Samsung 930b LCD cold start problem (inverter?)

[tiloup]

Re: Samsung 930b LCD cold start problem (inverter?)

The simplest is a loose cable from the logic card to the panel itself

It was the simplest ..... I didn't connect this cable....shame on me, going to hide in the forest....
Thanks a lot for your help !

[PlainBill]

Re: Samsung 930b LCD cold start problem (inverter?)

It was the simplest ..... I didn't connect this cable....shame on me, going to hide in the forest....
Thanks a lot for your help !

If you see a gingerbread house, 'Watch out!!!'

PlainBill

[jbradley]

Re: Samsung 930b LCD cold start problem (inverter?)

I would like to thank you guy's for this forum! I was able to resurrect a monitor for a neighbor because of this thread! PlainBill, what can I say, thank you!

F301 was my problem also after a full recap. I looked at the entire board as did a coworker and both of us looked right over this fuse. We repair electronics for a living and can't believe we both overlooked this.

[PlainBill]

Re: Samsung 930b LCD cold start problem (inverter?)

I would like to thank you guy's for this forum! I was able to resurrect a monitor for a neighbor because of this thread! PlainBill, what can I say, thank you!

F301 was my problem also after a full recap. I looked at the entire board as did a coworker and both of us looked right over this fuse. We repair electronics for a living and can't believe we both overlooked this.

The hardest faults to catch are the ones you KNOW can't be the cause of the problem. Those @#%#@%! SMT fuses are #2.

PlainBill

[EGuevarae]

Re: Samsung 930b LCD cold start problem (inverter?)

Those @#%#@%! SMT fuses are #2.

PlainBill

[demens]

Re: Samsung 930b LCD cold start problem (inverter?)

Hey guys, thanks for all the great info, i'm confident i can now fix my monitor. My problem looks to be much like the OPs, except that after about 30 min. after turning it on, the monitor works perfectly fine.

I have a complete newbie question about ESR.

My board looked a bit different then the OP but the same Samxon GF 820uf cap is dying (just 1 visually, i have 3 on my board). The problem is that i'm having trouble finding $a replacement. There are plenty of of places online, but thats gonna take $10-$15 from the min. orders or shipping cost. Am i just being cheap, cause i dont wanna pay that much for 1 (or 3) caps that shouldn't cost more then $2. I ordered a free sample of the KY that the OP suggested, not sure if they will actually send it to me, so i went to a local electronics shop and bought one. It took hours for me just to find a store that sells them other then Radio Shack (who were out of the ones i needed). And the guys at the stored seemed pretty clueless about capacitor brands or what ESR is.

So my question is, what can possibly happen if i replace that 1 bad cap with the generic one i got at the store (1000uF, 25V)? Ratings seem fine aside for the ESR which i dont know but is probably not low.

[retiredcaps]

Re: Samsung 930b LCD cold start problem (inverter?)

My board looked a bit different then the OP but the same Samxon GF 820uf cap is dying (just 1 visually, i have 3 on my board). The problem is that i'm having trouble finding $a replacement. There are plenty of of places online, but thats gonna take $10-$15 from the min. orders or shipping cost.

If you live in the USA, digikey.com has no minimum order and shipping costs under $3 USD.

Am i just being cheap, cause i dont wanna pay that much for 1 (or 3) caps that shouldn't cost more then $2. I ordered a free sample of the KY that the OP suggested, not sure if they will actually send it to me, so i went to a local electronics shop and bought one. It took hours for me just to find a store that sells them other then Radio Shack (who were out of the ones i needed). And the guys at the stored seemed pretty clueless about capacitor brands or what ESR is.

Under $3 USD for shipping and handling is preferable to driving hours and used gas.

So my question is, what can possibly happen if i replace that 1 bad cap with the generic one i got at the store (1000uF, 25V)? Ratings seem fine aside for the ESR which i dont know but is probably not low.

It will likely work, but you may be taking apart the monitor in a couple of months. Members hear suggest you replace ALL the caps because this monitor is 5 years old probably. In addition it is a 19 inch monitor which means you are likely to keep it for a bit longer.

Assuming this cap is the right height and diameter (Panasonic FM are low ESR),

http://search.digikey.com/scripts/Dk...name=P12391-ND

they are 0.62 cents each. So if you get 3 + s/h, it should be around $5 USD.

[lucky13]

Re: Samsung 930b LCD cold start problem (inverter?)

demens,

Welcome. Please update your location profile with at least country name.

[demens]

Re: Samsung 930b LCD cold start problem (inverter?)

http://search.digikey.com/scripts/Dk...name=P12391-ND

they are 0.62 cents each. So if you get 3 + s/h, it should be around $5 USD.

Ahhh, yes. I just saw the 1st option for UPS ground being $8 and thought it was the cheapest one. Did not see the $3 option. Thats much better, thanks. Hopefully this goes smooth, i will replace all 3 samxon (but not all the caps on the board).

[PlainBill]

Re: Samsung 930b LCD cold start problem (inverter?)

Ahhh, yes. I just saw the 1st option for UPS ground being $8 and thought it was the cheapest one. Did not see the $3 option. Thats much better, thanks. Hopefully this goes smooth, i will replace all 3 samxon (but not all the caps on the board).

