LG UBK90 4K Blu-Ray no power

[luke9511]

hey everyone, i picked up a LG UBK90 4K Blu-Ray player for free off of facebook market place and the issue is that it does not power on, i have verified that there is power at the plug on the power supply and that the fuse is good

however it will not turn on, i started probing around trying to find the issue but i only have a basic multimeter right now and i am looking for some insight

Can anyone here help me confirm if this diode I am looking at is bad, I don't have my good meter but according to a fluke article, it should be between 1000 ohms and 10 miliohms, if it reads the same both ways it's bad, when I test it it goes up to over 5000 ohms no matter which way I have the leads and then it goes down to 0

my question is, is it good or is it bad? i can get the part number if need be

[luke9511]

Re: LG UBK90 4K Blu-Ray no power

i have tested the diode and it tests fine however test the STF8N80K5 mosfet is giving me some odd results, but it would seem from the different data sheets and videos and other websites that the mosfet is dead, is there one i can replace it with that is a little easier to find? i know i could use digikey or mouser but those will charge a lot on shipping when i only need one

EDIT: stupid me forgot the part number it is 8N80K5

[sam_sam_sam]

Re: LG UBK90 4K Blu-Ray no power

Unfortunately shipping costs have skyrocketed in the last few years what I do is order a few things that I know I can use and use USPS priority mail when I use Dig key when you order from them if you ask what is the cheapest shipping cost they will tell you

[luke9511]

Re: LG UBK90 4K Blu-Ray no power

Unfortunately shipping costs have skyrocketed in the last few years what I do is order a few things that I know I can use and use USPS priority mail when I use Dig key when you order from them if you ask what is the cheapest shipping cost they will tell you

the part is $2.00 and cheapest shipping is $9.99

[momaka]

Re: LG UBK90 4K Blu-Ray no power

Could you post a picture of the main board(s) and power supply of this player?

LG and Samsung regularly use their own SamWha, Sam Young, and other not-so-great (but not completely terrible) electrolytic capacitors, which tend to work OK for a while and then fail after a number of years.

Since you have no power, my suspicion would be the power supply. If the output electrolytic caps look OK, then the next suspect is usually the small "startup" electrolytic cap on the primary side (usually a 10-47 uF cap, rated for 25V, 50V, or 100V). When it goes bad, PSU cannot start up.

Easiest way to check if it's a cap issue (so long as the caps are not too far gone) is to open the unit and use a hair dryer to heat up the boards inside. Start with the power supply board and heat it up until everything inside feels nice and warm (but not burning hot) to the touch. Then plug in the unit and see if it powers up. If it doesn't, it could be that the caps have gone a little past "marginal", or there could be an issue somewhere else.

Either way, start with the hair drier and then let us know what happens. Then we continue from there. I don't suggest to "blindly" replace the MOSFET on the primary side (or any other parts) without verifying something actually is blown or bad. In the case of the MOSFET, for example, there is usually a low-resistance fusible resistor connected to its Source pin and primary-side ground (negative lead of the big electrolytic cap.) If the MOSFET goes bad, either that resistor will go open-circuit or the fuse would have blown. With your fuse being OK, I suspect the MOSFET in the PSU is still OK and the fault is somewhere else.

[luke9511]

Re: LG UBK90 4K Blu-Ray no power

Could you post a picture of the main board(s) and power supply of this player?

LG and Samsung regularly use their own SamWha, Sam Young, and other not-so-great (but not completely terrible) electrolytic capacitors, which tend to work OK for a while and then fail after a number of years.

Since you have no power, my suspicion would be the power supply. If the output electrolytic caps look OK, then the next suspect is usually the small "startup" electrolytic cap on the primary side (usually a 10-47 uF cap, rated for 25V, 50V, or 100V). When it goes bad, PSU cannot start up.

Easiest way to check if it's a cap issue (so long as the caps are not too far gone) is to open the unit and use a hair dryer to heat up the boards inside. Start with the power supply board and heat it up until everything inside feels nice and warm (but not burning hot) to the touch. Then plug in the unit and see if it powers up. If it doesn't, it could be that the caps have gone a little past "marginal", or there could be an issue somewhere else.

