Samsung 933HD not staying on help

[mots]

HI,

I have a samsung 933HD which is being a pain it sometimes turns on and the blue light displays but no responce when pressing the power button but other times it turns on but off after a few seconds and then other times it works fine untill I put it on stand by again

I have replaced all the capacitors on it apart from the large 450v 100uf

I was going to replace all the resistors but hit a snag - there is one with only 2 bands on either side a black and a yellow and on the board next to it it says "F201 F4.0AL 124v" any idea what that is and where i can purchase one from?

Any idea what could be the problem? Also how can I test the components? - I have a multimeter.
The power board it self is a PWI2204ST rev 1.0 - I was considering buying a replacement for about £50 / $79.32 and thought I could prob buy a new tv for a little more.

Any help on getting this working would be greatly appreciated.

[retiredcaps]

Re: Samsung 933HD not staying on help

I have replaced all the capacitors on it apart from the large 450v 100uf

I was going to replace all the resistors but hit a snag -

1) What brand and series capacitors did you use for the replacements?

2) Why do you need to replace all the resistors?

3) Post clear focused pictures AFTER reading

https://www.badcaps.net/forum/showthread.php?t=1868

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

For best picture quality and clarity take your boards to a window on a sunny day, turn flash off, and use macro mode. Take a top down view of all your boards (front and back). Make sure the photo is legible so that we can read the PCB printing clearly. A shutter speed of 1/125 or faster will produce nice clear focused pictures. Try to get a photo that is 2000x2000 resolution or as close as possible.

Here is an example of the pictures we want.

https://www.badcaps.net/forum/showpo...94&postcount=1

[mots]

Re: Samsung 933HD not staying on help

the capacitors i used were;
> suntan cd287 LESR -40+105'C = 470uf 25v
> suntan cd287 LESR -40+105'C = 1000uf 16v
> SD CD263 105'C = 47UF 35V
> EB [M] 105'C =10UF 50V
> KZE 105'C = 330UF 25V

Im guessing these are bad cheap caps

well i dont need to replace all the resistors but i thought that would be a good thing to do after doing the capacitors and hopefully will get it working but i cand fins the resistors with only a yellow and a black band on it.

I will take some pictures of the board tomorrow, please dont mind my handywork

[PlainBill]

Re: Samsung 933HD not staying on help

the capacitors i used were;
> suntan cd287 LESR -40+105'C = 470uf 25v
> suntan cd287 LESR -40+105'C = 1000uf 16v
> SD CD263 105'C = 47UF 35V
> EB [M] 105'C =10UF 50V
> KZE 105'C = 330UF 25V

Im guessing these are bad cheap caps

well i dont need to replace all the resistors but i thought that would be a good thing to do after doing the capacitors and hopefully will get it working but i cand fins the resistors with only a yellow and a black band on it.

I will take some pictures of the board tomorrow, please dont mind my handywork

That's because it's not a resistor - it's a fuse.

PlainBill

[mots]

Re: Samsung 933HD not staying on help

That's because it's not a resistor - it's a fuse.

PlainBill

I thought that as it has f201 and not r*** written on the board - where can i get this fuse from? what is it called?

-Thanks

[PlainBill]

Re: Samsung 933HD not staying on help

I thought that as it has f201 and not r*** written on the board - where can i get this fuse from? what is it called?

-Thanks

It's called a 'Fuse'. Now, I'm going out on a limb here, but it sounds like it could be a 'Picofuse'. You see, I'm a certified electronics genius (my brother-in-law says certifiable, but you know how in-laws are), but without a clear look at (or picture of - hint) the part in question, I have no way of knowing what it looks like.

More to the point, why are you replacing parts without determining if they are defective? I've known 'techs' who 'shotgunned' by replacing half a dozen components at the same time, but what you are doing is more like a hand grenade.

PlainBill

[mots]

Re: Samsung 933HD not staying on help

hi,

Yes i hoped i would hit the problem by firstly replacing the caps then the resistors as they seem to be the main cause to most problems but main reason is i dont know how to test them.

I have attached the pictures.

Thankyou for your help

[mots]

Re: Samsung 933HD not staying on help

how would i go about testing these components? using a multimeter?

[PlainBill]

Re: Samsung 933HD not staying on help

Let me state this clearly: You are using the wrong approach!!!

If you took your car to a mechanic because the acceleration was sluggish and the handling was sloppy would you be happy if he started by making sure every bolt was torqued correctly? Would you be appreciative of his thoroughness if he then wanted to check every screw in the car?

Or would you be a little more confident if he started by checking the tire pressure, checking for play in the steering linkage, looking at the air filter, and checking things like shocks and alignment?

There are a few basic voltage tests that can help isolate the problem area. I hesitate to suggest them because I question if you know enough to avoid electrocuting yourself!!!

