Twin Samsung 931b monitors

[EGuevarae]

Re: Twin Samsung 931b monitors

No, it is not the cost of capacitors. It is that this SMPS was designed to work with cheap capacitors and using LowESR in such circuits can be detrimental to the SMPS performance, especially in terms of ripple.

LowESR does not necessarily mean good performance nor long life.

Actually, you have to try it out. Sometimes it is better to make as little alterations to the circuit as possible.

Actually, my guess is that it was designed to work with not-so-bad capacitors but they were replaced either to reduce costs at mass production or simply because that was the brand/type at hand at that time.

[almoodie]

Re: Twin Samsung 931b monitors

You'd better open it up again and make sure. Here are the Digikey part numbers and the Panasonic part numbers for the caps. Note most of them are available in two sizes. Choose First Class mail shipping for low cost and speedy delivery.

2 @ 820 microfarad 25V P11221-ND EEU-FC1E821 2 @ $1.07 OR P11222-ND EEU-FC1E821S 2 @ $1.30

1 @ 470 microfarad 25V P12389-ND EEU-FM1E471L 1 @ $.43 OR P12388-ND EEU-FM1E471 1 @ $.50

2 @ 1000 microfarad 10V P12353-ND EEU-FM1A102 2@ $.50 OR P12354-ND EEU-FM1A102L @ $.50

1 @ 330 microfarad 10V P11184-ND EEUFC1A331 1 @ $.48

1 @ 1 microfarad 50V P10312-ND EEUFC1H1R0 1 @ $.27

PlainBill

Ordered the caps from digikey.com, took the monitor apart and replaced them all, monitor works like new. Thanks to all,
Al Moodie.

[PlainBill]

Re: Twin Samsung 931b monitors

Ordered the caps from digikey.com, took the monitor apart and replaced them all, monitor works like new. Thanks to all,
Al Moodie.

Give yourself an 'Attaboy' for that!!!

PlainBill

[EGuevarae]

Re: Twin Samsung 931b monitors

Ordered the caps from digikey.com, took the monitor apart and replaced them all, monitor works like new. Thanks to all,
Al Moodie.

Good job buddy!

[pixel8ed]

Re: Twin Samsung 931b monitors

Hit a snag with my re-capping project. The two biggest caps, the 880uf 25v replacement caps are too large. The replacement size is 0.492" Dia x 0.787" H (12.50mm x 20.00mm).

Diameter is perfect, but it is about .25" too tall. So when I put the board back in the case, the caps butt right up against the metal panel. It looks like it's still possible to screw the board down, but I'm wondering if the contact will cause problems. I can't find the proper size on Digi-Key. The caps that are shorter are wider also, and the way these sit next to each other, there doesn't seem like there would be room.

[PlainBill]

Re: Twin Samsung 931b monitors

Hit a snag with my re-capping project. The two biggest caps, the 880uf 25v replacement caps are too large. The replacement size is 0.492" Dia x 0.787" H (12.50mm x 20.00mm).

Diameter is perfect, but it is about .25" too tall. So when I put the board back in the case, the caps butt right up against the metal panel. It looks like it's still possible to screw the board down, but I'm wondering if the contact will cause problems. I can't find the proper size on Digi-Key. The caps that are shorter are wider also, and the way these sit next to each other, there doesn't seem like there would be room.

You better assume the cap contacting the case will cause problems. A few ideas:

1. If the contact is VERY light, cover the cap with a piece of light plastic or cardboard - something about the thickness of a playing card is sufficient.

2. Mark the spot on the case where the cap contacts it. Lay the case on a piece of soft wood, then hit the case on the inside to make a dimple. A ball peen hammer is a good tool for this. Think of the result as a miniature version of the cupola being installed on the space station.

3. Cut a hole in the case so the cap can poke through

PlainBill

[pixel8ed]

Re: Twin Samsung 931b monitors

Thanks for the advice PlainBill... I'll give those a shot. A playing card should do the trick.

I messed up on reporting the sizes. Not that it's a big deal, but I'll post the correction below for anyone else working on this same project.

=================

The 820 microfarad 25V P11221-ND EEU-FC1E821 cap is 0.394" Dia x 0.984" H (10.00mm x 25.00mm).

Which is about .25" too tall. The next size down would be 0.492" Dia x 0.787" H. The height would probably be perfect, but the diameter is much wider, and because of how close the two caps sit next to each other, this probably won't work.

[Pyr0Beast]

Re: Twin Samsung 931b monitors

Actually. Making a big hole near the caps would be a great solution as it will provide the much needed cooling as well - and where you need it most.

Case is grounded and as such shouldn't cause any issues. Capacitors' case isn't grounded but it is floating at some voltage. Even scotch tape would work, but heat will take its toll and the glue will dry, so the piece will fall off eventually (if the cap isn't holding it.
Perhaps even some masking tape would be good if you cover metal, not the caps with it.

[brh8]

Re: Twin Samsung 931b monitors

Thanks for this forum - I only had one cap go bad, replaced it the same 1000u 16v, put it all back together, works like new.... my issue: it would take forever to come on, then just stop coming on..

[alandoud]

Re: Twin Samsung 931b monitors

My problem is figuring out how to open the housing on the Samsung 921B. I see a lock knock out but can't figure if that is for releasing housing and what kind of tool if this is the case.

I am novice at this and am aware of caps dangers. Unfortunately my good friend and adviser died recently.

Can the cap be discharged merely by grounding or jumping across terminals without a resitor and do you have to discharge before desoldering.

