Anyone have, or know where I can find a service manual for this TV?
Need a schematic for the power supply. Board number is BN44-00417A.
Fisher77
Badcaps Veteran
Last Activity: 11-21-2024, 09:15 AM
Joined: 02-17-2016
Location: Home of Texas Tech
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Samsung LN40C500F3FXZA
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Samsung PN58C550 Not Turning on
Bought this one on craigslist for 20 bones. TV would not turn on when I got it. I found the QP802 MOSFET blown and both the F801S, and the F802s blown. The FET is a 20N60C3 I replaced it and both fuses, turned on the TV, ran for about 5 minutes, and blew it again.
I have checked the components near the FET, and didnt find anything bad. The only component I am not sure of are the SOT23's that say B6 on them. Not sure what they are....Last edited by Fisher77; 01-13-2018, 08:32 PM. -
Re: Hitachi LE42H508
Well it blew 2 more LED's. I replaced both of them and the transformer is back to buzzing. -
Re: Hitachi LE42H508
Back together and has been on for most of the day. I turned the backlights down to 25.
I appreciate all the help budm....Leave a comment:
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Re: Hitachi LE42H508
Ebay. Who knows if the seller had the specs listed right.
I can get more if you have a good source for them.Leave a comment:
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Re: Hitachi LE42H508
Man I hope they are right. They were listed for Hitachi.
Forward Voltage - 3.0 - 3.6v
Forward current - 265mA
Pulsed Forward Current - 330mA
Power Dissipation - 1WLeave a comment:
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Re: Hitachi LE42H508
Ok budm, I replaced the LED's. They are all working agin with a power supply.
Before I put this back together, do I need to replace the Zeners, or is it good to go without them?Leave a comment:
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Re: Hitachi LE42H508
They have N2 on them, and a K turned sideways....Leave a comment:
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Re: Hitachi LE42H508
budm is there a good source for the LED's?
Any need to replace the Zener's?Leave a comment:
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Re: Hitachi LE42H508
Thanks budm.
I just tried them with a power supply. The ones without a blown LED light up just fine. The ones with a blown LED will not light up.Leave a comment:
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Re: Hitachi LE42H508
Ok budm. I measured all 8 of the little buggers off the boards.
5 of them read .0
2 of the read .1
1 of them read .2
all of those readings were in both directions.Leave a comment:
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Re: Hitachi LE42H508
With the Zener off it measures OL.Leave a comment:
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Re: Hitachi LE42H508
I tested the resistance on each strip.
4.7 ohms
3.8 ohms
37.5 ohms
51.6 ohms
235.1 ohms
138.3 ohms
13.9 ohms
137.8 ohms
I assume the 2 with less than 5 ohms are shorted?Leave a comment:
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Re: Hitachi LE42H508
I tested each led individually with diode mode on my multimeter. It lit them dimly, except for the blown ones of course.
After I replaced the two blown diodes on the PSU yesterday, the tv powered on with the backlights, but the transformer was squealing. After I took it apart, and put it back together, the LED's never lit again. It's weird. I looked at all the wiring, nothing was shorted.Leave a comment:
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Re: Hitachi LE42H508
Ok there is 40 LED's total.
There are 6 strings that have 1 blown LED each.
There is a Zener diode on each string, and they are all blown. I measured them in diode mode, is that the correct way to measure a Zener?
Question is what blew the Zener's?
Zeners have N2 on them, any idea what they are?
The LED's were working before I took the tv apart yesterday. I checked for anything shorted as I took it apart today, and did not find anything....Last edited by Fisher77; 12-13-2017, 11:42 AM.Leave a comment:
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Re: Hitachi LE42H508
Ok, I will get take it part, and see what I fine.Leave a comment:
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Re: Hitachi LE42H508
Your right budm, something is jikky.
When I ohmed from red to chassis GND last night it was 20k ohms. This morning is is reading OL. I tried 2 different meters, and they both read OL.
Ohming from the red to white wires I am getting .5k ohms. Don't know if that will tell you anything or not.
I checked the diode again, it was reading .5, so its good.
I didn't count the leds when I took it apart. I will take it apart again and see how many there are and report back.Last edited by Fisher77; 12-13-2017, 10:39 AM.Leave a comment:
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Re: Hitachi LE42H508
The voltage rating on the cap is 200vdc.
Yes it is still squealing even though the LED's are not coming on.
The voltage across the LED pins with the connector unplugged is 185vdc.Leave a comment:
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Re: Hitachi LE42H508
Ok, redid the solder joints on both diodes, and the transformer.
I used a 65W, and flux.
Voltage between red wire and chassis GND is 21.9vdc.
Voltage between white wire and chassis GND is 9.6vdc.Leave a comment:
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Re: Hitachi LE42H508
Here are the readings:
Between GND and the white wire is 21.18k
Between GND and the red wire is 20.81kLeave a comment:
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