Proscan 55LC55S240v69

[mr.urie]

I have a Proscan 55LC55S240v69. I have replaced all the caps on the power supply board. It will light up the little red light on the power supply board and click, flash once on the screen, click again and power off. It will then stay off unless I unplug the cord and plug it back in. Then the process can start again. Any suggestions?

Here is a link to an image of my board. http://assets.shopjimmy.com/media/ca...j/sj123882.jpg

Thanks,

[70JUDGE]

Re: Proscan 55LC55S240v69

Here is a link to the same TV,with a similar problem.There must be a common problem with Proscan power supplies.What it is,I haven't figured out yet.Here is a link to the TV I had.I hope this helps.Thank You very much!

Tyler

http://www.ebay.com/itm/ws/eBayISAPI...OIBUAA:US:1120

https://www.badcaps.net/forum/showthread.php?t=13753

[PlainBill]

Re: Proscan 55LC55S240v69

I have a Proscan 55LC55S240v69. I have replaced all the caps on the power supply board. It will light up the little red light on the power supply board and click, flash once on the screen, click again and power off. It will then stay off unless I unplug the cord and plug it back in. Then the process can start again. Any suggestions?

Here is a link to an image of my board. http://assets.shopjimmy.com/media/ca...j/sj123882.jpg

Thanks,

Linking to a stock image of your board is a little like asking your doctor to use the X-rays of your brother. It doesn't work that way.

PlainBill

[mr.urie]

Re: Proscan 55LC55S240v69

I'll have my brother post some pics of my board then. I thought maybe someone could point me to an area to look. I will try to post images of my board when I get on my laptop.

Thanks for the help.

[gsmy]

Re: Proscan 55LC55S240v69

I have the same tv with the same problem as the original poster. I have replaced caps on the power supply that where bad and replaced most of the rest with good quality ones. My output voltages (5v, 12v, and 24v) are good, but it has 2) 14v outputs that are at 16v on stand buy and climb to 20v when it tries to turn on. I also replaced the main board but it didnt change anything. Should I start a new post with my symptoms and what I have found? Thanks

[selldoor]

Re: Proscan 55LC55S240v69

Welcome to the forum-

There is no need to start another thread however restate what the problem was, (we dont like having to look back to find out) what you have done/tried and the result

We can help a lot more if you please post good clear pictures of the whole chassis, and then pictures of each board, front and back and close up of connectors, (max resolution 2000x2000 and 2MB) using the manage attachments button, which is found by clicking "go advanced" under quick reply.

Please do not post inline and offsite as they slow down the loading of pages.

Examples of what is needed
https://www.badcaps.net/forum/attach...1&d=1290283049

https://www.badcaps.net/forum/attach...7&d=1280167246

It will be useful if you can say a bit about yourself - skills tools etc.

[gsmy]

Re: Proscan 55LC55S240v69

Thanks for the welcome. I will try to give a description of the problem and what I have done so far. The TV is one of three that came from a commercial application and was used as a monitor that stayed on about 12 hours a day 7 days a week for about a year. One tv is still in use, the other died and they had it repaired which was the power supply. I was given the 3rd one as they did not want to spend any money on it.

When I got the tv I pulled the back off and looked things over and plugged it in. I could hear a relay click on the power supply but that was it. The red light on the front of the tv came on and went off and that was it. So I did some research and everything pointed to a power supply problem. It seems this model has a lot of power supply issues. I took the power supply out and looked it over and found one high voltage capacitor next to the large transformer that was burned. I ordered it as well as the other capacitors on the board and replaced them. I reinstalled it and checked all the connections and tried it again.

This is the current condition. I plug it in (red light on front of tv comes on) and the power supply starts and I can hear different relays click and all the voltages come up at the connectors and it goes into a standby mode and most of the voltages go off except for the 5v ones. The red light on the front of the tv turns off but the blue light does not come on. Next I try to turn it on with either the remote or the switch on the front of the tv. Relays on the power supply click and I hear a buzzing sound for a few seconds and see the back of the screen turn white (grey on the front) and the power supply clicks off and the red led on the power supply comes on and stays on. Also the red light on the front of the tv comes on, flashes 3 times, goes off and back on. At this point you can not turn the tv off, you have to unplug it.

I checked all the output voltages at the different stages and they all match whats printed on the board except for the two 14v outputs. These read 16v at standby and climb up to 20v when its trying to turn on. I have not been able to find a schematic to be able to trace it back to determine what could be causing the voltage to be high. I also tried another main board as proscan tech service suggested but the only difference it made was that it tried to start a few times instead of once.

I am not sure which way to go next. I dont know how to test to see if the screen is bad or the other boards. I dont have access to another power supply and dont want to buy boards if they are not bad. I have a DVOM and have a friend with access to a scope and other diagnostic equipment. I am looking for some guidance as to a systematic procedure to check it out. I dont want to spend $300 on boards to figure out the lcd screen is bad.

[gsmy]

Re: Proscan 55LC55S240v69

I am working on getting some close up pictures of the power supply board front and back and will post those soon.

Also does the light flashing on the front of the tv 3 times corespond to some fault code? The tv is the same as a RCA 55LA55RS if that helps.

[gsmy]

Re: Proscan 55LC55S240v69

I havent been able to get a picture of my board loaded yet but came across this picture online and its a good image.

I checked the power supply output voltages again to confirm. All of the voltages (3,5,12 & 24) are good. There are 2 14v pins that read 16-17v at standby and climb to 20v when it tries to turn on. I figured out that these are for the audio part of the main board. I removed the 2 pins from the connector and tried again and got the same readings. so its definately happening on the ps board.

