AKAI PDP4225m Statics/Flickering Screen

[j8manski]

So I have actually had this problem since the day I got the TV, but now it will not turn on. 2 yrs ago when I got this, the tv would flicker black screen/static screen for like 5 minutes on start up. then eventually the static screen would become less static and more of the video source(HDMI Xbox360) then eventually the flickers would become less and turn into a perfect picture. As for the audio I have no idea as my tv was always Volume 0 and have a surround system I use instead. But since then that 5 minutes has gotten longer and longer to the point where is was almost 2 hrs before my picture would show. Also in time, during those 2 hours, the tv would sometimes just turn off, where I had to just turn it back on. Or it would stop flickering and get stuck at a black screen where i would then have to HARD cycle the power as the button would not do anything to turn it off. I am now to the point where its been on for 5 hours and keeps getting stuck at black screen. I took it apart and replaced 2 CAPS on the PS(400V 270uf with 450V270uf), and now that removed it from getting stuck at that black screen. I checked the Va and Vs voltages, they are okay but fluctuate .5 volts +-(not sure if that is normal?, or because of the flickering?) I am determined to get this fixed so I can just hit the power button and get a picture instantly. I have a multimeter, and know how to use it, no oscilloscope sadly(although I miss having one from school). I hope some one can help? I can post pictures of anything. Thank you in advance.

EDIT: this is a Plasma TV, forgot to mention that lol And yes, I know its a cheapo brand, but it was only $75 2 years ago when I bought it used.

EDIT 2: So I just saw the diagnosing Plasma displays thread (I did do a search and that never came up). But to answer some troubleshooting ideas. I have no idea if I am getting sound or not, as I cant tell if I am on the correct input or not, or if my signal is even getting to the tv. I will also post pictures of the tv screen as soon as I can. As for my voltages, I forgot to mention, they seem like they are low. As in the Vs is usually up near 200V and mine are 80v? I also have a question on what is Vw=182.1 or Vx63.2?

[j8manski]

Re: AKAI PDP4225m Statics/Flickering Screen

So I was able to get some pictures and a video of the screen last night. I will try and get some more readings tonight of voltages and write them down. The first picture of the 2 large Caps are the 2 that i replaced. They looked to be swelling, but was weird because they were swelling from the outside and not the middle. You can see in the large picture of the PS that those are the replaced Caps in the middle. Also, why are there 2 pots to adjust the Vs and Va voltages? Yes they both adjust it as I messed with them to get the voltages set correctly after replacing the Caps. And as for that top one, I have no idea what that is for as It didn't effect either the Va or Vs voltage. I will get a picture of the secondary PS and an entire picture of the back of the TV with the layout of the boards soon. Thank you in advance for all the help.

http://youtu.be/MpHCVwjl9FI

[j8manski]

Re: AKAI PDP4225m Statics/Flickering Screen

Okay, so i keep doing some research every day and keep learning something new each time. I am leaning towards it being a Main board or Logic Board issue. Or it may even be the power supply, going to one of those boards. Like i said, my Va and Vs voltages seem good, but do fluctuate. I am assuming its because my screen is flickering a lot. But one voltage I cant seem to find is that Vw voltage. I cant seem to find any spot on the board that has a voltage of 182.1V, which seems weird because everywhere I look all the Vs voltages are up there, and my Vs voltage is 81.3? Another question is, I see a power cable that runs from the Sub Power Supply to the audio board? that is supposed to be 24V and measures more like 28V I think? Now I know that thats the audio board and shouldn't mess with the main board. But I see they are connected and maybe that 24v passes between them? I have measured the voltages going to the main board and from what I can remember they were 5v, that was a few nights ago so I dont remember the exact reading. And the logic board has a power connector, but its not labeled. I have looked through the service manual (mind you its not the best being AKAI), and I cant seem to find what the voltages are supposed to be going to it. I hope some one can help me with this, as we have NO tv now and im about to go crazy trying to watch my Netflix or tv shows on my laptop. Im attaching pictures of all the boards in the back (not the best as the lighting wasnt the best).

Again, thank you everyone in advance for the help. There is so much info on this forum. I am going to start looking to testing the voltage regulators.

Not quite an edit, but just remembered this. I tried using a heat gun on the back to see if that would speed up the warming process to show a picture.... with no luck. Just keeps flickering static. As I said before, It used to flicker and eventually show video.... but now nothing. Tried heating up each board individually, with no luck then tried to heat the all the boards with no luck. And I was very very careful not to overheat it. I made sure that I kept the heat gun moving at all time about 12" away to keep the super hot heat away.

[selldoor]

Re: AKAI PDP4225m Statics/Flickering Screen

Just a bit of encouragement really - I have never worked on a plasma - couldnt lift it for a start. Anyway you seem to be doing most of the right things though not sure about fiddling with the pots if you dont know what your doing.

Is it the same with all inputs and can you see any on screen menus.
Hopefully testing the VRs will find a rogue- good luck.
EDIT
Just one thing -in that 6th picture there is a blue cap - is the brown a leak
or just some marking ink?

