Samsung UE40C6000RWXXN clicking power board issue

[dick_barton]

Re: Samsung UE40C6000RWXXN clicking power board issue

There are 8 pins on ICM802
Pin 1 = ??
Pin 2 = ??
etc
Pin 8 = ??
But be very careful not to slip with your meter probe when measuring the voltages.

[budm]

Re: Samsung UE40C6000RWXXN clicking power board issue

I do not see the PFC Voltage report, is it still at 388Vdc as the before the accident happen?
BTW, this power supply board is know for bad solder joints, especially around the transformer legs that are soldered through the thru-hole rivets.

[sepper]

Re: Samsung UE40C6000RWXXN clicking power board issue

There are 8 pins on ICM802
Pin 1 = ??
Pin 2 = ??
etc
Pin 8 = ??
But be very careful not to slip with your meter probe when measuring the voltages.

GD1 5
VCC 13
GND 0
GD2 5

DT 2.2
RT 2.5
OC 0.7
SS 2.2-5 switching

[sepper]

Re: Samsung UE40C6000RWXXN clicking power board issue

I do not see the PFC Voltage report, is it still at 388Vdc as the before the accident happen?
BTW, this power supply board is know for bad solder joints, especially around the transformer legs that are soldered through the thru-hole rivets.

If I measure between CP803 - leg and RM814 I get 388V

[budm]

Re: Samsung UE40C6000RWXXN clicking power board issue

I would check the resistance of the resistor network for the protection circuit RM814~818, 825.

[sepper]

Re: Samsung UE40C6000RWXXN clicking power board issue

I would check the resistance of the resistor network for the protection circuit RM814~818, 825.

I only get 500k Ohm on my RM814 RM815 and RM817 should I get 1M instead?

RM816 - 950k ohm
RM818 - 17.8k ohm
RM825 - 17.9k ohm

[dick_barton]

Re: Samsung UE40C6000RWXXN clicking power board issue

ICM801 appears to have a good working VCC. The data sheet says when VCC exceed 10.5V the device is enabled.

SS switching is odd so as BudM says checking those resistors would be a good step.
Does your power supply match the schematic diagram in this thread
RM814 & RM815 = 910K
RM816 & RM817 = 1M

The resistors should read those values but sometimes when in circuit they do not read correctly so I normally unsolder them to check.

[sepper]

Re: Samsung UE40C6000RWXXN clicking power board issue

ICM801 appears to have a good working VCC. The data sheet says when VCC exceed 10.5V the device is enabled.

SS switching is odd so as BudM says checking those resistors would be a good step.
Does your power supply match the schematic diagram in this thread
RM814 & RM815 = 910K
RM816 & RM817 = 1M

The resistors should read those values but sometimes when in circuit they do not read correctly so I normally unsolder them to check.

My power supply is 220v ac or isnt that what you mean? Mmmm never soldered smd before. I give it a try tomorrow.

[dick_barton]

Re: Samsung UE40C6000RWXXN clicking power board issue

I mean the voltage needed to operate the IC appears to be within spec.
Don't lose the resistors when you unsolder them so best do one at a time.

[sepper]

Re: Samsung UE40C6000RWXXN clicking power board issue

I mean the voltage needed to operate the IC appears to be within spec.
Don't lose the resistors when you unsolder them so best do one at a time.

I unsoldered RM814 and it was 910k all the other values where ok too on circuit. So no need to unsolder them I guess?

[dick_barton]

Re: Samsung UE40C6000RWXXN clicking power board issue

Can you check the voltage across the legs of capacitor CM806. If the voltage is not stable can you take it out and check the value is still 47uF

[sepper]

Re: Samsung UE40C6000RWXXN clicking power board issue

Can you check the voltage across the legs of capacitor CM806. If the voltage is still switching can you take it out and check the value is still 47uF

13v without switching

I measure a stable 5.8v over CM803 but on CM802 I measure 0.8v. Is this weird?

[dick_barton]

Re: Samsung UE40C6000RWXXN clicking power board issue

According to section 7.3.1 once the voltage at SS increases beyond 1.2V the IC starts to generate gate-drive signal.
It looks as though the IC must be trying to start but failing for some reason and restarting.

I'm out of idea's at the moment but maybe someone else can offer further help.

[dick_barton]

Re: Samsung UE40C6000RWXXN clicking power board issue

13v without switching

I measure a stable 5.8v over CM803 but on CM802 I measure 0.8v. Is this weird?

CM803 is connected to ICM802 (SS pin) = 5.8V
SS => 1.2V to drive the mosfets so that looks OK

CM802 connected to ICM802 (OC) = 0.8V
Should be <= 0.6V for soft start to recover.

Have you checked the two smaller fuses for continuity.

Other than that I'm still none the wiser at this point other than maybe try a replacement UC25600 which are not expensive.

[sepper]

Re: Samsung UE40C6000RWXXN clicking power board issue

CM803 is connected to ICM802 (SS pin) = 5.8V
SS => 1.2V to drive the mosfets so that looks OK

CM802 connected to ICM802 (OC) = 0.8V
Should be <= 0.6V for soft start to recover.

Have you checked the two smaller fuses for continuity.

Other than that I'm still none the wiser at this point other than maybe try a replacement UC25600 which are not expensive.

FM801S is this a diode fuse? Because one side is 1.2k ohm other side is OL.
Other fuse is Ok.

[dick_barton]

Re: Samsung UE40C6000RWXXN clicking power board issue

I've put red arrows showing the two fuses Post #34. They are small metal capped ceramic fuses. You need the set switched off and then measure using your meter set to ohms across each of them in turn.

[budm]

Re: Samsung UE40C6000RWXXN clicking power board issue

Hmm, I thought the simple test of the fuses were done per post #1 already and they were fine, right?
"I don't know where to look now. I have a multi meter and tried to check some fuses and they look ok on the board. Any tip where to look now?"

[sepper]

Re: Samsung UE40C6000RWXXN clicking power board issue

Hmm, I thought the simple test of the fuses were done per post #1 already and they were fine, right?
"I don't know where to look now. I have a multi meter and tried to check some fuses and they look ok on the board. Any tip where to look now?"

Yes. The fuses are ok.

FB801S 0.5 ohm

FM801s 1.2k ohm in one direction and other direction open circuit... So it's acting like a diode as I already asked. It's not really saying something about that on the diagram or do I need to unsolder it.

[budm]

Re: Samsung UE40C6000RWXXN clicking power board issue

Fuses on that board should all show < 1 Ohms (depend on your probe leads resistance), if not then it is bad.

[sepper]

Re: Samsung UE40C6000RWXXN clicking power board issue

Fuses on that board should all show < 1 Ohms (depend on your probe leads resistance), if not then it is bad.

Ok, I think we have a winner... I unsoldered it. Gives OL. So its 100% broken.

Can I just bridge it for a quick test or is this not done?