I found that the buzzing noise is coming from the large transformer when it tries to start and if I disconnect the bulb connectors it goes away.

I really think its a power supply issue. It never gets past trying to light the lamps, no sound, no picture for the few seconds the lamps come on.

I have gone over the board the best I can with my meter checking everything I could with a meter and cant find anything. Could the transformer be faulty? I did replace the high voltage cap on the left next to it because it was burned. Would this be like a flyback transformer.

I have read numerous posts about the power supplies on these tv's but no one has indicated what fails on them. I am at the point of ordering a new ps board but worry that it could have some other problem like the screen or other board. Help!

[awyatt2]

Re: Proscan 55LC55S240v69

plain bill said it was like linking to images of your brother to tell what was wrong with you. we need to se your board not someone else's board. if the board in the pic works then we cannot see what is wrong with yours, you need to use sight to see if anything is wrong, touch or feel tpo see if anything is overheating and smell if anything is roasting. the buzzing could indicate a shorted diode or startup cap. alwaYS START BY CHECKING VOLTAGES. they should be marked on the ps board if you have good voltage then you know the problem is elsewhere.

[gsmy]

Re: Proscan 55LC55S240v69

I understand about the pictures and working on getting some posted of mine but wanted to include something to just show the board and its components. However if you noticed I am not the original poster and have tested all the voltages and indicated what I found along with its problems. I have gone over the board with my dvom checking different components. Nothing seems to be overheating, no smells, and no burned componenets.

[gsmy]

Re: Proscan 55LC55S240v69

Here are some pics. I will have to come up with some better lighting for the close ups.

Again here are the symptoms. Plug it in, hear relays click and red light on front comes on. Turn on tv with either rc or pwr button, hear relays click, can see back of screen light up white for couple of seconds, large transformer on ps buzzes and it turns off. Red light on front of tv will flash 3 times and red led on ps will be on. Cant turn it off, have to unplug it.

Replaced the high voltage capacitor next to the big transformer (burned) and replaced all the other capacitors on the dc side. All voltages are good except the 2-14v ones that read high at standby (16v) and climb to 20v when it tries to turn on with or without the load connected. Believe these are for the audio. Also swapped the main board with another that is supposed to be good, only difference is that it will try to turn on 4 more times before it quits. Figured that might be a firmware change? All the voltages are steady when it tries to turn on, none drop more than a .5v at most.

[gsmy]

Re: Proscan 55LC55S240v69

I will be able to get better pictures tommorow if it will help. I cant find any schematics or service info for this tv. Does anyone have any suggestions on which way to go with it. The symptoms seem common for this model as I have found searching the web but no definite answers for the problem. Any help will be greatly appreciated.

[tom66]

Re: Proscan 55LC55S240v69

Can you check those three, white, bent over resistors for low resistance? (should be nearly zero.)

[gsmy]

Re: Proscan 55LC55S240v69

They measure 0.2 seems good.

Is there any where to find a schematic for the power supply or service manual?

Is there anyway to tell what / if the three flashing light is a code for?

[gsmy]

Re: Proscan 55LC55S240v69

Is there any way to test the other boards to rule them out? I am considering ordering a new power supply since I cant get a schematic.

[gsmy]

Re: Proscan 55LC55S240v69

What about a problem with the back lighting or inverters? When I unplug one side of the lamps the transformer gets quieter. If I unplug both sides it doesnt make any nosise. Obvioulsy it still does not work. I have read on here about backlighting issues on other tvs that overload the psu and cause it to shut down. Could this be a possibilty? It does light the lamps for a few seconds before it shuts down. Is there anybody that has any experiance with this tv or access to service information for it?

[gsmy]

Re: Proscan 55LC55S240v69

I was able to borrow another working power supply from one of the other tvs and swapped it into my tv and everything works! So that rules out any other problems with the other boards or screen.

When the tv turns on with the new ps it is quiet and does the exact same sequence and light flash as the old ps, except it works. I went thru and checked all the voltages and they are within 3-5% between the two power supplies. The symptoms with the old ps are: when its trying to turn on and the backlight is trying to come on, the big transformer in the middle makes a loud buzzing sound for the few seconds while the backlights are on and then it shuts off and the tv is locked. You cant do anything with the rc or buttons only unplugging the power cord works.

With the new ps, it follows the same sequence except the backlight stays on with no noise and then the screen and receiver start and everything including the rc, inputs, menu, etc works.

The borrowed power suplly was replaced at some point and it looks like it may have been rebuilt. On my board all the transformers are made by the same company but on the borrowed board it looks like the big transformer may have been replaced because its a different brand with different numbers as well. Do you think my transformer could be bad and is there a way to test it? I only have the borrowed ps for a couple of days so if there is anything I need to compare it against I need to do it quick. Any other help would be greatly appreciated. Thanks

[awyatt2]

Re: Proscan 55LC55S240v69

check the diodes for shorts and the smaller caps for high esr. had several recently that have had bad caps and shorted diodes on the startup side of the ps. the caps that i have found of recent were very small and showed no signs of failure just had high esr.

[gsmy]

Re: Proscan 55LC55S240v69

I began by recapping the board on the low voltage supply and replacing a high voltage cap next to the big transformer that was burned. I have used a ESR meter and checked all the other caps even pulling some out that seemed suspect, but found nothing. I used a meter and checked the rest of the components and found nothing else as well. The crazy thing is that all the voltages are present and match the ratings on the board. But something happens when the back light starts and causes the ps to shut down. Its like the ps is 95% working but cant get past the back lights starting.