Re: Philips 32PFL7562D TV
Thanks guys for the responses -- will consider the hints when it becomes faulty again.
Pauldesign
Member
Last Activity: 01-26-2019, 11:45 AM
Joined: 04-11-2013
Location: Joburg
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Philips 32PFL7562D TV
Hi Folks,
I've got this Philips 32PFL7562D 32" TV screen that behave funnily -- either by design or faulty somehow?
It works well for about 3 months then suddenly stops working for about a month then again start working again well...
The symptom is, when it becomes faulty, it instantly goes to standby (from blue light to orange) when i switch-on and that's it -- i've checked to no avail?
I've attached pictures of the PSU (very big/old and awkward to troubleshoot) -- some repairs where done on the PSU before and seems a bit doggy.... -
Re: Help with Toshiba 32av502r power supply
When ever a fuse blows, it highly possible that it dies with the bridge rectifier (shorted), the short circuit resistor protection (blown), the switching MOSFET as well as the PWM IC driving the MOSFET -- check for shorts using diode or resistance test of your multimeter.Leave a comment:
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Re: Samsung SyncMaster 2493HM black screen with power no sound
Just search on the forum using 'Samsung 2493HM' as keywords, you'll see tons of advice that have been offered before on that screen as well as the PSU-- please, endeavour to go through all the threads and suggestions, as there is really nothing new to add, besides first making use of all the existing knowledge in the forum.
You may then update the forum of your efforts so far and you may be assisted should your issue is unique / new; otherwise, what will be offered will just be repetition of possible solutions...Leave a comment:
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Re: TV keeps blowing fuses !
Sorry Budm -- i just saw your post now with the labelled PSU after cross posting (due to different time zones) my findings.
Nevertheless, thanks for the follow-up and i hope my explanations suffice your request.Leave a comment:
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Re: TV keeps blowing fuses !
Well, after more testings, the instant short was due to a faulty PFC rectifier diode, that had it's cathode shorted to its metal tab and since the tab was connected to the heatsink and subsequently to the AC hot-side ground; the output from the PFC transformer which is connected to the drain of the PFC MOSFET as well as to the anode of the PFC diode, was instantly shorted to ground once the PFC diode conducts on switch-ON, hence the big bang !
The reason i couldn't find the issue until after applying intuitive troubleshooting by disconnecting...Leave a comment:
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Re: TV keeps blowing fuses !
@Budm, without schematic is difficult to refer to such parts. But I think, I found the cause of the severe short and I'll finally confirm on Monday after more conclusive tests. I only hope other components didn't blew as well.Leave a comment:
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Re: TV keeps blowing fuses !
Thanks gents for all the hints.
What I realised is when the primary MOSFET is removed, it doesn't pop fuse (in essence, when the secondary (about 700V) of the primary inductor is disconnected from the rest of the circuit) , however, when the primary inductor output is connected back (withour the MOSFET) and only to the diode which is normally in series with the drain of the primary MOSFET, which are together disconnected from the rest of the circuit, it pops the fuse.
Running out of fuses, I'll try all the hints at once and...Leave a comment:
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TV keeps blowing fuses !
Hi Folks,
I've this Telefunken TV with power board labeled F-3445 Sun6132 that just keep blowing fuses instantly.
I've done the following to no avail:
- Check for shorts between live and neutral as well as ground.
- Check for shorts across the main rectifier / filter caps.
- Check for short in the bridge rectifier.
- Check for shorts in the MOSFETs
- Check for unintentional shorts in the ICs
- Check for shorts in the feedback circuitry.
- Check for shorts between the primary and secondary sides
- Check... -
Dell Inspiron Mini 1012 laptop: no backlight
Hi Folks,
I have a Dell inspiron mini 1012 laptop but there is no back light, although i can see the user interface fainthly in the background. The back light comes ON instantly when switch ON and goes OFF (so-called 2s to black). The laptop works well with an external display.
I've opened it and tested the LED back light to be OK (by testing all the LEDs and all lighted-up). The logic board fuses all tested OK and I've measured the voltages as well as the one directly at the back light connector and it reads ~15V and stable but the backlight doesn't still turn on.... -
Re: Samsung 24" power supply BN44-00195A first stage voltage?
Can you measure the voltages and are they there or stable -- i reckon you check the main filter cap.Leave a comment:
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Re: Samsung 2493HM (PSU:BN44-00195A): No 24V 5.4V Drama
Thanks Budm.
