Philips 32pfs4132/12 LCD TV repair - Page 1
Forum section: electronics / repair

author: nForce
author_rank: Frequent Contributor
timestamp: August 25, 2019, 12:39:14 pm
content: Hello, I would like to know, what is wrong with my LCD Philips TV. When I turned it on, I heard a bang, and now I can't turn it on. The red indicator light is not showing. So because I heard a bang I thought to myself it must be a capacitor which blew up. So I opened it up and looked at the power supply board. See for yourself this power supply board:Here you can see that all capacitors are OK. I have measured all capacitors with the multimeter, and all capacitors are not conducting. So I have measured the resistors and one of them (marked with a green rectangle) which I think it's a 0.27-ohm resistor has a resistance of a few megaohms. So is this the problem? Why I can't see a black or brown spots on the resistor indicating that it blew up?With the visual inspection of the board, I can't see anything which blew up, because I heard a bang. Does anyone see a problem on the board (I am not an electronics engineer)?Thanks for the help.

author: Rasz
author_rank: Super Contributor
timestamp: August 25, 2019, 08:22:32 pm
content: have you checked fuse? could be the source of bang

author: pepona
author_rank: Contributor
timestamp: August 25, 2019, 10:55:22 pm
content: Hi, the problem is usually in the pwm controller located at the bottom of the board.We do not see this TV model in my country but we often repair this power supply in other Philips and Aoc models.In this link is the service manual.https://www.electronica-pt.com/esquema/func-fileinfo/64391/If you can download it and we can continue from there.Sorry for my bad English.RegardsMarcos.

author: nForce
author_rank: Frequent Contributor
timestamp: August 26, 2019, 07:56:28 pm
content: The fuse is conducting, so it's OK.pepona, I didn't know that you can get so much detailed description from a manual. What about the resistor in the green rectangle?

author: pepona
author_rank: Contributor
timestamp: August 27, 2019, 01:34:47 am
content: Hi, this resistor sense the current through the mosfet on the pimary side.Normally it's a low value resistor. If it measure in the MegaOhms range the mosfet is broken and may be the pwm controller too.I'm at home now, tomorrow at the workshop i'll see the service manual and i can help you with more precision.Excuse me for my bad English.RegardsMarcos.

author: pepona
author_rank: Contributor
timestamp: August 27, 2019, 10:59:02 am
content: Please download the service manual and have a look at page 44.Your resistor is R9101Please check: Q9101, R9109, D9104, R9110 and R9113.

author: nForce
author_rank: Frequent Contributor
timestamp: August 28, 2019, 06:42:03 pm
content: Thanks pepona. I will check it.

author: nForce
author_rank: Frequent Contributor
timestamp: August 29, 2019, 06:49:08 pm
content: Hey pepona, why does this resistor don't have a wattage rating? Does this mean we can replace it with 0.25 W or 5 W. It does not matter?

author: pepona
author_rank: Contributor
timestamp: August 29, 2019, 07:53:38 pm
content: Hi nForce, this resistor is usually 2w carbon or metal film. NEVER put an inductive one. Just to make a test you can put a 0.25w one.Remember to check the other components that i have marked to you.If you only change the resistor it will blow up again.RegardsMarcos.

author: Rasz
author_rank: Super Contributor
timestamp: August 30, 2019, 12:16:00 am
content: Quote from: nForce on August 29, 2019, 06:49:08 pmwhat do you mean? its right there on the attached picture, 2W

author: nForce
author_rank: Frequent Contributor
timestamp: September 01, 2019, 07:48:54 pm
content: Sorry, I was looking at the wrong resistor.What is Q9101? A transistor, is this our PWM controller?

author: Mario87
author_rank: Frequent Contributor
timestamp: September 02, 2019, 01:17:52 pm
content: Q9101 is the TK6A65D N-Channel MOSFET shown at the top of your picture in your original post, screwed onto the heat sink. Quite likely that MOSFET is responsible for the PWM.

author: nForce
author_rank: Frequent Contributor
timestamp: September 05, 2019, 06:49:39 pm
content: Thanks, guys.How can I check the MOSFET if it's defected? Some at the local repair shop has said to me, that I need to replace the whole power supply board, because of the lightning strike. But I don't see any marks on the board which would result from a lightning strike. Is this really the case? The fuse is OK and capacitors are also fine.

