Now when I power on, the power light goes red, then white, off for a second, then on white again. No picture or sound, and it does not look like any backlighting either. Any ideas on if p/s bd or main logic bd. I don't see any puffy CAPs on the P/S or main bd that might be bad. Thank you for your help, Carl
It could be either the main or power board, if you are comfortable doing it pull the back off and look for a pin on one of the connectors that says PSON...stands for power switch on and measure the voltage at that pin, if you have nothing the power supply board is bad, if you see a few volts on that pin push the power button on the TV and see if the voltage changes, say if its at 3 volts does it go to 5 volts or if its as 5 volts does it drop to a couple volts, if you see that happen then the main board is working and you need a power board, if there is no change its the main that is bad...Good luck!
Testimonial: "Larry, I don't find any PSON, but I found pin 1 on the main power cable to the main board says 24V PWR ON. When I turn on power I hear a click and this pin goes from 0v to 3.4v?"
Larry, I don't find any PSON, but I found pin 1 on the main power cable to the main board says 24V PWR ON. When I turn on power I hear a click and this pin goes from 0v to 3.4v?
Most sets have it labeled PSON but yours is one that is different, but you found the right pin to check and if its going to 3.4 volts then the main board is sending the signal to the power board to tell it to turn on power factor correction, the next question is the power board doing that?...on the power supply board there is a hot and cold section, look at the hot section and find a larger capacitor, one at 100 plus mfd at around 450 volt, hook your meter across that capacitor, when you turn the set on you should see about 160 volts and when the power button is pushed it should go to around 360, see if that happens, also be careful around that capacitor as it holds a charge way after the power is unhooked and from experience it doesn't feel very good to get across that...lol
Larry, I have 4 450v 47mf caps together? Before powering on I get 120v from +lead of 1 cap to ground, and across 1 cap or across +lead of first cap to -lead of 4th cap it seems to discharge to 0v. With power on, across 1 or all 4 caps it seems to spike high 400+v, and discharge. Here is a link to pic of my p/s bd. Power cord in at lower left, and 4 caps next to it. http://www.shopjimmy.com/lg-eay62169901-...
This is a low profile board so they used 4 lower uf caps all in parallel verses one larger one that would be a lot bigger in diameter. Are you measuring from the plus to minus of the capacitors to get the voltages you was talking about or to the metal frame?
I did both. before power on, from frame to +lead of cap = 120. From +lead to -lead of one cap and from +lead of 1st cap to -lead of 4th cap it is 0v. After power on from frame to +lead of 1st cap = 62v. From +lead to -lead of one cap and from +lead of 1st cap to -lead of 4th cap it spikes to a high voltage for a very short time, then discharges to 0v.
You need to be at the negative lead of the bridge rectifier or of the capacitors to get accurate readings..let me make sure I understand this...you don't get any voltage from - to + on any of the leads of those 4 capacitors?
Ok, I was assuming AC since these caps were near AC power cord. But it looks like they are DC. Before power on, 250v, after power on 397v across the 4 caps.
It should be DC, the rectifier changes it from AC to DC the capacitors filter the DC to get rid of the ripple, about 400 is good with the set on, it looks like you have an issue with the low side of the power supply, unless you know a fair amount about electronics that won't be something you will be able to fix yourself
If I have 24v, 3.5v going to the main board before power on, and have 24v, 3.5v and 12v going to the main board after power on and have 3.5v on PSON, I have a problem with the low side of the p/s board? The pins connecting the p/s to main bd show power expected / ground, and they have 3.5v and 24v before power on, and after power on also has 12v, and 3.5v on PSON. It seems to me like I have all voltages, and there is a problem with main board? So you think I should replace P/S bd, not system bd? There are links on the web that say no video, no sound, no backlight is caused by CPU getting hot/cold over and over, and causing cold solder joints on CPU chip? Thank you for your time, I have learned much about troubleshooting this TV.
If you have all your voltages on the power board then it should be working ok. Your not able to test for ripple on the DC lines unless you have a scope but if the capacitors look ok ripple should be ok, its really rare to have issues with the main causing the set to be dead like yours is as long as there is the power on voltage..I really don't know what to tell you, it is pointing to the main board and there really isn't any way to test any farther without changing out the boards.
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SOURCE: No Picture & No sound. Red LED, Green LED, Red LED.
If the power supply outputs are good! Then I would say the back light inverter is bad! If the screen stays black and does not come on.
SOURCE: TV green lite comes on for 2 seconds--goes back to
you posted the model number in reverse-----32pf double check-only thing i found so far -------replace c601 470/25v
someone else found a bad FET did u check them
do u have a pdf of this one
SOURCE: Red power light and buzzing sound with red lamp light.
If the lamp does not light at all, it is probably a bad lamp. The buzzing may be the ballast trying to start the lamp or a problem with the power supply. Check the lamp and see if the arc tube is broken. If its a new lamp, you should be under warranty. I have the manual if you want to go to me site at allprojectorlamps.com. Just send you email to me attention Bulb Guy
SOURCE: Sanyo DP50747 Replaced Power Supply still not working
this issue is related to either the y sustainer and z sustainer boards, checking the fuses on the y/b will giving you a good indication, if they are open(bad) then you'll have a easy fix, if not, i would try replacing the y board first.
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Ok, I was assuming AC, but that is not the case. Before power on 250 volts DC, after power on ~400v DC.
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