Samsung Syncmaster 2233RZ No power

[BGAmodz]

Here are the readings I got from the IC101 pins:

VCC to GND : 8V to 14V
VFB to VCC : (-4.5V -to -8.8V)
VFB to GND : 10V - 12V
VSTR to GND : 40V to 130V

i think vcc should be a fixed voltage , and according to the datasheet it should have a fixed 20 volts .

 

[accesspoint2007]

How did you test them?.

I just did a simple test using a VOM.

 

[Nigel Goodwin]

I just did a simple test using a VOM.

You can't test capacitors in that way, apart from just seeing if they are S/C or not - which is a pretty rare failure mode.

To test electrolytic's you need an ESR meter, as the failure mode is almost always high ESR (and is the most common electronic failure over the last 10-15 years - by an absolute mile!!).

Looking at the original picture the board is PSU and Inverter, and Samsung have had pretty large failures on their inverter transformers - it's possible that the PSU section is shutting down because of inverter problems?.

 

[accesspoint2007]

Hi Nigel Goodwin,

Are you referring to the yellow transformer (T101)? Do you have an idea where can I buy that part or would it be better to replace the power board instead? Does anybody know where I buy one?

 

[rumpfy]

The clicking noise sounds to me like the IC is trying to start up. It does this by pulsing the start pin. When the device starts it gets its supply from the output side through the rectifier.
These things often fail to start because of an excessive load on the secondary side. I would try to disconnect all the main secondary loads except for the feedback/optocoupler.
I find this stuff almost impossible to diagnose unless a CRO is used. You might get lucky. I would doubt the transformer is faulty, but it may be. This could be checked with a a CRO if you had one.

 

[Nigel Goodwin]

Hi Nigel Goodwin,

Are you referring to the yellow transformer (T101)? Do you have an idea where can I buy that part or would it be better to replace the power board instead? Does anybody know where I buy one?

No, T301 at the top - if you don't know the difference between an inverter transformer and the mains transformer perhaps you shouldn't be trying to repair things?.

Samsung's service policy is to replace the entire board, and they generally don't supply either circuits or spare parts for individual PCB's.

 

[Zerotolerance]

I might have to disagree with you Nigel. No offense meant, but speaking from personal experience and by making subjective inferences; I have been able to repair PSU's of various sorts, without really knowing what was what (If I may use that phrase). Of course, I did this when I very first got started in electronics with very basic knowledge.

And yes, Samsung's policy is to replace the whole PCB with a new one.

 

[accesspoint2007]

Hey guys! Thanks for all your inputs and suggestions.

>>> Nigel Goodwin Said:
>>> No, T301 at the top - if you don't know the difference between an inverter transformer and the mains transformer perhaps you shouldn't be trying to repair things?.

Special thanks to Nigel for his encouraging words!!!! I believe this forum is made to help each other and provide information, education and suggestions to better enhance our knowledge and skills. If your son asked you which one is Tuna and which one is mackerel? Would you tell him 'you shouldn't be eating fish if you don't know the difference between tuna and mackerel?

I may not be as genius or as intelligent as Nigel but I already fixed the problem. My monitor is alive again!!!!

Many thanks..[/

 

[BGAmodz]

I may not be as genius or as intelligent as Nigel but I already fixed the problem. My monitor is alive again!!!!

Many thanks..[/

Hi access , can you share how you fixed the problem ? am really curious !! , my guess is a fault before the Power IC ?

 

[accesspoint2007]

Hi access , can you share how you fixed the problem ? am really curious !! , my guess is a fault before the Power IC ?

I replaced all suspected components. Changed all electrolytic caps and IC101 (which I already ordered online prior to posting this forum). I also replaced F301 as it gave me a very high resistance reading. I just replaced it with a regular type glass fuse with same rating (temporarily) as I could not find an exact match from the electronic shop.

Thanks!

 

[BGAmodz]

I replaced all suspected components. Changed all electrolytic caps and IC101 (which I already ordered online prior to posting this forum). I also replaced F301 as it gave me a very high resistance reading. I just replaced it with a regular type glass fuse with same rating (temporarily) as I could not find an exact match from the electronic shop.

Thanks!

Happy to hear that . even though probably 70 % of components you've changed were working just fine .

 

[KeepItSimpleStupid]

Well, the fuse and it's ability to check good in circuit was the first thing I suggested, The caps best checked with ESR and probebly better off if changed together. That leads to the question whether IC101 died to protect the fuse and it probably didn't.

Congrats!

So, I do have to tell you a story which happened twice in my life, The fuse (3AG style) checked OK with an ohmmeter out of circuit, but it would open under load. Checking the voltage across the fuse in circuit found it.

 

[accesspoint2007]

Happy to hear that . even though probably 70 % of components you've changed were working just fine .

You're right BGAmodz. LOL... Just to lessen the headache and simplify troubleshooting. It works most of the time. It's like when you take your car to a shop and the mechanic points to all the parts that you may need to replace although not necessary.

 

[accesspoint2007]

Well, the fuse and it's ability to check good in circuit was the first thing I suggested, The caps best checked with ESR and probebly better off if changed together. That leads to the question whether IC101 died to protect the fuse and it probably didn't.

Congrats!

So, I do have to tell you a story which happened twice in my life, The fuse (3AG style) checked OK with an ohmmeter out of circuit, but it would open under load. Checking the voltage across the fuse in circuit found it.

Thanks KeepItSimpleStupid! I really do appreciate your inputs and suggestions.

 

[Zerotolerance]

Just by looking at IC101 you can tell that it is discolored, which is a sign that it overheated and blew (without actually physically blowing). At least it appears to look discolored to me.

 

[BGAmodz]

That leads to the question whether IC101 died to protect the fuse and it probably didn't.

He said that the ICs VCC was having 8v to 14 v , and the datasheet says it should have 20 v , i doubt the IC was bad , its something before that i guess ?