I'll do more measurements and with better test equipment and update you.
Is just that the PFC IC isn't readily available in my area and is a bit pricey; otherwise, i could've done a replacement and see the outcome, although the current process is a good learning curves which is the right way to go first.Leave a comment:
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Re: Samsung 2493HM (PSU:BN44-00195A): No 24V 5.4V Drama
Well, from probing more with ICM801S disconnected from the circuit by cutting off PFC and M_Vcc supplies to that sections of the circuitry, i realized the following:
- The voltage across the big cap exceeds 300V, although i still need to measure the exact value.
- When diode DP802 is removed, the big cap voltage reads ~300V as well as the drain voltage and the repetitive ON/OFF switching click noise stops and furthermore, there is stable ~11V3 drive voltage from Pin 7 of ICP801S (TDA4863) to the gate of...Leave a comment:
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Re: Samsung 2493HM (PSU:BN44-00195A): No 24V 5.4V Drama
Thanks Budm for your continuous and quick responses.
Yes, we do have the same boards and I can measure stable 14v on ICM801S Vcc pin. Unfortunately my current toy multimeter can only measure up to 300v and complains if more which can give me an idea if PFC is OK, although not ideal. I'll probe more and update you.Leave a comment:
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Re: Samsung 2493HM (PSU:BN44-00195A): No 24V 5.4V Drama
Thanks Budm for assisting.
I replaced the 15V zener (BZX84C15) with an equivalent as well as the series diode, which seems to do the trick, although the output voltage (M_Vcc) at the emitter is now ~14V; which is not exactly 15V but i supposed should suffice for now, considering the wide tolerable input voltage range.
Well, the problem now is the drive voltage from ICP801S (TDA4863G) into QP801S (i supposed yours is Q801S) seems to drop to about 2V and i can hear some ON and OFF switching noises...Leave a comment:
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Re: Samsung 2493HM (PSU:BN44-00195A): No 24V 5.4V Drama
Thanks budm for taking your time to assist.
There is no Q801/2 on the board/schematic -- i guess you're referring to QB801/2, just to avoid confusion.
Well, using the equivalent PSU BN44-00192B schematic as reference:
Since there is a 15V Zener diode (BZX84C15) at QB802 base, it means the base voltage can't exceed 15V, which means i can assumed a required base voltage of 10 to 14V.
Therefore, if the base voltage shouldn't exceed 15V, then the voltage at the emitter can't be...Leave a comment:
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Samsung 2493HM (PSU:BN44-00195A): No 24V 5.4V Drama
Hi All,
I've this Samsung 2493HM screen with PSU: BN44-00195A for a while now.
Well, i've read all the threads / responses on this model/PSU inside out and more than twice -- so, i've done all the necessary recommendations but to no avail.
The blue light is ON and the standby voltage (5V2) is OK as well as the PS_ON (3V3). However, there is no power to the inverter -- there is no 24V and 5V3.
Using equivalent PSU BN44-00192B schematic, I found the transistor QB802 faulty (i de-solder and measure the B-E to be 30 ohms either way which... -
Re: Hannspree HF257 - White Screen
I reckon you measure about 2 or 3 of the other parallel caps (de-solder one side of each) to accurately determine the identical faulty cap value, since measuring just one cap might not give you the right value due to tolerance / ageing.
Judging from the cap size, the faulty cap value will not be greater than 10uF. In the meantime, you may quickly connect a 10uF (check the polarity) cap as replacement and see if it helps.
RegardsLeave a comment:
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Re: Samsung 2493HM Power Board failure
The possible failed component(s) will be the following;
- The MOSFET as indicated -- any equivalent should work, double check both datasheets -- check for shorts
- The short circuit or current sense resistors -- usually less than an Ohm (0.2 to 0.4 ohm) -- check for open
- The PWM chip; check for shorts across pins
- Finally, surrounding resistors linking those components -- check for opens.Leave a comment:
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Re: How to troubleshoot a Samsung Syncmaster T220 that doesn't power up?
Flickering is as a result of the back lights trying to switch ON -- similar to your normal fluorescent lamp. The voltage across each in a pair might be different, which could be as a result of your PSU or the back lights could be weak.
If you take the back lights out or have spares, you'll notice what i mean, as you'll immediately see the difference in brightness intensity of the each tubes in a pair and if you measure the DC voltage across each, they'll surely be different.
From...Leave a comment:
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