Re: Samsung LE32R88BD/ BN44-00155A
Alright!!! I ordered all the parts and just replaced them. (Both mosfets, the fuse resistor, the kV cap and the box cap). It works like a charm now!
Thank you budm !!!...
veaux
Member
Last Activity: 02-12-2025, 05:07 PM
Joined: 09-12-2014
Location: Monterrey, NL
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Re: Samsung LE32R88BD/ BN44-00155A
QM801 which is a FQPF5N50C from is Fairchild is apparently shorted. I have 1.5ohms between D-S, D-G and S-G.
The other one is apparently fine. I have no resistance reading (open circuit)...Leave a comment:
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Re: Samsung LE32R88BD/ BN44-00155A
unfortunately, I have no way to check capacitors (I should invest in one btw). How can I check the mosfets? Or, for the cost, I could replace them all maybe......Leave a comment:
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Re: Samsung LE32R88BD/ BN44-00155A
Alright, sorry for the delay. The main cap is at 175 V when the tv is on standby. When I try to power it on it doesn't change.
I checked the RM801 resistor and it has no continuity (infinite ohm reading).
As you'll see in the picture, there is a black trace bellow to blue capacitorCM818 apparently. I tried to remove the most glue I could. Kinda hard to do imho.
So what else do you think is fried beside the resistor? What can I check?
Thanks...Leave a comment:
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Re: Samsung LE32R88BD/ BN44-00155A
Hello budm, yes the photos are from before the caps replacement. I removed some of the glue, not all. I need to reopen the tv and finish the job. I'll check the 400V at that time.
I will post my findings when done....Leave a comment:
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Re: Samsung LE32R88BD/ BN44-00155A
GM folks, this thread is full of knowledge. I have the BN44-00192A which is apparently similar or even a drop in replacement of the one in this thread.
Symptom: solid red stdby led. Tv is responsive to remote... The led blinks when I use it but that's all.
I already replaced all the caps on the mainboard side, they were visually bad. But the problem is still here.... I'll look for that resistor next the the big cap on the primary.
5vsb is present and I have a 4.3V ish PS_ON for a couple seconds when I use...Leave a comment:
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Re: Samsung LN40B500P3F - Won't turn on
When it runs off it is like you pressed the standby button on the remote or like the tv had no power at all?...Leave a comment:
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Re: Samsung LN40B500P3F - Won't turn on
Hi, if sometimes it turns on and some time it doesn't, your issue is not the same as mine.
Mine was a shorted MOSFET that consecuently blown the fuse.
Who know is the PS board is bad on yours.Leave a comment:
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Re: Samsung LN40B500P3F - Won't turn on
Wuhu! I'm happy! I replaced the two MOSFETS and the TV is working like a charm!
I did my bulb box but I couldn't found a 100W incandescent bulb... tried with 70W but the TV went back stand by immedialety. So I tired direct and voila!
Posting a couple photos. TV Screen and Watt reading from the kill a watt.
Kudos to you budm, without your expertize I would't have been able to do it. It costed me 15bucks... And I still have 2 spare mosfets and some fuses! thank you!...Leave a comment:
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Re: Samsung LN40B500P3F - Won't turn on
I just need to find them now... not well deserved in electronics shops in Monterrey,MX... I'll have to go through Mouser or Digikey and end up paying more for the shipping than the components themselves!
I think this will take a couple of weeks to put my hands on a pair of new MOSFETS. I'll post the final results.
thank you BudMLeave a comment:
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Re: Samsung LN40B500P3F - Won't turn on
Just put the card back on and ran the tests.
First of all without the wire harness to the logic board on to check the VSB and then after.
VSB was 5.3V without anything on.
I Then connected the harness and put the TV back on. I was happily welcomed with hte turn on sound of the TV. Apparently the TV turn back on and does not stay on std by that first time.
So:
Voltage at the main caps on Std by : 176V
Voltage at the main caps with TV on : 386V
I have a...Last edited by veaux; 09-17-2014, 07:06 PM.Leave a comment:
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Re: Samsung LN40B500P3F - Won't turn on
With this box you pretty much put a bulb (the load) in serie with the TV which means that the voltage at TV will be less correct?
This box goes to the outlet and the tv is conected to the box right.
I'm curious (in the good way) to understand how this would affect the switching power supply in the TV if the TV gets a portion of the voltage it's expecting.
Do you happen to have a post somewhere in the forum explaining the why's? As mentioned earlier, I love to learn new things. Thank you.Leave a comment:
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Re: Samsung LN40B500P3F - Won't turn on
Ok, let me ensure I got that correctly:
1- put back the card in the tv as is (without Mosfets so the backlight will not work... I soldered the caps back in btw)
2 - put back a fuse
3 - connect the wire harness that goes to the signal card
4 - connect the tv to the outlet. At that point TV shroud be in std by with stdby led on
5 - measure voltage at capacitors CP815/CP816. Shroud be 170VDC
6 - turn on tv with remote.
7 - measure voltage at capacitors CP815/CP816. Shroud be >360VDC
...Leave a comment:
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Re: Samsung LN40B500P3F - Won't turn on
Can I so that without the new mosfets in ? I remember the 2 big caps at 170ish volts when the fuse was blown. What is the cap # you are talking about in the primary ?Leave a comment:
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Re: Samsung LN40B500P3F - Won't turn on
There you go. All is in OHMS unless noted otherwise.
RI870= 69
RI871=57.1
RI872=30k
RI873 / RI874= 237
RI875 = 68.5
Ri876 = 56.5
RI877 = 30k
RI878/RI879 = 237
At the transistors QI 874 and QI811 I get the resistance values of surrounding resistors.
On the diodes DI 830/831 and DI832/833 I also get the readings of the resistor, not sure how to test those.
At CI892, I get no reading, infinite resistance or at least more that...Leave a comment:
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Re: Samsung LN40B500P3F - Won't turn on
Those? Can I do it in circuit?...Leave a comment:
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Re: Samsung LN40B500P3F - Won't turn on
And yes. All measurements off the board. I got some trouble getting them out but I finally managed to do it after rocking them a lot....Leave a comment:
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Re: Samsung LN40B500P3F - Won't turn on
All in ohms. I had my DMM in the 200ohms position.Leave a comment:
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Re: Samsung LN40B500P3F - Won't turn on
Mosfets "resistance":
G-D-S Looking in front. Red terminal on the left pair in each test:
1)
G-D: 1.6
D-G: 1.6
G-S: 1.4
S-G: 1.4
D-S: 0.7
S-D: 0.7
2)
G-D: 1.5
D-G: 1.5
G-S: 1.4
S-G: 1.4
D-S: 0.7
S-D: 0.8
Now there is no more short between the 2nd pole of the fuse and teh common ground.
I'll put back the two condensators. Those have no polarity right.
Thx a lot I'll post back when I'll...Last edited by veaux; 09-16-2014, 04:48 PM.Leave a comment:
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Re: Samsung LN40B500P3F - Won't turn on
Alright. I'll look for a replacement for FDPF7N50U. Apparently they are obsolete. FDPF8N50NZU is a replacement per Mouser Electronics webpage. Any recomendation?Leave a comment:
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