Re: Samsung BN44-00445C power supply issue
I did quite a bit of that, no luck. I did however go over the board again to check for bad joints. While doing some measurement I stumbled upon a strange behaviour.
When I put my multimeter on point 1 in the screenshot (VCC line on the standby powersupply) the set starts every time without fail. I remove the multimeter probe and it clicks a while before starting. Almost like I'm adding some impedance to the line.
[ATTACH]263145[/ATTACH]
Tomorrow i'll start checking some DC caps to see if I...
nicdev007
Member
Last Activity: 09-11-2022, 03:41 AM
Joined: 04-28-2022
Location: Grenoble
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Re: Samsung BN44-00445C power supply issue
From memory it is R2A20118 and the technical specification I found says VCC 24V, I suppose that is a maximum value.
Very strange behaviour as the set starts up again for no reason.
When it starts the relay sometimes clicks a few times (4 times) or it just starts up without any issue. When it does the set works perfectly. I measure VS at 217V and VA at 55V and the VCC for ICP801 at 17V. The PFC around 388V.
I think I either have a bad capacitor in one of the standby PSU circuits, or a dry solder joint...Leave a comment:
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Re: Samsung BN44-00445C power supply issue
Hello all,
a quick update. The set restarted yesterday and I could check the screen which had quite a good picture, but during testing different parts, after switching it off, I could not switch it back on again.
When switching it on with the remote or front panel button, I just hear a quick relay click and it stays in standby. I am busy checking the standby power supply voltages to continue the troubleshooting but any ideas from your experience is greatly appreciated.
Does anybody know what the VCC voltage on the PFC...Leave a comment:
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Re: Samsung BN44-00445C power supply issue
Correct, it is in better state than the board I repaired, so I used it but just for clarity ;-)...Leave a comment:
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Re: Samsung BN44-00445C power supply issue
Hello all,
Thank you again for your inputs to assist with this unit. I changed QQ801 (marking not clear) but it is the regulator transistor for the Vcc of ICP801 (PFC controller). It seems when the PFC blew up it also blew up QQ801, and the 2 zener diodes ZDP801 and ZDP802.
The set now starts up, I have to still do a full test later to see if all functions are working, but that is great progress.
For future readers and information seekers, I replaced the following to repair the PFC circuit:
F801S,QP802, QP804,...Leave a comment:
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Re: Samsung BN44-00445C power supply issue
Thanks R_J for the valuable assistance,
Traced it back as you suggested.
Voltage across CM801 is a bit lower (17.5V). I removed QC802 (Vcc regulator) from the board to be sure and it measures faulty. I checked the other components in the circuit including the Zener and the rest measures ok.
I'll see if I have an equivalent tomorrow and if it will start up correctly. From what I have found the marking on the transistor "YB" is a KTD1624 (EPITAXIAL PLANAR NPN TRANSISTOR package SOT-89 package)....Leave a comment:
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Re: Samsung BN44-00445C power supply issue
Thanks for the advice, I have done so, but will go through it again and check if I missed some.
Regards
Nico...Leave a comment:
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Re: Samsung BN44-00445C power supply issue
Thank you, this is the schema I have also, but it does not correspond to the board unfortunately. ICP802 in this diagram is a 16 pin PFC driver (UCC28061), but on the board it is a 20 pin R2A20118 amongst many other differences. Some parts do correspond but not the part supplying Vcc to the PFC IC.
Regards
Nico...Leave a comment:
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Samsung BN44-00445C power supply issue
Hello all and thanks for the great welcome to the forum!
With the help of multiple community members and some of my own experience I have advanced on the repair of a Samsung PS59D530A5 TV. The power supply - PFC card number is BN44-00445C.
At first the PFC MOSFETS where blown along with a host of other SMD components including the PFC controller IC (20 pin R2A20118). I replaced all components found in a kit form, to be sure (F801S,QP802, QP804, DP802, QP806, QP808, QP805, QP807, RP815, RP806, DP804, DP807, RP803, RP807, RP804, RP808, ICP801). Attached a picture of the components... -
Re: New Members - please post your introductions here
Hello all,
I started in electronics in my uncle's TV repair shop aged 16, went on to become a Radio Engineer in aeronautics, and then into UPS systems engineer. I never lost the pleasure of repairing a TV or HiFi on component level. Today i repair a few units for friends and family mostly.
I am originally from South Africa, and live in France since 2007.
Best regards
NicoLeave a comment:
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