Samsung Ln55b650t1f Part Identification

[philtvman]

Re: Samsung Ln55b650t1f Part Identification

Check cable from powerboard to mainboard, see if there are any dark or burnt looking terminals, can also check for continuity from end to end, Sometimes I use stripped bread ties so as not to spread out or distort the terminal ends.

Reply above, meant to quote it you

[philtvman]

Re: Samsung Ln55b650t1f Part Identification

No change in voltages when the T-Con was removed from the Main.

Also thoroughly looked over the Main/Power cable, everything looks good there.

Thanks for your help!

[nomoresonys]

Re: Samsung Ln55b650t1f Part Identification

Check cable from powerboard to mainboard, see if there are any dark or burnt looking terminals, can also check for continuity from end to end, Sometimes I use stripped bread ties so as not to spread out or distort the terminal ends.

[nomoresonys]

Re: Samsung Ln55b650t1f Part Identification

Maybe unhook the tcon from mainboard, keep mainboard connected to powerboard, see if you get proper steady voltages there at your powerboard connector.

[philtvman]

Re: Samsung Ln55b650t1f Part Identification

So what Voltage do you have on INV-ON and I-PWM pins when running the power supply board without connection to the main board but everything else are still connected? Do see the backlights come on?

Yes, the backlights all come on with the main board disconnected.

INV-ON: 7.3
I-PWM: No wire in this connection
E-PWM: 4.9

Correct, the standby light will be on when the TV is OFF and turn off when the power button is pressed. It turns back on after about 2 seconds.

[philtvman]

Re: Samsung Ln55b650t1f Part Identification

Interesting... can you check the four rectifying diodes on that power board? Wait until the big caps discharge first. If you can, either remove the diode from the circuit, or just lift one leg off first.

Are these the four you are referencing? Thank you for your patience!

[budm]

Re: Samsung Ln55b650t1f Part Identification

So what Voltage do you have on INV-ON and I-PWM pins when running the power supply board without connection to the main board but everything else are still connected? Do see the backlights come on?

[budm]

Re: Samsung Ln55b650t1f Part Identification

Voltage between filter caps
Power Off with Main Disconnected from PS: 387
Power Off All Connected: 168
Power On: Spikes to 387 and drops back to 168

Tested the SB and yes, same result. Steady at 5.18 with Power Off.
When Powered on, voltage jumps from 5.18 -> 3.31 -> 0.155 -> 1.3 -> 1.6 -> OL -> 5.18 (all in about 2 seconds)...when the button is pressed and these voltages are bouncing around, the standby light turns off.

So in self test mode (power supply board not connected to the main board) the PS-ON pin has the pull-up resistor to simulate PS-ON control signal and the PFC Boosted Voltage is working fine,

[budm]

Re: Samsung Ln55b650t1f Part Identification

Voltage between filter caps
Power Off with Main Disconnected from PS: 387
Power Off All Connected: 168
Power On: Spikes to 387 and drops back to 168

Tested the SB and yes, same result. Steady at 5.18 with Power Off.
When Powered on, voltage jumps from 5.18 -> 3.31 -> 0.155 -> 1.3 -> 1.6 -> OL -> 5.18 (all in about 2 seconds)...when the button is pressed and these voltages are bouncing around, the standby light turns off.

Ah, so the standby light does not stay on solid then, that this important if, unless I read your post #1 wrong and thinking that the standby light stay on when turn the TV on and then goes off when TV is turned off.
So right now we do not have steady Standby power supply output.

[ngth82]

Re: Samsung Ln55b650t1f Part Identification

Interesting... can you check the four rectifying diodes on that power board? Wait until the big caps discharge first. If you can, either remove the diode from the circuit, or just lift one leg off first.

[philtvman]

Re: Samsung Ln55b650t1f Part Identification

+1 to BudM and the big scary cap comment. It's no joke. Don't die.

Just getting to my e-mail... standby goes down to 1.3V? STBY isn't loaded down when the TV is off (e.g it's within nominal), and shouldn't be when the TV is on.

Edit: also, you are missing a few pin numbers... You have pins 1, 2, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 30... where are the rest?

Correct. When Powered on, standby voltage jumps from 5.18 -> 3.31 -> 0.155 -> 1.3 -> 1.6 -> OL -> 5.18 (all in about 2 seconds)

All the pins I left out are not wired, just open holes in the connector.

[philtvman]

Re: Samsung Ln55b650t1f Part Identification

What DC V do you have between the two legs of the main filter caps (two 450vdc LARGE CAPS laying on the side in t he HOT DEADLY SIDE of the circuit) when power switch is OFF and when it is on?

Post #15:
"3 SB 5.18 1.3"
Are you 100% sure that the SB (5V Standby power supply) drops down to 1.3V? I cannot see why you will have standby LED comes on when standby power supply drops down to 1.3V.

Voltage between filter caps
Power Off with Main Disconnected from PS: 387
Power Off All Connected: 168
Power On: Spikes to 387 and drops back to 168

Tested the SB and yes, same result. Steady at 5.18 with Power Off.
When Powered on, voltage jumps from 5.18 -> 3.31 -> 0.155 -> 1.3 -> 1.6 -> OL -> 5.18 (all in about 2 seconds)...when the button is pressed and these voltages are bouncing around, the standby light turns off.