Either way, start with the hair drier and then let us know what happens. Then we continue from there. I don't suggest to "blindly" replace the MOSFET on the primary side (or any other parts) without verifying something actually is blown or bad. In the case of the MOSFET, for example, there is usually a low-resistance fusible resistor connected to its Source pin and primary-side ground (negative lead of the big electrolytic cap.) If the MOSFET goes bad, either that resistor will go open-circuit or the fuse would have blown. With your fuse being OK, I suspect the MOSFET in the PSU is still OK and the fault is somewhere else.

all the caps look fine, the power supply board has a date of 2019-04-08 the only thing so far that hasnt tested right has been the mosfet, i currently dont have my esr meter with me so i cant test the caps

[luke9511]

Re: LG UBK90 4K Blu-Ray no power

there is no edit button and i hate to do a reply, but i just did the air dryer method and it works! so you were right, its a cap, but the question is which one, i guess best bet would be to replace all 5 of them just incase to keep this from happening again in the future

EDIT i have started pricing out the replacement caps and the only one i am having an issue finding is a 47uf 460v cap

[momaka]

Re: LG UBK90 4K Blu-Ray no power

No worries about double- or tripple-posting. So long as you're adding information to a thread and not just doing it to get a higher post count or just bump a thread, it's fine (and even if you're not, hardly anyone cares. )

Great to hear the PSU sprung to life with the hair dryer heat.

Most likely, the cap you have to replace is that small electrolytic one close to the "WARNING" text. Though it probably also won't hurt if you replace the output caps too (the ones in the upper-left corner on the PSU board in the picture you posted above.) The large electrolytic cap on the primary side (CE101) rarely fails in these types of PSUs... but may be worthwhile to investigate too. In particular, if you see any crud or green corrosion near the leads coming out of its bung, consider it a candidate for a replacement too. It very rarely happens, but just had to note it here.

On the other hand, the heat from the hair dryer could have temporarily mended a cracked solder joint. So the issue may not necessarily be the caps (though it usually it is.) With that said, perhaps it may also be useful to post a picture of the under-side (solder side) of the PSU board you posted above. I doubt the issue would be bad solder joints, but still worth checking.

Lastly, if replacing the capacitors, make sure to use proper low-ESR ones, and preferably Japanese capacitors from a known reputable distributor like Digikey or Mouser (for those of us ordering in the US anyways.)
If you can, look up the brand, series, and info (capacitance & voltage rating) of the old caps. Then see which low ESR replacements from the Japanese brands fits your caps the closest.

For the most part, here are some known Japanese brands and the series listed that are known to be low ESR type and good fit for PSU use:
Rubycon YXJ, YXH, YXF, ZLJ, ZLQ, ZLS, ZL
Nichicon PS, PM, PW, HE, HD, HW, HV
United Chemicon LXV, LXY, LXZ, KYA, KYB, KY, KZE, KZH
Panasonic FC, FM, FR, FS

[luke9511]

Re: LG UBK90 4K Blu-Ray no power

No worries about double- or tripple-posting. So long as you're adding information to a thread and not just doing it to get a higher post count or just bump a thread, it's fine (and even if you're not, hardly anyone cares. )

Great to hear the PSU sprung to life with the hair dryer heat.

Most likely, the cap you have to replace is that small electrolytic one close to the "WARNING" text. Though it probably also won't hurt if you replace the output caps too (the ones in the upper-left corner on the PSU board in the picture you posted above.) The large electrolytic cap on the primary side (CE101) rarely fails in these types of PSUs... but may be worthwhile to investigate too. In particular, if you see any crud or green corrosion near the leads coming out of its bung, consider it a candidate for a replacement too. It very rarely happens, but just had to note it here.

i plan to just replace all of them but i just cant find a replacement for the big one in 460v max i can find is 450v and even then the best i can do is nichicon and the others are rubycon

[momaka]

Re: LG UBK90 4K Blu-Ray no power

i plan to just replace all of them but i just cant find a replacement for the big one in 460v max i can find is 450v and even then the best i can do is nichicon and the others are rubycon

460V? Are you sure?
Should be a 450V cap. 460V is not a standard voltage rating.

There's no APFC circuit in this power supply, so you can use even 420V or 400V -rated primary cap without issues. (Actually, since you're in the USA and we have 120V AC line, you can get away even with just a 200V -rated cap... just don't bring this overseas somewhere with 220-240V AC. ).

BTW, I did a small edit on my post above.

[luke9511]

Re: LG UBK90 4K Blu-Ray no power

460V? Are you sure?
Should be a 450V cap. 460V is not a standard voltage rating.

There's no APFC circuit in this power supply, so you can use even 420V or 400V -rated primary cap without issues. (Actually, since you're in the USA and we have 120V AC line, you can get away even with just a 200V -rated cap... just don't bring this overseas somewhere with 220-240V AC. ).

BTW, I did a small edit on my post above.

i thought it was weird as well and i double checked and scrapped away the glue that was on it and it says 47uf 460v, i am also attaching a screenshot of what i have added to my digikey cart to replace the caps with

i did check for bad and cracked solder joints and they all look good, though when i replace the caps i will give them a once over with my iron just to be safe

[momaka]

Re: LG UBK90 4K Blu-Ray no power

i thought it was weird as well and i double checked and scrapped away the glue that was on it and it says 47uf 460v,

LOL. Just curious, what brand and series is the capacitor? Maybe it's such an obscure brand that it has a printed typo.

i am also attaching a screenshot of what i have added to my digikey cart to replace the caps with

Looks good to me.

