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Thread: Panasonic PT-AE700 LCD projector Power Supply Issue

  1. #1
    Junior Member allspark's Avatar
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    Default Panasonic PT-AE700 LCD projector Power Supply Issue

    Hi there,
    This post is intended for those that are not afraid to apply a soldering iron to their beloved projector and have sound electronics knowledge.

    Note: Be careful and do it safe. Lethal voltages are present. The responsibility is all yours...

    I bought a defective Panasonic ae700 projector on ebay. The described fault, no standby light no sign of life...

    I confirmed that it is indeed the power supply module that is faulty.
    As this was supposed to be a cheap buy for the occasional use I certainly did not want to spend AU$200++ for a new module.

    Unfortunately, the circuit contains 2 special modules and off course it had to be one of them

    The module MR20T is a feedback generator for the SMPS. It serves 2 functions.
    - regulate the output based on the 14.6V
    - selectively rectify the 6V transformer winding to produce 3V3.

    You will find that the 14.6V regulation is still being "attempted" but is somewhat screwed up.
    The other voltages also "hover" lower than usual. The 3V3 can be as low as 1V or not present at all.
    Buzzing can be heard as well.
    Before you waste your time, this is what you need to confirm. Just measure what is supplied from the ribbon cable to the main board.
    Normally you get:
    14.6V
    17V
    6V
    3.3V
    The rest are control and GND wires.

    So you have spotted some life in the power supply dungeon?
    Time to unplug the projector and wait 10min to let all the HV discharge.

    Then start peeling off the layers of ducting and screening. A magnetic screwdriver is recommended.
    You need to undo the screw holding down the lamp supply on the left to be able to pull out the front plastic ducting of the main power supply.

    The idea of this mod is to disable the internal 3V3 regulator/rectifier and just let the module do the 14.6V regulation job.
    The 3V3 regulation will be done externally by a low drop linear regulator.
    The tracks to the power input and output 3V3 of the MR20T have to be cut.
    The output is then shorted to GND to tell the regulator to 'shut up'.
    The little leaded filter inductor has to be removed, this will provide the tapping points for the linear regulator.
    Now:
    - install a 3A Schottky diode from the now isolated transformer output to the 1000uF 10V capacitor (the isolated 3V3 track). I used a HER303.

    - Solder the Linear regulator to the screen for heat sinking. I applied a tiny bit of heat transfer compound and pushed it down flat while soldering the tab to the screen with a BIG soldering tip.

    - Connect a 47uF cap or higher to the output of the regulator and at least a
    100nF ceramic cap to the input. You must have at least 47uF otherwise
    the regulator can not work properly!!!!
    Regulator MIC29300 in TO220 package. Farnell# 121-3487

    - The last modification is the primary current sense.
    Because of the linear regulator the PSU has to produce a few more Watts.
    The limits are adjusted very tightly so we must relax this setting by soldering a 330R 0805 resistor across the filter cap.

    It is best to check for shorts, especially where the tracks were cut. Just for sanity!!

    - Finally connect 3 short wires as per photo to the linear regulator.

    Note: I have kept every part away from the isolation barrier so no safety is compromised. That includes the wires!!!

    Install the board with the screws and connect the input power plug to the board only. ( The big one with 2 wires on the right).

    Connect a little load of no less than 10mA ( a LED and resistor) to the 3V3.
    You can stick the wires in the connector.
    Power up, and measure the rails.

    !!!!!DO NOT TOUCH THE HEAT SINK ON THE PCB THEY ARE LIFE AT 400V!!!!!

    You should now measure:

    14.6V
    17V
    6V
    3.3V

    If so, disconnect the power and have another cup of coffee while the HV is discharging.

    Reassemble the projector.

    Enjoy it as I do...



