. Turn off the TV and reconnect the devices.
7. Turn on the TV.

hope this may help;

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Lights flashing


Try the steps mentioned bellow

Unplug the power cord from the All-In-One as well as the power outlet when there is still power in the All-In-One. and wait for atleast 1Min
Plug the power cord directly to a wall outlet without surg protector. (if possible connect it to a different power outlet)
Before connecting the power cord to the All-In-One press and hold the # and no 6 button and then insert the power cord, do not release the keys
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Lamp Replacement Procedure:
1. Press the POWER button to turn off the power.
2. Wait for about 1 minute until the cooling fan stops.
Note:
The lamp cooling fan will continue to operate for about 1
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8. Install the new Lamp, and tighten the Screw.
9. Install the Lamp Cover, and turn the Knob to the right.
10. Install the Front Cover Unit.
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Be sure to reset the Lamp time to "0" after replacing the new
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1. Plug in the AC Cord, and turn on the power by pressing the
POWER button.
2. Press and hold the VOLUME DOWN button on the unit and
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in power on condition.
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