PlainBill

[Dgtech]

Re: Samsung 933HD not staying on help

The two components , that have been pulled off of the board already, can be tested by using the ohms resistance scale. Measure these components and record what you see. If that one is a fuse, it will either show one of two things: zero ohms, if good, or infinite if bad (blown)

For the record, resistors rarely need replacing if they have not burned. If I were you, I'd put it back together and start over with a better method like Plainbill suggests. Peeking and Poking is the wrong way.

[mots]

Re: Samsung 933HD not staying on help

ok i totally understand what you are saying Plainbill, I am going to put everything back together again tomorrow and start again and leard how to test each component to try and idenntify anynthing that needs replacing.

lesson learnt wont be doing that again

[Dgtech]

Re: Samsung 933HD not staying on help

Instead of measuring or checking each component, how about a verifying a few voltages at a couple of points that we can point out to you. This will tell us exactly where you should be looking for the problem and will save you days less than your current technique.

[mots]

Re: Samsung 933HD not staying on help

Instead of measuring or checking each component, how about a verifying a few voltages at a couple of points that we can point out to you. This will tell us exactly where you should be looking for the problem and will save you days less than your current technique.

yes of course any help or guidance you can provide will be much appreciated.

[Dgtech]

Re: Samsung 933HD not staying on help

With the unit on, what are the voltages that you see on the connector at the bottom left hand side of the first picture. This connector has all black wires and one red wire. When measuring this, usually one of the pins will say ground or GND. Use this pin for your negative lead of your meter and then probe the rest of the pins. DO NOT use the ground on the HOT side of this board.

[retiredcaps]

Re: Samsung 933HD not staying on help

And just to be clear, you are measuring for DC V. If you have a manual multimeter, set it to 20V DC.

We had one person a few weeks ago insisting that the measurements at the connector were in mV AC.

[mots]

Re: Samsung 933HD not staying on help

With the unit on, what are the voltages that you see on the connector at the bottom left hand side of the first picture. This connector has all black wires and one red wire. When measuring this, usually one of the pins will say ground or GND. Use this pin for your negative lead of your meter and then probe the rest of the pins. DO NOT use the ground on the HOT side of this board.

Ok i have just put everything back on and done a quick test and I have listed what each cable is and what the reading was;

1) B-Dim = 0.00
2) +15v = 14.85
3) GND
4) GND
5) GND
6) +5.1v = 5.18
6) +5.1v = 5.18
7) A-Dim = 0.00
8) On/Off = -0.01

Has that narrowed things down? I am not sure if that will help as the lcd can work sometimes then others wont so might be working fine when i tested it but fail again after.
I'm going to test it again in about 5 min to see if anything changes.

[Dgtech]

Re: Samsung 933HD not staying on help

HI,

I have a samsung 933HD which is being a pain it sometimes turns on and the blue light displays but no responce when pressing the power button but other times it turns on but off after a few seconds and then other times it works fine untill I put it on stand by again.

We have a saying at work - " it's not broke enough". I hate troubleshooting intermittent failures. If it were dead, GREAT. If it works fine half the time and fails once in a while, crap. You're gonna have to sit there and monitor those voltages during workiing times as well as not working times. If you have it on a stand standing up, this will be best so you can see the screen when it's on and when it doesnt come on. This isnt going to be fun but it's what you have to do.
Also, the on/off voltage should change whenever you press the power button.
Take your time and record all that you see. You will find the problem sooner or later.

[mots]

Re: Samsung 933HD not staying on help

We have a saying at work - " it's not broke enough". I hate troubleshooting intermittent failures. If it were dead, GREAT. If it works fine half the time and fails once in a while, crap. You're gonna have to sit there and monitor those voltages during workiing times as well as not working times. If you have it on a stand standing up, this will be best so you can see the screen when it's on and when it doesnt come on. This isnt going to be fun but it's what you have to do.
Also, the on/off voltage should change whenever you press the power button.
Take your time and record all that you see. You will find the problem sooner or later.

ok thanks I'll try and keep recording the results to see if there is any change - I will try connecting it all up to see if there is any change when the lcd stays playing up again but not sure how to do it wile everything is connected as the board will be flipped the other way round so not very accessible but will give it a try now tho

[alexanna]

Re: Samsung 933HD not staying on help

The problem you're having with the power LED being on but no response when you push the button, sounds like a problem I have noticed when one or more of the voltage regulators are starting to fail.
I f you could post a picture of the logic board

[mots]

Re: Samsung 933HD not staying on help

The problem you're having with the power LED being on but no response when you push the button, sounds like a problem I have noticed when one or more of the voltage regulators are starting to fail.
I f you could post a picture of the logic board

The readings changed when i plugged everything in and turned it on, they are as follows;

1) B-Dim = 1.50
2) +15v = 15.44
3) GND
4) GND
5) GND
6) +5.1v = 5.18
6) +5.1v = 5.18
7) A-Dim = 0.70
8) On/Off = 5.02


I have attached some pictures of the logic board, is there any way I can test the voltage regulators?