LG 50PG30 Plasma TV PSU Capacitor Replacement

[nirvdrum]

I have four clearly blown capacitors (10V 3300 uF) on the PSU board for my LG 50PG30 plasma TV. If it helps any, the board is EAY43521401 (PSP-J703B). The TV was manufactured in 2008. They're all Samwha capacitors. I still like the visual quality of the TV, so I'm inclined to repair it.

Replacing the four blown capacitors is straightforward. Where I could use some guidance is whether to replace all the other electrolytic capacitors. I've seen conflicting recommendations: 1) replace them all and be done with it; or 2) only replace the ones most stressed, since the others are unlikely to fail. I don't have an ESR meter. Likewise, I don't have enough knowledge to trace back each capacitor and determine what it's used for.

I have gone through and identified all of the electrolytics on the PSU board. They're all 105C and I assume low ESR (I didn't actually track down data sheets for each). The sizes are probably off by a little (I used calipers and some are a bit awkward to get at). The list is:

Code: [Select]

Voltage (V)  Cap. (uF)     Pitch (mm)  Size (mm x mm)  Qty
   50          4.7              5            5 x 11     1
   50          10               5            5 x 11     1
   50          22               5            5 x 11     2
   50          33               5            6 x 11     2
   50          47               5           6.3 x 11    2
   100         47               5            10 x 16    1
   450         68              7.5          18 x 31.5   1
   16          100              5            5 x 11     2
   25          100              5           6.3 x 11    1
   250         220             7.5           18 x 30    3
   450         330             10            30 x 40    2
   10          470              5           8 x 11.5    1
   100         820             7.5           18 x 40    1
   10         1000              5            10 x 16    2
   25         1000              5            10 x 20    2
   10         3300              5           12.5 x 25   4

Hopefully, that's enough information to work off of. Unfortunately, I don't have a schematic for this board.

I've spent a lot of time tracking down part numbers for each, favoring Panasonic FRs and Nichicon. I don't know if mixing vendors is frowned upon, but in some cases I found one vendor had much better ESR ratings than the others. In other cases I just couldn't find a suitable part for that vendor. The next problem is some of these parts are difficult to source in such low quantities. In order to get the full set of capacitors, I need to buy from both Arrow and Digikey. I've looked at Arrow, Digikey, Mouser, and Newark and none of them have all the parts available.

I'm looking at ~$65 for all the capacitors, once shipping is worked in, with the bulk of the order going to Arrow. It's not the cheapest repair in the world, but if I can extend the life of the TV, I'm happy to do it. I am a little bit worried that I'm replacing parts unnecessarily. Beyond the cost savings (the larger capacitors are a few USD apiece), I don't want to introduce new problems by replacing items I shouldn't. I appreciate any feedback or guidance on the repair.

[PKTKS]

*SHOULD* be close enough for that..

in  RAR parts due to limits.. and 7z extension

Paul

[PKTKS]

p2

[PKTKS]

p3

[wraper]

Those bulged capacitors likely are Samwha WB which are bad series. If you replace all of WB, you can probably leave the rest as is. Note that WB is ultra low ESR series. You don't need to replace high voltage capacitors, usually they last much longer.

[drussell]

Replacing the four blown capacitors is straightforward. Where I could use some guidance is whether to replace all the other electrolytic capacitors. I've seen conflicting recommendations: 1) replace them all and be done with it; or 2) only replace the ones most stressed, since the others are unlikely to fail. I don't have an ESR meter. Likewise, I don't have enough knowledge to trace back each capacitor and determine what it's used for.

Generally the only ones that are really stressed in any way are the ones handling large pulses of relatively high current like in the outputs of switching supplies and regulators.  I would only replace any of the ones that are in those positions, you can probably spot some any of those areas just looking for switching transformers or power inductors.  These will be the ones that are low-ESR, high-ripple-capable types because they need those characteristics.  You can look up the datasheets for the couple different series that are likely in there and just replace the ones that are those series.

What was/is the symptoms / problems with the TV?  Did it simply stop turning on?  Was it becoming problematic before and then just failed?  There is a good chance that your issues are caused only by the capacitors that are obviously dead.  Probably the "easiest" and certainly least expensive would be to just replace the obviously toasted ones and see how the set works unless you have reason to suspect that more are failing / likely to fail. 

This brings you back to either being the same part type / series as the ones that failed and/or used in similar service in the circuitry and trying to decide if they're likely to go "bad". 