[j8manski]

Re: AKAI PDP4225m Statics/Flickering Screen

Okay, So i looked into that Cap a little bit closer.... and you are correct, it is blown. When I first glanced over it, I thought it was just a yellow marking like some of the other caps have. I am going to see if the shack has one and Im going to try and replace it tonight. I inspected all the boards super close and didnt find anything else visually wrong. I also found 2 more pots, one on the main PSU and one on the Xbus. No idea what they do, did not touch either one. I also checked some voltages.

Main Board
5v pin = 5.1v on all 3
5v standy by measures 5v

Audio Board
24v pin =29.8v
9v pin = 9.38v

Main PSU
lower bluck/black cable (left to right)
3.15,3.15,3.15,1.15,1.68.04,3.29,.04,5.12

Right blue/black cable (top to bottom)
63.2,5.14,.01,.01,.01,81.3,81.3,81.3(When screen flickers those 81.3V varies -4V +0V)

So it looks like maybe the Audio Board or possibly the Secondary PSU which powers the audio board.

When i say audio board, I dont think its just audio as there are video inputs to it as well.

And you asked if any menus apear or if its just one input. That static/flickering is on all inputs i assume. it instantly does this on start up and pressing any button on the tv changes nothing. the only one that does is the power/standby button(unless that static/flickering gets stuck at just a black back light screen then i need to fully cycle power in back as the button in front does nothing)

[selldoor]

Re: AKAI PDP4225m Statics/Flickering Screen

I am going to see if the shack has one and Im going to try and replace it tonight.

I expect you have no idea how many of us cringe when we hear that.

I do not know where the cap is but Radioshack ore not renowned for selling
suitable caps. If it is on the power supply you should only use low esr caps.
Panasonic FC FM or FR or the nichicon , rubycon or ucc equivalents.

Also if one cap is gone then others in that area may be suspect and any others of the same brand and series in the set are suspect even without looking bad.

[newtothis]

Re: AKAI PDP4225m Statics/Flickering Screen

I am going to see if the shack has one and Im going to try and replace it tonight.

[j8manski]

Re: AKAI PDP4225m Statics/Flickering Screen

Okay. So. To make all of you happy, I did NOT replace any of the components from the Shack. For 2 reasons, as you are right, they seem VERY CHEAP, and also just dont have the right specs I am looking for. I also replaced a Cap on the Sub power supply that had a very slight bulge on the top. So now I am looking into the Voltage Regulators on the SUB Power supply, But I have no idea on how to tell the Specs of them. There are 3, 1 of which has a diode'ish symbol on it?? Im not sure what that means? I will attach a picture. Also as for the other ones, I measured both the input/output legs to the ground leg and on both legs I get the same voltage. I feel like I am doing something wrong.

Measurements for the heat sink with 2 regulators, using center pin as ground

Left regulator(or one that has symbol)
left leg - 5.1V
right leg - 5.1v

Right regulator
Left leg - 22.8
Right Leg - 22.8

Writing on right regulator.... may be off on some of it as it is difficult to read as is stuffed right behind other components that are in the way.

TPR 1020 CFP
6k1RF VU
CNN 544

Then the regulator that is on the heatsink that is by itself
Left leg - 62.8v
Right Leg - 314v

Then there are 2 4 pin regulators I think? Im not sure what they are, but i think they are a regulator? Was wondering if those can go bad? If so, how can i measure them?

COSMO
1010
817
F48
B

Thank you for your help

[selldoor]

Re: AKAI PDP4225m Statics/Flickering Screen

Ok I dont think any of these are voltage regulators they look to be diodes hopefully
you will not have damaged them. What are the board descriptions may be D???

Pic 1 for example is
https://cdn.badcaps-static.com/pdfs/...d01a5d055f.pdf

[j8manski]

Re: AKAI PDP4225m Statics/Flickering Screen

The only thing I can see are the 2 components on the heatsink.... not the one that is on its own, but the 2 right next to eachother just say D7 and D8. Thats from looking at pictures on my computer I have. I cant get to the board at the moment so I dont know what it says below the other component that is on the heatsink itself.

[selldoor]

Re: AKAI PDP4225m Statics/Flickering Screen

ok so you need to test them as diodes

[j8manski]

Re: AKAI PDP4225m Statics/Flickering Screen

Okay, I will do that tonight if I have the time. Im assuming that its basically 2 diodes sharing the center pin? So i would test it from the center to left and center to right? And what exactly am I testing? Its been a long time since I tested diodes, and my Multi-meter has a diode setting, but when I use it it gives me a reading. What is that reading? I played with it the other night on a few other diodes on the board and it didnt beep, it would either give me 0 if I tested it in one direction and a reading in the other. The only time i could get it to beep it by touching the probes directly together or over a resistor, but not on any of the diodes. When I was testing that, it was on the single diodes, not the ones in question on the heat sinks.

[selldoor]

Re: AKAI PDP4225m Statics/Flickering Screen

There are many tests shown in this guide by retiredcaps= start at post 19

https://www.badcaps.net/forum/showthread.php?t=10419

The one I posted the link for is a double diode so your test is correct
you should check the datasheets for the others to check the configuration