    Detailed power supply modifications:


    Installed regulator:



  2. The Following 4 Users Say Thank You to allspark For This Useful Post:

    best4less (28-12-10),BMW-Driver (04-01-11),Oscar (27-12-10),redfed (07-05-11)



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    Default Pt-ae700e

    hi
    I have sent you private messages and photo
    thanks

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    Senior Member Oscar's Avatar
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    Default

    Great informative and detailled post Allspark
    Welcome to Austech

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    Default

    hi Oscar
    I am Italian and I don't speak English.
    You can kindly be more precise
    Allspark has responded me in private 2 times and I doesn't now have news of him anymore
    thanks to whom the problem of my PT-AE700E resolves me
    a regard

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    Default Pt-ae700

    Hi, i will update my Firmware to V1.07. The Cable have i build myself. But im looking for the Adjustment tool to test my AdapterCable. Can you help me please? A Downloadlink or an PM was great. Many Thanks!

    PS. My Powermodule was defective, ich bought a new from Panasonic Germany, it costs 106 Euros, but my Panny works great.

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    Quote Originally Posted by BMW-Driver View Post
    Hi, i will update my Firmware to V1.07. The Cable have i build myself. But im looking for the Adjustment tool to test my AdapterCable. Can you help me please? A Downloadlink or an PM was great. Many Thanks!

    PS. My Powermodule was defective, ich bought a new from Panasonic Germany, it costs 106 Euros, but my Panny works great.
    Why are you screwing with the firmware? on those suckers it can be a nightmare!! get it wrong and you'll have to replace the main pcb, eg very expensive and will be cheaper to replace!
    When I explained to the guy what avatar I wanted, that wasn't what I meant!

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    @ iwacelect
    It worked, the firmware is now updated to V.1.07.I tried to update, because with V.1.03 always occurred HDMI flashes, now they are gone. The Panny PT-AE700E is working better than before. It was very easy to update the firmware, using the D-Sub15 VGA port. If someone to help or has questions, I can help you.

    Greetings from good old Germany
    Last edited by BMW-Driver; 04-01-11 at 08:46 PM.

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    Quote Originally Posted by BMW-Driver View Post
    @ iwacelect
    It worked, the firmware is now updated to V.1.07.I tried to update, because with V.1.03 always occurred HDMI flashes, now they are gone. The Panny PT-AE700E is working better than before. It was very easy to update the firmware, using the D-Sub15 VGA port. If someone to help or has questions, I can help you.

    Greetings from good old Germany
    well done, dont get me wrong I've done a shitload. BUT wouldn't suggest it for the un-educated/inexpierienced

    great for you BMW, all you've got to now is keep the dust from killing the blue LCD....

    awaiting update in future...
    When I explained to the guy what avatar I wanted, that wasn't what I meant!

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    Default

    Guys, i have this projector and had it in storage for ages as it does not work, everytime its turned on power light flashes amber then turns green for a few seconds then flashes green and turns off, it repeats this process over and over.

    Occassionally i get to see screen for a few seconds.

    Globe appears to be fine.

    Any ideas what may be the cause.

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    Thanks to this thread and the service manual, fixed the 3.4V power supply failure. The failed MR20T1 is just a 3.4Volt rectifier/regulator module. It has no part in the overall regulation of the Power Supply.

    Used the mod described in the first post and all is well again.

    Anyone need help feel free to PM me.

    rgds Damon

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    Hi,

    i know this post is old but i have a question concerning the pt-ae700 power supply. I have the same problem decribed by allspark. The 3.3v voltage is out. So i made the modification he described. I now get the 3.3 voltage. BUT (and this is my problem) all the others voltages are present (14, 17 and 6) but they are not stable. They oscillate from 0 to the correct voltage with a frequencie of about 1 second. Just for information, the 3.3 voltage is stable.
    If someone can help, i would really appreciate.

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    Quote Originally Posted by clem77 View Post
    Hi,

    i know this post is old but i have a question concerning the pt-ae700 power supply. I have the same problem decribed by allspark. The 3.3v voltage is out. So i made the modification he described. I now get the 3.3 voltage. BUT (and this is my problem) all the others voltages are present (14, 17 and 6) but they are not stable. They oscillate from 0 to the correct voltage with a frequencie of about 1 second. Just for information, the 3.3 voltage is stable.
    If someone can help, i would really appreciate.
    Sounds like something shorted out, and the power supply is folding back trying to protect itself. Let me dig out the circuits over the next few days and I will get back to you.