author: Rasz
author_rank: Super Contributor
timestamp: September 06, 2019, 02:41:59 am
content: mosfets go short most of the time, just buzz everything on this pcb for shorts

author: Mario87
author_rank: Frequent Contributor
timestamp: September 06, 2019, 06:56:45 am
content: Quote from: nForce on September 05, 2019, 06:49:39 pmFirst of all 99% of repair shops don't actually repair anything, they just swap entire boards to get things working.Next, as mentioned above, when MOSFETs fail, they generally fail short circuit between the source and the drain. You can see in your picture that the source is the pin closest to the bottom with the letter 'S' next to it and the drain is the middle one with the letter 'D' next to it. Check them with a multimeter, if they are shorted out, then you have a failed MOSFET.You will not always see external damage to a blown MOSFET. We had one at work on a new power supply module we have developed for our new product line and due to being a first fail in a new product we went to the extent of x-ray, decapping and microsection. X-ray showed nothing due to internal shielding, the decapping revealed physical damage to the die of the MOSFET and the microsection confirmed failure between the Drain and Source due to an over-voltage event, which is quite interesting as they are rated for 400V and we only use them for 24V switching....that's still being investigated.However, what I am getting at is that you might have failure of the MOSFET even though externally it looks fine. Check for a short between Drain and Source, then depending on what you come back with, see what the next steps would be.

author: pepona
author_rank: Contributor
timestamp: September 06, 2019, 05:29:21 pm
content: Hi everyone,nForce, you must first confirm if you downloaded the service manual, because there are the same power supplies with different PWM controllers.I just repaired one in the workshop and it is not worth buying a new one because the parts are very cheap.Could you confirm if the PWM controller is 6 or 8 pins?. Please upload a picture.In most cases, just change the MOSFET, some resistors and the PWM controller.And yes ..... these power supplies are very fragile against a discharge.Excuse me for my bad EnglishRegardsMarcos.

author: nForce
author_rank: Frequent Contributor
timestamp: September 06, 2019, 07:30:30 pm
content: pepona, your English is good, even better than mine.Yes, I have downloaded the service manual. But I don't understand in your first post you said that the PWM controller is located at the bottom of the board. Which one is exactly? I don't see it. At the bottom is one massive heatsink with diodes in reverse. It looks like two transistors, but they are actually not. Is the PWM controller not in the photo?

author: pepona
author_rank: Contributor
timestamp: September 06, 2019, 07:45:32 pm
content: The PWM controller is on the solder side. Just "behind" the MOSFET.

author: nForce
author_rank: Frequent Contributor
timestamp: September 06, 2019, 08:49:28 pm
content: Quote from: pepona on September 06, 2019, 07:45:32 pmOh, now I understand.Another question: Did I check the fuse in the right way, so I did not remove it from the board, but checked the continuity of the fuse on the board?Tomorrow I will upload the photo of the PWM controller.Thanks, this forum is great.

author: pepona
author_rank: Contributor
timestamp: September 06, 2019, 09:34:39 pm
content: Yes, if the fuse "beeps" it's ok.

author: nForce
author_rank: Frequent Contributor
timestamp: September 08, 2019, 04:41:41 pm
content: Hello, sorry for my slow response.Here is the photo of U9101, so this is our PWM controller. But it's 6 pin chip. Where can I get one? I was looking at the e-bay for PF6005AS, but I found only 8 pin chips.How can I check a diode if it's defected?I have checked all the elements, but the resistor R9113 which was supposed to be 1K is 0.658K. Is that OK? In the datasheet, it has no tolerance.I would like to ask pepona, how do you know that the problem is in this PWM controller? It can be anything on this board.

author: pepona
author_rank: Contributor
timestamp: September 08, 2019, 05:56:38 pm
content: Hi nForce, the pwm driver is "PF6005AG". I replace it with "PF6003AG" which has more driver capabilities.It may be that R9113 is less than 1k because it is soldered.The best practice to test diodes and resistors is simply to desolder them.To verify the pwm controller, the correct and safe way is to use an oscilloscope + differential probe and a variAC.If I don't have the right tools and I see that the R9101 has blown, it is certain that Q9101 is short-circuited or leaking.First, I check the components connected between the Q9101 gate and the U9101 pwm controller: Check R9109, 9110, 9111 and D9104.Then I check R9113 which is the one that connects R9101 and the CS (Current Sense) pin of the pwm controller.I also take a look at D9105 and D9106.If everything measures well, replace the PWM controller and damaged components.If you do not have a variAC you can replace the fuse with an incandecent lamp. It is not the best but if you have a short circuit nothing will explode in your face.In these smps the fuse never blowsSometimes the U9102 (optocoupler) and U9103 (TL431) blowns.I hope you understand me.I don't know what is worse: the google translator or me

author: nForce
author_rank: Frequent Contributor
timestamp: September 08, 2019, 07:01:59 pm
content: pepona are thesehttps://www.ebay.com/itm/5pcs-PF6003AG-6003A-PF6003A-SOT23-6-NEW/392410252043?hash=item5b5d79430b:g:-2MAAOSwbWhdbgWbcorrect? These have 6 pins.