[ngth82]

Re: Samsung Ln55b650t1f Part Identification

+1 to BudM and the big scary cap comment. It's no joke. Don't die.

Just getting to my e-mail... standby goes down to 1.3V? STBY isn't loaded down when the TV is off (e.g it's within nominal), and shouldn't be when the TV is on.

Edit: also, you are missing a few pin numbers... You have pins 1, 2, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 30... where are the rest?

[budm]

Re: Samsung Ln55b650t1f Part Identification

What DC V do you have between the two legs of the main filter caps (two 450vdc LARGE CAPS laying on the side in t he HOT DEADLY SIDE of the circuit) when power switch is OFF and when it is on?

Post #15:
"3 SB 5.18 1.3"
Are you 100% sure that the SB (5V Standby power supply) drops down to 1.3V? I cannot see why you will have standby LED comes on when standby power supply drops down to 1.3V.

[philtvman]

Re: Samsung Ln55b650t1f Part Identification

what is the power supply board p/n? Bn44 -?????
Your readings do not look right at all.

bn44-00268a

[budm]

Re: Samsung Ln55b650t1f Part Identification

What is the power supply board P/N? BN44 -?????
Your readings do not look right at all.

[philtvman]

Re: Samsung Ln55b650t1f Part Identification

Can you get some good clear head on shots of the main board? Preferably in natural light - no flash.

Look at your meter. Turn it on and into resistance mode.

• When you don't have the probes touching each other, what reading do you get? (OL or something similar).
• Touch the probes together -- what reading do you get now? (0.00 ohm, or something under 1 ohm is what we're looking for.).

If you get something in the ~10 ohm region, i'm assuming that you didn't break through the thin layer of oxidation on the probe. A good test is to get a piece of copper and lightly "jam" the tip into the copper for a good connection.

Anyway, back to your TV: the inductor should have 0 resistance (for the sake of this discussion). There are parasitic resistances for it in a "real inductor" vs an "ideal inductor" (quick google search will have some physics background for this)

Do you have a photo of the board before you removed the inductor?

I'm assuming the connector by the barcode goes to the power board.

• Please post voltage readings with everything connected when the TV is OFF
• Post voltage readings with the TV is ON?

Make a table like this (example). Give the pin number. The signal name (as shown on the silk screen on the board), the OFF voltage, the ON voltage. Wrap it with the "code" block when you edit in "Go Advanced" mode to format it...

Pin	SIG	V_OFF	V_ON
1	PWR_ON	0	3.329
3	20V	0	21.26
5	GND	0	0
7	GND	0	0
9	3.5V	3.49	3.438
11	3.5V	3.49	3.438
13	GND	0	0

Full Model: LN55B650T1FUZA
P/N for the SMD near the Inductor: Z1021HAI

Here are the voltages I ended up with. I initially checked all capacitors on the PS and they verified okay.

Pin #	Sig	v_off	v_on
1	PS	0	0.1
2	Sync	0	0
3	SB	5.18	1.3
5	GND	0	0
7	18V	0	1.5
9	GND	0	0
11	GND	0	0
13	5.1	0	0.5
15	5.1	0	0.5
17	GND	0	0
19	13	0	0.04
21	13	0	1.7
23	INV-ON	0	0
25	E-PWM	0	0.6
27	5V_DET	0	0
29	GND	0	0
30	GND	0	0

Thanks again for your help

[budm]

Re: Samsung Ln55b650t1f Part Identification

https://www.badcaps.net/forum/attach...1&d=1586578260
What is the P/N of that 8-pin SMD IC connected to that inductor?

[ngth82]

Re: Samsung Ln55b650t1f Part Identification

Yep. Solder the inductor back on.

Take readings with the tv off.
Then take readings with the tv on. This may take several on-off cycles. Since some of them will likely decay since the tv doesn’t turn on all the way.

[budm]

Re: Samsung Ln55b650t1f Part Identification

can you get some good clear head on shots of the main board? Preferably in natural light - no flash.

Look at your meter. Turn it on and into resistance mode.

• when you don't have the probes touching each other, what reading do you get? (ol or something similar).
• touch the probes together -- what reading do you get now? (0.00 ohm, or something under 1 ohm is what we're looking for.).

if you get something in the ~10 ohm region, i'm assuming that you didn't break through the thin layer of oxidation on the probe. A good test is to get a piece of copper and lightly "jam" the tip into the copper for a good connection.

Anyway, back to your tv: The inductor should have 0 resistance (for the sake of this discussion). There are parasitic resistances for it in a "real inductor" vs an "ideal inductor" (quick google search will have some physics background for this)

do you have a photo of the board before you removed the inductor?

I'm assuming the connector by the barcode goes to the power board.

• please post voltage readings with everything connected when the tv is off
• post voltage readings with the tv is on?

make a table like this (example). Give the pin number. The signal name (as shown on the silk screen on the board), the off voltage, the on voltage. Wrap it with the "code" block when you edit in "go advanced" mode to format it...

pin	sig	v_off	v_on
1	pwr_on	0	3.329
3	20v	0	21.26
5	gnd	0	0
7	gnd	0	0
9	3.5v	3.49	3.438
11	3.5v	3.49	3.438
13	gnd	0	0

+1