[luke9511]

Re: LG UBK90 4K Blu-Ray no power

LOL. Just curious, what brand and series is the capacitor? Maybe it's such an obscure brand that it has a printed typo.


Looks good to me.

i dont know the series but they are all chang or something like that and i will go ahead and get those ordered and get this thing fixed

[luke9511]

Re: LG UBK90 4K Blu-Ray no power

new caps arrived, took me about 10 or so minutes to replace them all, i did remove a pad by accident as you can see the green wire, but i managed to fix it and it tested fine and i added some hot glue to the cap on that side to keep it from moving

thanks for all of the help and advice and heres hoping this thing lasts a lot longer

[sam_sam_sam]

Re: LG UBK90 4K Blu-Ray no power

Another way to do this is if there is enough of trace is left you can take the lead from the capacitor to the trace and make it look a little neater but if you have to go over another trace just use some insulation from a wire and put it on the capacitor lead once you have the capacitor mounted just be careful to not use too much heat soldering to the trace

I have done this many times in the past and very good results

[thewolfe]

Re: LG UBK90 4K Blu-Ray no power

I created an account to post that I have the exact same Blu-Ray player, with the same issue. It died around 12/2021. All the caps look fine.

For anyone that may stumble upon this, as I did, the capacitors are all Chang. They can be looked up at:




Although, as mentioned, the 47uF 460v cap isn't listed on the sheets (or anywhere for that matter).

In circuit, the optocoupler is giving strange readings, but I'm going to start with the adjacent 47uF 50v cap. I'll probably do as you did and replace all the caps.

[momaka]

Re: LG UBK90 4K Blu-Ray no power

I created an account to post that I have the exact same Blu-Ray player, with the same issue. It died around 12/2021. All the caps look fine.

For anyone that may stumble upon this, as I did, the capacitors are all Chang. They can be looked up at:




Although, as mentioned, the 47uF 460v cap isn't listed on the sheets (or anywhere for that matter).

Hey there and welcome to BCN!
Thanks for chiming in to share those datasheets.

Wow, these things sure don't seem to last very long past the warranty (in EU land, there's a mandatory 2-year warranty, so I guess LG made these just to be able to "comply" to all markets.)

Yes, you won't see a 460V cap listed in any regular modern electrolytic datasheet, because it's not a standard value. Again, my hunch is someone made a typo at the factory for these "amazing" Chang caps and put 460V instead of 450V. What's more silly is that even a 450V cap would not be needed here, because the power supply does not have an APFC circuit. So that means 400V and 420V caps would be perfectly fine to use as replacements (and would likely be a little cheaper due to lower voltage and smaller size.) In fact, for those living in countries/places with 115/120V AC (North America & Japan, to name a few), even a 250V or 200V cap would be perfectly acceptable.

Indeed a good idea to replace all of the caps if you intend to keep the unit working for a long time. While the big primary "460V" cap may not be as likely to fail, it's just one less thing to worry about. The startup and output caps are probably the ones that are the most likely to fail.

Anyways, let us know how your recap goes and hopefully it fixes your problem too. That would be a good confirmation that these LG players are failing due to the caps and not something else.

[thewolfe]

Re: LG UBK90 4K Blu-Ray no power

I missed one datasheet (smallest cap):



Huawei (Chang) has a nice "Search by parameter" option as well for all their products:

http://www.huaweiec.cn/en/product/param

I went with all Panasonic caps, and ordered:

EEU-FR1H470B - 47uF, 50V, 6.3mm x 11.2mm
EEU-FM1C102 - 1000uF, 16V, 10mm x 20mm - x2
ECE-A1CKS470B - 47uF, 16V, 6.3mm x 5mm
EEU-ED2G470 - 47uF, 400V, 16mm x 25mm - Same dimensions as the Chang "460"

I also went ahead and ordered a board matching optocoupler and mosfet:

LTV-817B
STF8N80K5

I started by replacing the caps (in the order listed above), testing after each one with power to determine which cap was at fault. After replacing all 5 caps the problem persisted. I tested each cap out of circuit and they all appear to be fine. I really need to just get an ESR meter.

Next, I replaced the optocoupler and mosfet, testing with power after each component. Still no power through the board. I tested both original components out of circuit and they tested fine. Though, the mosfet wouldn't show continuity after switching gate to drain - but, neither did the new replacement, perhaps it's my cheap multimeter.

So, at the end of the day, the board is still not working. Though, I did get more experience soldering, so that's nice.

[nomoresonys]

Re: LG UBK90 4K Blu-Ray no power

@thewolfe, did you try heating with hairdryer per Momaka's suggestion.

[R_J]

Re: LG UBK90 4K Blu-Ray no power

What is the number on IC101 and what is the dc voltage across CE102?