Samsung UN65JS9500 / BN44-00818A - no LED backlight

[realfastbug]

Re: Samsung UN65JS9500 / BN44-00818A - no LED backlight

ok, I jumped the gun. The fuse is blown. I removed the primary side fets and they are shorted but the gate drive resistors and the fast-off gate drive res-diode groups look to be ok. The secondary fets also look ok. However, I realized this board has been sent in for repair already as all of these parts had already been changed before. I will see if I can find more into on who did the repair. The primary fets had been changed out with a slightly different part with lower gate charge but the specs seem similar enough I would have expected they would have survived. The original K15A50D were replaced with K20A60U FETs .

[silentkav]

Re: Samsung UN65JS9500 / BN44-00818A - no LED backlight

RM911 and RM912 both show 100ohms on mine. In fact I went to the extent of checking all the resistors in the circuit and all checked out. On mine, I do not seem to get getting power to drive the ICM901 which would then enable the QM901 and QM902 fets.

[R_J]

Re: Samsung UN65JS9500 / BN44-00818A - no LED backlight

Check if you have vcc voltage on pin 7, or across CM901. I believe it is a SEM3110a, Not a adp3110a
Check if pin 6 is hot ground

[silentkav]

Re: Samsung UN65JS9500 / BN44-00818A - no LED backlight

Without the IC installed PIN 7 is showing 15.3x V with PIN 6
Across CM901 its 15.4 V

We probably don't have a SEM3110A datasheet? I've been trying to find a fault based on the ADP IC.

[R_J]

Re: Samsung UN65JS9500 / BN44-00818A - no LED backlight

I believe the UCC25600 is a similar ic, That 15 volts is likely ok for the vcc

[realfastbug]

Re: Samsung UN65JS9500 / BN44-00818A - no LED backlight

Check if you have vcc voltage on pin 7, or across CM901. I believe it is a SEM3110a, Not a adp3110a
Check if pin 6 is hot ground

That makes more sense as there is a cap going to pin4 and measured around 4v.

[R_J]

Re: Samsung UN65JS9500 / BN44-00818A - no LED backlight

With 4v on pin4, the soft start should be complete and the ic is operating. Do you have any vcc voltage on QM905 or QM901? Check RM924
Also check that CM906CS is good, if open the transformer has no return to ground. This type of cap can bulge if bad

[silentkav]

Re: Samsung UN65JS9500 / BN44-00818A - no LED backlight

If the fuse between the 3 large capacitors and the fets is blown you have a very good chance that QM901CS at a minimum is bad.

I replaced the fuse on my first try, when powered up it snapped immediately. Since replacing QM901CS and QM902CS the fuse no longer blows but still it still does not output to the LED Board nor are there voltages to the transformer from the fets so as others have stated in my case it's likely the original IC which was also damaged.

Based on some of the latest conversations, my previous testing was based on the datasheet from the incorrect IC and when looking at the latest suggestion datasheet it makes more sense as you had also mentioned. I have ordered a couple of IC's and should have an update mid next week on my progress.

[realfastbug]

Re: Samsung UN65JS9500 / BN44-00818A - no LED backlight

hopefully I can get back to this next week. I did confirm with my brother that he sent this out and the primary and secondary fets were replaced along with the fuse. He said is worked for a few hours then failed again, that's when he dropped it off at my house and said have fun. One thing I noticed is the pcb seems to be a little discolored on the secondary side area between the transformer and the fets like it got hot. maybe just the repair guy was over zealous.

[nomoresonys]

Re: Samsung UN65JS9500 / BN44-00818A - no LED backlight

hopefully I can get back to this next week. I did confirm with my brother that he sent this out and the primary and secondary fets were replaced along with the fuse. He said is worked for a few hours then failed again, that's when he dropped it off at my house and said have fun. One thing I noticed is the pcb seems to be a little discolored on the secondary side area between the transformer and the fets like it got hot. maybe just the repair guy was over zealous.

Is the driver IC ok?

[realfastbug]

Re: Samsung UN65JS9500 / BN44-00818A - no LED backlight

Is the driver IC ok?

I haven't verified the control IC yet other than I can say that the place that repaired the board did not replace it. The gate drive resistors were ok though. My brother said it worked for a few hours then the PS blew up again so it must have an issue beyond the fets that were replaced.

[Joseph MARTIN]

Re: Samsung UN65JS9500 / BN44-00818A - no LED backlight

What reference ICM852 and ICM952

[Joseph MARTIN]

Re: Samsung UN65JS9500 / BN44-00818A - no LED backlight

On this PCB board, the backlighting is provided by a TM901CS mid-point transformer. The rectifier diodes are replaced by mosfet QM952 and QM951. The gates are controlled by the ICM952 circuit (S742 !!!), what is the reference of this circuit ? Thank you for your understanding for my troubleshooting

[Joseph MARTIN]

Re: Samsung UN65JS9500 / BN44-00818A - no LED backlight

What reference ICM852 and ICM952

On this PCB board, the backlighting is provided by a TM901CS mid-point transformer. The rectifier diodes are replaced by mosfet QM952 and QM951. The gates are controlled by the ICM952 circuit (S742 !!!), what is the reference of this circuit ? Thank you for your understanding for my troubleshooting

merci

[Joseph MARTIN]

Re: Samsung UN65JS9500 / BN44-00818A - no LED backlight

merci

ok

[Joseph MARTIN]

Re: Samsung UN65JS9500 / BN44-00818A - no LED backlight

12

[Joseph MARTIN]

Re: Samsung UN65JS9500 / BN44-00818A - no LED backlight

reponse

[Joseph MARTIN]

Re: Samsung UN65JS9500 / BN44-00818A - no LED backlight

Schéma Vdr

[Joseph MARTIN]

Re: Samsung UN65JS9500 / BN44-00818A - no LED backlight

[QUOTE=Joseph MARTIN;1007806]service maual/QUOTE]

[Joseph MARTIN]

Re: Samsung UN65JS9500 / BN44-00818A - no LED backlight

[QUOTE=Joseph MARTIN;1007841]

service manual/QUOTE]

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