Samsung LN40A550P3F 40" HDTV, slow to turn on

[samsonite]

Hello,
I have a Samsung LN40A550P3F 40" HDTV. Bought in 2008, so it's about 10 years old.

For the last couple of months, it's been slow to turn on in the morning. I've timed it, and
it's anywhere between 5 and 10 minutes. The TV has a red power light that continuously blinks
until the TV turns on.

I recently took the back off, and looked at the caps, but they all look ok to me. No bulging caps.
I'm the original owner, and the power board appears to be in pristine condition.

I didn't know what else to do, so I bought a "refurbished" power board from ShopJimmy for 50 bucks.
They sent me a beat up board, dusty and scratched, with the corner of the circuit board cracked and
hot-glued together. This was the first time I have ever used ShopJimmy, so I was shocked they
sent me a Frankenstein board.

Anyway, I replaced the power board, and after a day or so, nothing has changed.
The TV still takes several minutes to turn on in the morning.

If replacing the power board didn't solve the problem, what else can be done?

Another question, what exactly happens when the TV is turned off and is in standby mode?
Should the TV still maintain the charge on the caps, so the TV can turn on quickly for the
next time? Thanks.


Stamped on power board:
Hansol LCD
3925310014AD
Rev 1.2
30 Jan 08
SIP408A

Part number (power supply):
BN4400197A

Part bought:
http://www.shopjimmy.com/samsung-bn4...t-inverter.htm

This board has two large 450V 100uF caps, and some other smaller caps. It also has a small,
removable fuse, described as T6.3AH250V.

[tvtimmy]

Re: Samsung LN40A550P3F 40" HDTV, slow to turn on

On the back of the main board(video input) there is a 47uf capacitor at c102 that is bad.
It is a 10v 47uf. Put in a higher voltage rated one.

[samsonite]

Re: Samsung LN40A550P3F 40" HDTV, slow to turn on

Thanks for the reply.

My main video board:
BN94-02077C

Found a replacement, but out of stock:
https://www.shopjimmy.com/samsung-bn...a550p3fxza.htm

Found a repair video, but I have no heat gun for surface mount work, just a 45W desoldering iron:
https://www.youtube.com/watch?v=oC4f2Ik8rCI

[CapLeaker]

Re: Samsung LN40A550P3F 40" HDTV, slow to turn on

all you need is a replacement cap (can be even a regular electrolytic capacitor).
Read up on this thread from budm. https://www.badcaps.net/forum/showth...highlight=c102

[samsonite]

Re: Samsung LN40A550P3F 40" HDTV, slow to turn on

Thanks, I may try it.

Just a question, in the repair video, they were using solder paste. I'm assuming solder paste is only practical for heat gun owners, not for soldering irons?

[samsonite]

Re: Samsung LN40A550P3F 40" HDTV, slow to turn on

How big of a SMD component can I fit in C102? I looked at 10v and 16v capacitors on digikey, and the SMD dimensions increase
with larger voltage. I found these lines:

C102
2409-001118
Samsung C-polymer,Chip;47uf,20%,10v,wt,tp,3.5x2

Must SMD stay within same size of 3.5mm x 2mm ?

Maybe this one:
AVX Tantalum Capacitor
https://www.digikey.com/product-deta...3-1-ND/4005652

[samsonite]

Re: Samsung LN40A550P3F 40" HDTV, slow to turn on

all you need is a replacement cap (can be even a regular electrolytic capacitor).
Read up on this thread from budm. https://www.badcaps.net/forum/showth...highlight=c102

Ah, I didn't know what you mean until I saw this thread:
https://www.badcaps.net/forum/showth...highlight=c102

He replaced the SMD with a radial lead capacitor. Nifty.

Just wondering if my board will screw back into place after putting a big capacitor like that behind it?
I could do that instead of chasing around for the perfect SMD component.

Found two SMDs that should fit:

47uF Molded Tantalum Polymer Capacitor 10V, (3.50mm x 2.80mm)
https://www.digikey.com/products/en?...=399-4981-1-ND

47uF Molded Tantalum Polymer Capacitor 12.5V, (3.50mm x 2.80mm)
https://www.digikey.com/products/en?...399-18658-1-ND

[CapLeaker]

Re: Samsung LN40A550P3F 40" HDTV, slow to turn on

just leave the leads longer and bend the cap over 90 degrees instead of standing up like in post #5 of that particular thread. Just be careful with the polarization (+ and - ) of the cap.