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    Quote Originally Posted by redfed View Post
    Thanks to this thread and the service manual, fixed the 3.4V power supply failure. The failed MR20T1 is just a 3.4Volt rectifier/regulator module. It has no part in the overall regulation of the Power Supply.

    Used the mod described in the first post and all is well again.

    Anyone need help feel free to PM me.

    rgds Damon
    which supply lines of the MR20T1 do you actually cut?
    the 3.4V output lines are clear, but what about the input lines? in the image it looks as if the ones on the very right are cut, which would be the ground lines of the regulator. can someone confirm that?
    unfortunately there is no datasheet of the MR20T1 to cross-check...

    great instructions btw

  • #14
    Junior Member allspark's Avatar
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    Default Pictures seemed to go missing from my original post

    Just got a PM, asking for some pictures documenting my old modification guide. Was confused as there should be some linked.... As it turns out, that is no longer the case.
    I will look for the originals... Keep fingers crossed.

    uff found them...
    Re-posted images for original thread,

    Hopefully those will last longer...
    Last edited by allspark; 25-09-14 at 12:56 AM.

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    Default AllSpark, Many thanks for reposting the images.

    Quote Originally Posted by allspark View Post
    Just got a PM, asking for some pictures documenting my old modification guide. Was confused as there should be some linked.... As it turns out, that is no longer the case.
    I will look for the originals... Keep fingers crossed.

    uff found them...
    Re-posted images for original thread,

    Hopefully those will last longer...
    Allspark, Many thanks for reposting the images. I plan to do the modifications in a few days. Just waiting
    for the components to come by mail.
    If you were in my neighborhood, I would have probably bought you a beer. Cheers Amigo
    Last edited by ga973; 25-09-14 at 06:41 AM. Reason: typo

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    Smile

    Folks,

    I did the modifications as indicated by Allspark in the first posting.
    I used the following components
    1) AS2830-3.3 3.3v, 3Amp Sipex regulator
    2) 1N5822 Schottky diode

    I was able to get about 3.25 volts on pin2 of the connector and the projector was able to come on.
    However the lamp would shut off after about 30 seconds.

    I checked many postings including trying to replace the Q107 transistor but was not convinced to that being
    the problem.

    Eventually I got the MR20T1 to work momentarily and I measured 3.51v or 3.52 volts on pin 2 and with that the
    projector stayed on for a long time. So I figured as Allspark mentioned that the tolerances were very tight.
    The schematic specs mentions 3.4 volts.

    In the end I combined the parallel output of the MR20T1 and the modified 3.3 volts of the regulator and was able
    to get enough sense on the feedback for the projector to stay on for a long time.

    Instead of the 3.3 volt regulator I would recommend a 3.5 v regulator like LT912CM (3.5v, 3Amp).

    Anyway good luck and I encourage you'll to do the modifications.
    Last edited by ga973; 01-10-14 at 04:25 AM.

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    hey there, i will be attempting this asap... just a few questions, can someone possibly provide links to the parts i would require? also what is the Q107 transistor that was mentioned? im kind of a noob when it comes to this stuff but have lots of experience soldering etc... thank you for your time.

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    Can someone please repost the images?? I can't find a new / used power supply so will need to repair it.

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    Default Can someone please repost the images?

    I am also trying to repair an AE700 projector that makes a faint buzz sound and shuts off after 30 seconds and then flashes the red lamp light. Could someone please repost them or send me a private message so they can be emailed? Thanks!

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    Default

    Read allspark's post #14.

    Click on the word here in that post and you will be taken to the two images in question.

    The blue colour indicates a link.

  • The Following User Says Thank You to tristen For This Useful Post:

    FraggleRock (02-10-16)

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