[RayRay]

If you wanna save up, I'd recommend you order the caps from lcsc.com (they have a great selection of rubycon/nichicon/panasonic /united chemi-con ones) at reasonable prices, and without having to purchase em in bulk (they also have multiple shipping options available, so you could save up there too, if you don't mind waiting a bit longer for em to arrive). As for your questions, things aren't always as they seem (and a cap be bad even if it looks okay physically) so if you can't test the capacitance & esr, it'd be best you'd have em all replaced to be on the safe side (with low esr ones of course) and no, there's absolutely no problem with mixing capacitors of different brands on the same circuit board. And remember, the key rule with capacitor replacement is having the same uF rating with the voltage being either equal or higher, so for example, for the 1000 uF ones, you could just have em replaced with 25v 1000uF (no need to purchasse 10v and 25v in separate!) Set the capacitors aside, I'd suggest you also test out the rectifier diodes (in both diode & ohms mode on your meter) as explained here:
https://www.eevblog.com/forum/repair/bosch-al1820cv-blowing-capacitors/msg3521746/#msg3521746
The diode testing function alone isn't compeltely reliable. Also, here's the service manual for that particular TV:
https://www.manualslib.com/manual/1200684/Lg-50pg30.html

[perieanuo]

normally somebody ( a pro) won't replace 100% of electrolytics present on pcb, only those supposed to die (near heat source, big challenge - riple for example)
but you can replace all if you want, personally i replace only the 'suspects of service', don't realise if it make sense in english

[RayRay]

normally somebody ( a pro) won't replace 100% of electrolytics present on pcb, only those supposed to die (near heat source, big challenge - riple for example)
but you can replace all if you want, personally i replace only the 'suspects of service', don't realise if it make sense in english

I disagree with what you're saying here. A pro wouldn't do repair work based on speculation (he'd test the capacitance & esr of all of em, outside the circuit, before deciding what needs to be replaced) but given the fact the OP doesn't have proper testing gear, I think he'd be best replacing all of em and not leaving anything to chance.

[wraper]

A pro wouldn't do repair work based on speculation (he'd test the capacitance & esr of all of em, outside the circuit, before deciding what needs to be replaced) but given the fact the OP doesn't have proper testing gear, I think he'd be best replacing all of em and not leaving anything to chance.

Pro won't do such time wasting exercise. No pro values their time so low to spend it on desoldering every capacitor just to put them back later. Not to say measuring ESR in circuit is enough in most cases.

[RayRay]

A pro wouldn't do repair work based on speculation (he'd test the capacitance & esr of all of em, outside the circuit, before deciding what needs to be replaced) but given the fact the OP doesn't have proper testing gear, I think he'd be best replacing all of em and not leaving anything to chance.

Pro won't do such time wasting exercise. No pro values their time so low to spend it on desoldering every capacitor just to put them back later. Not to say measuring ESR in circuit is enough in most cases.

We aren't talking about an excessively high number of capacitors here. Desoldering (with the right soldering station, technique and experience) isn't difficult, and yes, the ESR can be measured in circuit too (depending on the meter). Capacitance in some cases as well (if the cap isn't connected in series to another) and sometimes, desoldering one leg would suffice for taking a measurement. I still stand by my words, you can disagree if you wish, but my opinion is, when reparing, leave nothing to chance, and test everything accordingly. And again, given the OP doesn't have the proper testing gear, it is my opinion that he'd be best replacing all of the caps.

[wraper]

A pro wouldn't do repair work based on speculation (he'd test the capacitance & esr of all of em, outside the circuit, before deciding what needs to be replaced) but given the fact the OP doesn't have proper testing gear, I think he'd be best replacing all of em and not leaving anything to chance.

Pro won't do such time wasting exercise. No pro values their time so low to spend it on desoldering every capacitor just to put them back later. Not to say measuring ESR in circuit is enough in most cases.

We aren't talking about an excessively high number of capacitors here. Desoldering (with the right soldering station, technique and experience) isn't difficult, and yes, the ESR can be measured in circuit too (depending on the meter). Capacitance in some cases as well (if the cap isn't connected in series to another) and sometimes, desoldering one leg would suffice for taking a measurement. I still stand by my words, you can disagree if you wish, but my opinion is, when reparing, leave nothing to chance, and test everything accordingly. And again, given the OP doesn't have the proper testing gear, it is my opinion that he'd be best replacing all of the caps.