author: pepona
author_rank: Contributor
timestamp: September 09, 2019, 01:48:42 am
content: Looks good to me

author: nForce
author_rank: Frequent Contributor
timestamp: September 09, 2019, 07:41:35 pm
content: What does mean only 6003A or PF6003A? Are these different names for PF6003AG?

author: pepona
author_rank: Contributor
timestamp: September 09, 2019, 08:14:25 pm
content: It´s just the marking code. "PF" means Power Forest.

author: nForce
author_rank: Frequent Contributor
timestamp: October 01, 2019, 03:54:39 pm
content: Hello, I have one beginner's question.Why do I have to remove the diode from the circuit to test if it's OK?Thanks.

author: Unknown
author_rank: Unknown
timestamp: November 21, 2019, 02:44:48 pm
content: Quote from: nForce on August 25, 2019, 12:39:14 pmHey, nForce did you fix your power supply?It seems I have that same resistor problem, but only I can see black marks of it, so it seems more likely thats the problem.

author: nForce
author_rank: Frequent Contributor
timestamp: January 04, 2020, 12:49:49 pm
content: Hello, I did not saw your post before. Did you fix it? So you only change the resistor, or you had changed some other components?

author: Dacke
author_rank: Regular Contributor
timestamp: January 04, 2020, 07:01:53 pm
content: Quote from: lok on November 21, 2019, 02:44:48 pmOn your board with the burned resistor if you look closely at the mosfet above it there is a burn spot between the source and drain pins, this is likely where it arced or shorted, possibly from dust buildup/debris on the bottom of the mosfet package. This, in turn, blew out the current sense resistor (the one that is burned) which is a low value and just acted as a fuse at that point. Newer TVs will generally have RTV over the legs of switching fets and PFC fets in an attempt to prevent this, but cheaper TVs may not. There's possibly other damage as well (blown gate resistor, oscillator, safety caps nearby, etc.). It can be a bit of work but it's usually not very expensive to repair.

author: waltham1
author_rank: Newbie
timestamp: August 10, 2020, 05:26:34 pm
content: Apologies if bumping old threads is not correct on this forum.Just wanted to share that I appear to have had the exact same issue with my Philips 4132.See photos attached. I believe it is to do with this resistor as previous, mine is showing obvious wear signs after the small bang and death of the screen.Unsure whether to get it repaired, or whether money is better spent on a new unit. Experience or advice is much appreciated. I am no TV technician or electrician, so would be paying someone to fix it. Wonder if that would make sense financially? Is it an easy/cheap job?Many thanks.

author: Scooby
author_rank: Newbie
timestamp: July 20, 2021, 02:05:03 pm
content: Hi there,Sorry for digging this old topic, but I ran into the same problem.I changed all components: Q9101, R9101, C9126, U9101 (which I upgraded to PF6003AG according to Pepona's recommendation), D9104, R9109, R9110, R9111 and R9113.The TV worked fine again ... but only for a couple of hours, and then it happened again: a BANG, and a black screen again.Meanwhile I noticed that the Q9101 MOSFET ran very hot ... too hot because it burnt again.So there must be an excessive current draw somewhere, but I am unable to locate it.I changed again the whole bunch of components and did a quick test: I works again, but still Q9101 is getting very hot.Someone could give me a hint please ?I checked other components on the PSU (the electrolytic capacitors and the blue film capacitor). Their values seem ok, except for the big 82µF capacitor wich only has 76µF, but that's probably acceptable ?Thanks for you help.

author: Scooby
author_rank: Newbie
timestamp: October 04, 2021, 11:59:16 am
content: Hi again,I finally found out why my MOSFET was overheating.The problem was that I installed a counterfeit TK6A65D MOSFET, which I bought from AliExpress.On a genuine TK6A65D the RDS(on) restance is about 1 Ohm.On the counterfeit one, I measured 11.6 Ohm@100mA, 16.8 Ohm@500mA and even 40.8 Ohm@640mA !!After installing a genuine one, bought from a trusted seller, there's no heating issue anymore.The MOSFET temperature is stable at 53°C during operation