There is difference between thrifty, being cheap, and being foolish. The odds are more caps are bad than just the obvious ones. A complete set of caps will cost less than $10 delivered. Are you looking forward to opening the monitor again in 6 months to replace more caps?

I tried to save money on a Gateway monitor. I didn't replace a couple of caps because 'they looked good'. It wasn't until I found this site that I learned that the $.28 cap I didn't replace was the reason the monitor still wasn't working.

PlainBill

[demens]

Re: Samsung 930b LCD cold start problem (inverter?)

There is difference between thrifty, being cheap, and being foolish. The odds are more caps are bad than just the obvious ones. A complete set of caps will cost less than $10 delivered. Are you looking forward to opening the monitor again in 6 months to replace more caps?

I tried to save money on a Gateway monitor. I didn't replace a couple of caps because 'they looked good'. It wasn't until I found this site that I learned that the $.28 cap I didn't replace was the reason the monitor still wasn't working.

PlainBill

So you would recommend replacing every single cap on the board? Everyone seems to say that the Samxon GF are the faulty ones, i intend to replace all 3 (although only 1 looks bad), but you're saying that i should replace the others as well?

Btw, couldn't wait, tried to replace that 1 clearly bad cap with the generic cap i got from the Electronics store. Screen was completely black with no noise, thought i killed it, but after 10 min. or so it started making the hissing sound again (a lighter one) and now about 40 min. later is still in the process of turning on. Lesson learned i guess.

[retiredcaps]

Re: Samsung 930b LCD cold start problem (inverter?)

(although only 1 looks bad)

You will learn that caps do not have to be bloated to be bad.

Caps die from age, heat, and dry out.

A 1000uF 16V cap can be bad if it measures 300uF (out of tolerance). A 100uF 25V cap be bad if it reads 10 ohm on a ESR meter (it should read 0.2 or somewhere around that area). In both cases above, both caps can have a perfect flat top.

Since all the electrolytic caps were probably installed at the factory at the same time, they have aged similarly. Of course some caps that are closer to heat components than others and may go bad more quickly, but ALL caps will eventually go bad.

[momaka]

Re: Samsung 930b LCD cold start problem (inverter?)

So you would recommend replacing every single cap on the board?

Well, you don't need to replace the big 400v cap since that one rarely fails. The really small ones (10uF, 22uF, and 47uF @ 50v) are also optional - but they are cheap, and usually there aren't many of them on the PSU board, so just replace them anyways (for these, make sure the new ones have the exact same voltage and capacitance rating as the original ones, though).

[balenu]

Re: Samsung 930b LCD cold start problem (inverter?)

Hi,
I have a similar problem with my 930 BF. I am having difficulty finding the 820uf 25 v caps at the local stores and I am wondering if it's okay to replace them with 1000uf 25v caps?
Thanks in advance.

[PlainBill]

Re: Samsung 930b LCD cold start problem (inverter?)

Hi,
I have a similar problem with my 930 BF. I am having difficulty finding the 820uf 25 v caps at the local stores and I am wondering if it's okay to replace them with 1000uf 25v caps?
Thanks in advance.

A few suggestions: Make sure the replacements will fit.

Try to keep the overall capacitance the same. Replacing three 820uF with two 1000uF and one 470uF would do that.

Use only name brand low ESR such as Panasonic FM or equivalent series from United Chemicon, Nichicon, or Rubycon. 85°C caps from Radio Shack won't work.

PlainBill

[jetadm123]

Re: Samsung 930b LCD cold start problem (inverter?)

Hello! If you're located in the USA, then you can order some Panasonic FM series through digikey.com. Part # is: P12391-ND (820uf@25V).

Make sure the size (height and diameter) listed will fit your board. And choose USPS First Class shipping for the cheapest ship rate.

[balenu]

Re: Samsung 930b LCD cold start problem (inverter?)

Thanks for your fast responses.
Sadly I do not live in the USA (I'm from Romania) so I will order online from a site I found some Panasonic caps but it will take a couple of days(that's why I wanted to buy from my local store).

[demens]

Re: Samsung 930b LCD cold start problem (inverter?)

My frustration continues.

Like an idiot, i was stubborn enough to wait for these free samples, totally not worth it, better off just buying them. I finally got them today, all but 1 cap. Replaced all the caps i had and still the same problem. I seem to be making progress as the hissing noise is on for less then 5 min. when before it would take from 30 to an hour or more. Once the hissing stops the monitor works fine, although i didnt even test it this time.

I've been trying to isolate the noise but it seems like its coming from everywhere (on the power supply). Could 1 bad cap cause all the others to make noise?

[retiredcaps]

Re: Samsung 930b LCD cold start problem (inverter?)

I've been trying to isolate the noise but it seems like its coming from everywhere (on the power supply). Could 1 bad cap cause all the others to make noise?

Post clear focused pictures AFTER reading

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

DO NOT post pictures inline.

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 focus pictures. Try to get a photo that is 2000x2000 resolution or as close as possible.

[demens]

Re: Samsung 930b LCD cold start problem (inverter?)

Pics. The only one not replaced is the small black one in the 3rd pic and the 1 in the middle of the 2nd pic by itself. Noone has mentioned replacing that 2nd one.

I ordered both from digikey today, but somehow i dont think the noise will stop after i replace those.