[samsonite]

Re: Samsung LN40A550P3F 40" HDTV, slow to turn on

Well, I was able to order some capacitors from Digikey, but I've got a small problem. My 25W soldering iron doesn't seem to be hot enough to melt these contact points. No solder is coming off.

If I solder capacitor leads across this SMD chip, will it be a problem if the capacitance doubles from 47uf to 94uf?

[nomoresonys]

Re: Samsung LN40A550P3F 40" HDTV, slow to turn on

Hmm, 45 should be good, I've done it with an old abused 30W.

[samsonite]

Re: Samsung LN40A550P3F 40" HDTV, slow to turn on

Sorry, typo. Only 25w.

[CapLeaker]

Re: Samsung LN40A550P3F 40" HDTV, slow to turn on

If I solder capacitor leads across this SMD chip, will it be a problem if the capacitance doubles from 47uf to 94uf?

there is no 47uf in that old cap, other than that the TV would work. Sure you can double them up like that, but I don't recommend as it spells for trouble later. Take a sharp pair of side cutters and cut the old cap in half. Then unsolder the remains.

[nomoresonys]

Re: Samsung LN40A550P3F 40" HDTV, slow to turn on

Sorry, typo. Only 25w.

Ah I see, yep I think 25 is a little weak, 40W isn't bad for work like this.

[samsonite]

Re: Samsung LN40A550P3F 40" HDTV, slow to turn on

Thanks for the advice. I think I'm gonna put everything on hold for a week until I can get the right tools for the job. A 40w iron sounds just about right. Thanks.

[samsonite]

Re: Samsung LN40A550P3F 40" HDTV, slow to turn on

Just an update. I finally got a 40w iron, and... the solder still won't flow. It must be spot-welded on or something.

I went for plan B, and solder a 47uF cap across the SMD chip, making sure the leads matched the polarity of the SMD. I assume the marked end of the SMD chip is positive.

I turned on the TV, and nothing happened. The red LED light continues to blink on/off.

Meanwhile, the TV has gotten progressively worst. Before it took 10 minutes to turn on, now it takes over an hour. Not sure what to do next besides spending more money.

[samsonite]

Re: Samsung LN40A550P3F 40" HDTV, slow to turn on

Is it worth testing multimeter voltage levels? If the red LED light is blinking, can I assume the main board is getting 5V standby power? As the main board controls the blinking LED light, as well as the on/off signal from the remote control, which both seem to work?

I already replaced the power board, and that didn't fix the problem, so only the main board is left?

[aaronwt6]

Re: Samsung LN40A550P3F 40" HDTV, slow to turn on

Could we see a picture of your repair to verify it's correct?

[samsonite]

Re: Samsung LN40A550P3F 40" HDTV, slow to turn on

Sure, I added a before and after pics.

Looking at this pic in the link, it's hard to tell where they solder the negative end of the cap. Did they dig into the board and create a ground spot? Why didn't they solder it to the end of the SMD chip? Not enough room?

https://www.badcaps.net/forum/showth...highlight=c102

[aaronwt6]

Re: Samsung LN40A550P3F 40" HDTV, slow to turn on

It appears that you have the capacitor on correctly. I offer a repair service on these and have fixed 100s of them. I have run into cases where the boards were used for so long that the original issue caused something else to fail and the end result is just an indefinitely flashing light even after swapping the cap. Not saying if that's the case or not with yours but in that instance, I've never been able to get one going again.

[samsonite]

Re: Samsung LN40A550P3F 40" HDTV, slow to turn on

This video at 5:00 explains that both c102 and a nearby 8-pin IC chip should be replaced:
https://www.youtube.com/watch?v=oC4f2Ik8rCI

They also used a heat gun and tweezers to remove that stubborn SMD, btw. I don't have a heat gun, so I would
need some kind of heat clamp to remove the SMD in one go.

My IC chip says:
MP2363DN
83833419
MPS818

My Main Board:
BN41-00975B (2008.01.13)
MODEL: PEARL

This link doesn't describe the IC chip they sell:
https://www.shopjimmy.com/samsung-bn...a530p1fxza.htm

Is this the chip?
https://www.digikey.com/product-deta...366-ND/5299123

I could try replacing that as a last resort. Does that sound reasonable?