author: peterpepo
author_rank: Newbie
timestamp: October 08, 2021, 02:37:20 pm
content: Hi,I came across this thread, when searching for same problem. The power indicator is dead, no light.I've measured all the parts, as mentioned in this thread as follows:I don't know:Q9101 - no short between S and DSeems broken:R9101 - 9,13kR instead of 0,27RR9109 - 12MR instead of 10RC9126 - split in halfSeems fine:R9104 - 36KR (probably fine, since there are two in series), same for R9106, R9105, R9107R9110 - 46,7R (should be 47 - ok)R9113 - 0,998KR (should be 1K - ok)R9111 - 10KRDidn't measure:U9101 since I don't have a scope. Don't know D9105, D9106 - Do I need to desolder them?Do you think it is enough to swap what I am pretty sure is broken - R9101, R9109, C9126?Do i need to swap Q9101 even though there doesn't seem to be short between S and D? Do I need to swap U9101?Is there anything else I should measure to identify the issue?Are there any alternatives for TK6A65D and PF6005AS? There is no carrier for PF6005AS (except one, selling for 17€) and TK6A65D are pretty difficult to find too.I'm trying my best to diagnose before ordering anyting, parts are not very accessible here, and I have to order everything from internet.

author: bemipefe
author_rank: Newbie
timestamp: February 01, 2025, 03:30:35 pm
content: Hello guys,I experienced the same power failure for this LCD TV. The impacted components in was the same and I replaced as suggested these components:Q9101 (replaced with TK6A65D), R9101, C9126, U9101 (replaced with PF6003AG), D9104, R9109, R9110, R9111 and R9113However i have no output DC current in the external connector where I should measure 12 V.The Q9101 is not shorted and when the board is powered source and drain are connected.From the ground and R9146 I read 10-16 V but the value is not stable and it changes with the same sequence.What can I check to figure out what component is failing ?(NOTE: I don't have the complete schema but only what was posted as image in this thread)

author: justElectronicx
author_rank: Newbie
timestamp: March 09, 2025, 06:15:38 pm
content: Philips TV PSU 715G7734-P02-005-002H – PF6005AG & MOSFET Keep Failing After ReplacementHello everyone,I've been troubleshooting aPhilips TV power supply (Model: 715G7734-P02-005-002H), and after checking multiple forum posts and analyzing my circuit, I found that many others have faced the same issue.By referring to the PSU datasheet (Page 44) and inspecting my board, I identified theblown componentsand ordered replacements fromAliExpress. However, after replacing everything, theMOSFET (Q9101) and 0.27Ω / 2W resistor (R9101)keep failing on power-up.Components Replaced (Defective & Preventive Maintenance)After the first failure, I replaced the shorted components:✅U9101 (PF6005AG PWM IC)✅Q9101 (K6A65D MOSFET)✅F9901 (Fuse, though it was fine on the second attempt)✅D9104 (Diode)✅R9101 (0.27Ω / 2W Source resistor, keeps failing)✅R9109, R9110, R9111, R1113 (Other critical resistors in the circuit)✅C9126 (100pf Capacitor between Source to drain)Since theVCC voltage was fluctuating, I also replaced the following as a precaution:✅C9105 (10µF capacitor at startup circuit)✅D9106 (1N4148W Diode, between startup caps)Debugging & Voltage Measurements1️⃣Checked the startup resistors (R9101, R9102, R9103 - all 510KΩ).-Measured ~480KΩ on each, looks within tolerance.2️⃣Checked the entire startup circuit, all resistors & components tested OK.3️⃣Measured VCC voltage:-Without IC soldered: 47V (seems normal).-With IC soldered: Drops to 7.4V (suggesting an issue with startup or excess current draw).-Expected vcc voltage between 12V - 18V.4️⃣Soldered all other resistors and diodes again, but VCC remains 7.4V.5️⃣Tried soldering the MOSFET again, but it blew instantly (this time the main fuse remained intact).6️⃣Measured Auxiliary Power:-Got ~350V DC, which is correct.What Could Be Causing This?-IC not powering up correctly (VCC too low, could be internal failure or incorrect feedback loop).-Excessive current draw somewhere in the circuit(but no visible shorts apart from MOSFET failures).-Faulty transformer or snubber circuit(possible high-voltage spikes causing repeated MOSFET failures).-Incorrect gate drive signal(I don’t have proper tools to measure output frequency, so I can’t verify this).Next Steps / Need Advice- Could thetransformer be damaged and causing overcurrent issues?- Should I try adifferent brand of PF6005AG / MOSFETin case of a bad batch?- What other components should I check before attempting another replacement?Any suggestions or insights would be greatly appreciated! Thanks in advance.