"Only" 28 capacitors. Who will pay for the time spent? What about mechanical and thermal stress on the seals? If you take the effort of desoldering them, you just replace all of them. Also usually you cannot desolder one leg of electrolytic capacitor. And why don't you check every other part outside of the circuit and then assemble everything back? You don't want to take any chances after all.

[RayRay]

"Only" 28 capacitors. Who will pay for the time spent? What about mechanical and thermal stress on the seals? If you take the effort of desoldering them, you just replace all of them. Also usually you cannot desolder one leg of electrolytic capacitor. And why don't you check every other part outside of the circuit and then assemble everything back? You don't want to take any chances after all.

I think you're taking this a bit too personal. Overall, the OP was given two different approaches, and it's up to him which one he prefers to go with (and it's his time, not yours!) From one hand, it's possible that replacing only the bad ones & the higher capacitance ones alone would suffice, from the other, it's a gamble, which may not do the trick.  And yes, you can desolder one leg of a capacitor just fine (with a wick/pump, leaving it in the joint, but not connected).

[nirvdrum]

What was/is the symptoms / problems with the TV?  Did it simply stop turning on?  Was it becoming problematic before and then just failed?  There is a good chance that your issues are caused only by the capacitors that are obviously dead.  Probably the "easiest" and certainly least expensive would be to just replace the obviously toasted ones and see how the set works unless you have reason to suspect that more are failing / likely to fail. 

We had a brownout and afterwards the TV turned itself on and went into a power cycle loop. I had to disconnect the power cord to get it to stop. Fortunately, the TV doesn't remember power state on AC loss or anything like that, so if I plug it in, it remains off until I press the power button. Xut pressing the power button puts it into a power cycle loop: it turns on, shuts off about a second later, then turns itself back on, then off again, until I remove the power cord again.

When working before, the TV always took a little while before the screen started displaying something. I can't tell if it's a situation where it was just gradually getting slower over time. I'm curious to see if the capacitor replacement makes the TV turn on any faster. But, I was mostly thinking of replacing more than the obviously bad ones because it's a 12 year old plasma TV, so the caps have certainly had some heat exposure. $8 shipping for four capacitors kinda sucks, so I was trying to cut down on the back-and-forth.

Thanks for the other info. I'll read the datasheets for the various Samwha series.

[nirvdrum]

Those bulged capacitors likely are Samwha WB which are bad series. If you replace all of WB, you can probably leave the rest as is. Note that WB is ultra low ESR series. You don't need to replace high voltage capacitors, usually they last much longer.

Indeed, they are. There are some other WB caps on the board that don't have visible signs of failing, but I don't have an ESR meter. I'm debating whether to just order one at this point. Some of the caps are oriented in such away that I can't read the series identifier without removing the part. It looks like some are from the RD, PT, and WL series.

I'll go read up on the others. Obviously, the manufacturer isn't going to say some of their products are bad, so I appreciate sharing any experience. Likewise, I couldn't tell whether the 2008 manufacturing date was something to consider or not as well, given the problems with capacitors from earlier in that decade.

[nirvdrum]

*SHOULD* be close enough for that..

in  RAR parts due to limits.. and 7z extension

Thanks for sharing that. Unfortunately, the schematic labeled "POWER" doesn't appear to match the PSU board I have. Or, I'm reading it wrong (in this case the effect is the same).

[nirvdrum]

If you wanna save up, I'd recommend you order the caps from lcsc.com (they have a great selection of rubycon/nichicon/panasonic /united chemi-con ones) at reasonable prices, and without having to purchase em in bulk (they also have multiple shipping options available, so you could save up there too, if you don't mind waiting a bit longer for em to arrive).

Thanks for the recommendation. I had come across that site, but I couldn't determine how trustworthy it is. The last thing I want to do is unwittingly use counterfeit capacitors.

[gnuarm]

normally somebody ( a pro) won't replace 100% of electrolytics present on pcb, only those supposed to die (near heat source, big challenge - riple for example)
but you can replace all if you want, personally i replace only the 'suspects of service', don't realise if it make sense in english

I disagree with what you're saying here. A pro wouldn't do repair work based on speculation (he'd test the capacitance & esr of all of em, outside the circuit, before deciding what needs to be replaced) but given the fact the OP doesn't have proper testing gear, I think he'd be best replacing all of em and not leaving anything to chance.

That doesn't make sense to me.  Caps are rather inexpensive items.  Testing them out of circuit would cost as much as replacing them. 

[RayRay]

Thanks for the recommendation. I had come across that site, but I couldn't determine how trustworthy it is. The last thing I want to do is unwittingly use counterfeit capacitors.