[retiredcaps]

Re: Twin Samsung 931b monitors

My problem is figuring out how to open the housing on the Samsung 921B. I see a lock knock out but can't figure if that is for releasing housing and what kind of tool if this is the case.

Taking apart LCD video.

http://www.youtube.com/watch?v=Ul5LhuCT1y8

Can the cap be discharged merely by grounding or jumping across terminals without a resitor and do you have to discharge before desoldering.

I'm told that most caps in the LCD will discharge after 1 minute. If you want to manually discharge the large cap, see

http://www.repairfaq.org/sam/smpsfaq.htm#smpssafdc

PS. If your monitor is a Samsung 921B, start a new thread as not to pollute the 931B thread.

[Wrog]

Re: Twin Samsung 931b monitors

My problem is figuring out how to open the housing on the Samsung 921B. I see a lock knock out but can't figure if that is for releasing housing and what kind of tool if this is the case.

The hole with the lock symbol is probably for attaching an anti-theft device (Kensington lock) and not for opening the housing.

[BitMan13]

Re: Twin Samsung 931b monitors

http://lcdalternatives.com/

I found this company when looking for replacement caps for my 931b. They sell kits containing all the caps you would need to replace for your model of LCD. I just ordered and will post how it all turns out.

[BitMan13]

Re: Twin Samsung 931b monitors

http://lcdalternatives.com/

I found this company when looking for replacement caps for my 931b. They sell kits containing all the caps you would need to replace for your model of LCD. I just ordered and will post how it all turns out.

New caps were delivered today, took about an hour to install and now the monitor is like new. Also came with a little solder so I didn't have to go digging around to try and find mine. I used a 25w iron, which may not be the best practice but it did the trick OK, and I am not an experienced solderer. I highly recommend this company if you are a little unsure about which caps to get for your monitor.

[marlonsing]

Re: Twin Samsung 931b monitors

It's definitely a good idea to replace all the caps with the possible exception of the large (typically 120 uF, 450 V cap). First of all, there are several caps (10-100 uF, 50 V) that can fail with no visible signs. When they do, the result is a dead monitor. Since these cost under $.30 each, replacing them is not a significant expense.

Second, the caps are failing because of inferior quality. Again, the cost of replacing those with no obvious problems is minimal. And it will avoid having a problem when they also fail in a few years.

PlainBill

hi,
i have the same problem with my samsung lcd tv..the model is ln46a500... there is no picture "black screen" and clicking sound, and i have read about the capacitor problem, but when i checked the capacitor of my power supply board the capacitor looks fine , no bulging...no indications that the capacitor is damaged. my question is, is it possible that the capacitor is damaged? and i even bought a power supply board from ebay...and it is used... and when i replaced mine.. it only works for a ouple of hours and then it goes back to the same old problem... my plan right now is i am going to replace all the capacitor even if it doesnt shows any physical damage.... im planning to replace the side where the 1000 microfarad 10v located.. and ive heared that its better to increase the voltage of the capacitor... any advice please... thank you

[PlainBill]

Re: Twin Samsung 931b monitors

hi,
i have the same problem with my samsung lcd tv..the model is ln46a500... there is no picture "black screen" and clicking sound, and i have read about the capacitor problem, but when i checked the capacitor of my power supply board the capacitor looks fine , no bulging...no indications that the capacitor is damaged. my question is, is it possible that the capacitor is damaged? and i even bought a power supply board from ebay...and it is used... and when i replaced mine.. it only works for a ouple of hours and then it goes back to the same old problem... my plan right now is i am going to replace all the capacitor even if it doesnt shows any physical damage.... im planning to replace the side where the 1000 microfarad 10v located.. and ive heared that its better to increase the voltage of the capacitor... any advice please... thank you

I'm wondering if there is another problem. Ordinarily I'm slightly suspicious of 'used' parts. In some cases unethical sellers use that ploy to get rid of their junk. Still, the fact that the replacement supply developed the same problem within a few hours is definitely unusual. A quick test - does the power supply work if the logic card is disconnected?

PlainBill

[apster07]

Re: Twin Samsung 931b monitors

Ordered the caps from digikey.com, took the monitor apart and replaced them all, monitor works like new. Thanks to all,
Al Moodie.

Did you ever find out the diameters of the capacitors so i can purchase them myself?! i have the same exact monitor, im so lost!

[retiredcaps]

Re: Twin Samsung 931b monitors

Manufacturers can and have used different power boards and revisions, but keep the same model number. Therefore, it is best if you measure the height and diameter and record the uF and voltage of your own board.

If you live in the USA, follow PlainBill's instructions to order Panasonic FR or FM. If they are not available, then choose FC.

https://www.badcaps.net/forum/showpo...33&postcount=2

[apster07]

Re: Twin Samsung 931b monitors

Manufacturers can and have used different power boards and revisions, but keep the same model number. Therefore, it is best if you measure the height and diameter and record the uF and voltage of your own board.

If you live in the USA, follow PlainBill's instructions to order Panasonic FR or FM. If they are not available, then choose FC.

https://www.badcaps.net/forum/showpo...33&postcount=2

How do i go about measuring the height? whats the best way? PlainBill gave the model numbers from digikeys websites, but like he said theres more then 1 or 2 sizes for most..im just kind of lost on how im supposed to go about measuring the heights and diameters of these capacitors so i know which one to get =\

[retiredcaps]

Re: Twin Samsung 931b monitors

How do i go about measuring the height? whats the best way?

Use a standard ruler and measure in millimeters. If you don't have one, print one by searching for "printable ruler".