You're very welcome. FYI, LCSC is a very reputable store (that's been around for a long time) and they're definitely trustworhy. I've personally ordered various components from em (incl capacitors) and I can assure you they don't sell counterfeits!

but I don't have an ESR meter. I'm debating whether to just order one at this point.

Well, getting one would certainly be useful, but would cost you way more than just replacing the caps, so if anything, I'd say it'd be a good investment for future repairs. Provided you already have a decent capacitance meter (or that functionality in your multimeter, with a decent range) you could get the MESR-100 for around $60. If you don't have any capacitance meter though, it'd prob be best to go with the DE-5000 or Atlas ESR70

[nirvdrum]

Well, getting one would certainly be useful, but would cost you way more than just replacing the caps, so if anything, I'd say it'd be a good investment for future repairs. Provided you already have a decent capacitance meter (or that functionality in your multimeter, with a decent range) you could get the MESR-100 for around $60. If you don't have any capacitance meter though, it'd prob be best to go with the DE-5000 or Atlas ESR70

Up until I started looking into this repair, I didn't even know ESR meters existed. If having one is good, I don't mind investing in equipment. I have a Proster BM4070 LCR meter that I picked up measure capacitance among other things, but it doesn't have ESR functionality. Beyond that, I have a Siglent SDM 3055 bench DMM and an older Radio Shack 22-174B hand-held DMM. I'll take a look at the ESR meters you mentioned.

[RayRay]

Up until I started looking into this repair, I didn't even know ESR meters existed. If having one is good, I don't mind investing in equipment. I have a Proster BM4070 LCR meter that I picked up measure capacitance among other things, but it doesn't have ESR functionality. Beyond that, I have a Siglent SDM 3055 bench DMM and an older Radio Shack 22-174B hand-held DMM. I'll take a look at the ESR meters you mentioned.

Having one is definitely very handy! Anyways, given the fact the capacitance range is a bit low on your LCR, I think it'd be best you'd go with a combo ESR/Cap meter (DE-5000/ESR70) rather than a standalone ESR one.

[nirvdrum]

Having one is definitely very handy! Anyways, given the fact the capacitance range is a bit low on your LCR, I think it'd be best you'd go with a combo ESR/Cap meter (DE-5000/ESR70) rather than a standalone ESR one.

I ended up getting the DE-5000. I was able to measure most caps in-circuit. A couple gave odd readings, but I haven't popped them off yet to isolate them. Two of the caps are Samwha PT series, but I can't locate any datasheets for those.

I ended up measuring dissipation @ 120Hz and ESR @ 100kHz in-circuit for all the caps (~21°C). Other than the low and ultra low ESR ones, the datasheets didn't have ESR values to compare against. The bad ones are clearly bad. The others all seem to be within spec. I don't have values from a previous point in time, so I can't tell if any others are trending bad. I'm inclined to just replace the four bad ones. Or maybe all the WB ones as that series was indicated as problematic and even Samwha doesn't seem to stock it anymore.

Thanks for the help everyone. I need to re-evaluate my replacement options, too. I had initially picked them based on voltage, capacitance, and ESR, but not max. ripple current. Now that I have most of the Samwha datasheets, that's a lot easier to evaluate.

[wraper]

I ended up getting the DE-5000. I was able to measure most caps in-circuit.

The best way to measure ESR in circuit and ESR for large capacitance in general is setting it into resistance mode at 100kHz frequency.

[nirvdrum]

I'm just finally getting around to ordering these capacitors. The ones I really need to replace are the 10V 3300uF ones. The old WBs had a max. ripple current of 2770mA @ 100kHz. Unfortunately, I can't find an FR that matches that spec. The 10V 3300uF 12.5x25mm FR looks like it'd do it with a 3190mA ripple, but I can't find anyone that stocks it. Arrow, Digikey, and Mouser all only have the 12.5 x 20mm with the 2600mA ripple. I can go with an FM series that has a max. ripple current of 3190mA @ 100kHz, but people seem to really like the FRs over the FMs. The FR looks to be more resilient with a much longer lifetime. If it's got a better construction, is that 160mA difference between the ripple rating on the WB and the FR going to make a real world difference? Or would I just be looking at premature failure that way?

[wraper]

but people seem to really like the FRs over the FMs

There is nothing wrong with FM, they are certainly better than WB even if they were not flawed. Problem with WB is not ripple current rating but that they had an inherent flaw causing their premature failure. And preferences of those people are lame since there is zero research of even anecdotal evidence behind that.