Could you post a better picture of the area with the SMD inductors on the T-con?
I see about 8 ceramic caps connected to the input 12V rail after the fuse.
It could be that those are bad or it could be a shorted MOSFET (or T-con inverter IC has built-in MOSFET?) on the AVDD rail... or shorted ceramic cap + rectifier diode on the AVDD rail.
Voltage injection might or might not work too well. Ceramic caps often do a "hard" short-circuit, acting like a piece of wire. So finding the bad one with voltage injection may get tricky. Of course, if you're experienced with...
momaka
master hoarder
Last Activity: Yesterday, 07:22 AM
Joined: 05-04-2008
Location: VA (NoVA)
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Doesn't matter. I have a few red (or was it green[?], I forget now) LEDs like that, where the big "cathode" side seen inside through the LED lens is actually the Anode. I just flip those around and they work fine.
Or are you dealing with 3-terminal LED's here??Leave a comment:
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Good save!
I don't think you can get a decent 5V 3 Amp power adapter like that for $1 new from the store.
The one shown above is built very well - it has an input choke, proper fuse and thermistor, an and proper X2 and Y2 caps.
All the cheapo adapters I can get new here (for more than $1, mind you) are gutless wonders with 1kV ceramic caps between primary and secondary, and a bunch of other cost-cutting measures.
For someone as far behind as I am on the hardware curve, I'd say a GTX 560 (be it SE or not) is still a very decent video card.
What's...Leave a comment:
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If you live in a country with 230V or 240V AC, you can do that by either removing the APFC MOSFETs or just by disabling their Gate drive circuit.
However, some APFC controllers may not be happy just with this. For these, you might also have to "trick them" by changing a few resistor on their voltage feedback pin so that the APFC IC "thinks" the rectified 230/240V (~340V DC) is actually the proper level the APFC is trying to boost to.
As for weather the PSU can be loaded up to 80%... or even that much.. that will depend on the PSU itself.
I tried it...Leave a comment:
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Some POST cards are indeed flaky... well, more like, it depends on which PCI slot they are inserted. The one I have is like this - on some motherboards, I don't always get POST codes, depending on which PCI slot I used. Also, it doesn't appear to use gold contacts but rather tin contacts on its edge connector, so sometimes it takes a bit of "wiggling around" in the PCI slot for it to read codes.
I think it's OK.
You could ask the mods to move it to the Motherboard repair section if you like.
Generally, a short between Gate and Source (or...Last edited by momaka; Yesterday, 05:45 AM.Leave a comment:
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That sounds like a clever and a silly circuit at the same time.
In any case, I would suggest OP to use an X2 -rated cap for that position, given that the capacitance is rather small. While X2-class caps won't necessarily always go open-circuit in the case of a surge / over-voltage, they are usually a little more tolerant of abuse / line voltage spikes. So using one as a capacitative dropper might yield better reliability.Leave a comment:
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Hmmm, that's an interesting fault.
The only difference (to the PSU) when the system is in soft-off (turned Off) state and sleep (standby) is perhaps current draw on the 5VSB should be higher.
Try this test:
Put a load on the PSU (like an HDD or two, or possibly more stuff, like a few 12V auto bulbs on the 12V rail) and try powering it on by grounding PS_ON signal. Does the PSU turn On normally? Can you do this a few times in a row both quickly after each other and spaced apart in time?
Now repeat the above test, but this time, after you power on the PSU, put a load...Leave a comment:
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The pictures are too small for me to be able to trace out anything on the board... but going by your description ("The diode goes between the center lead and the + of the high voltage caps") and from what I can see from the general layout of the PSU, this sounds like the rectifier diode for the APFC boost circuit. In any case, since it's on the primary side, don't go with anything less than 600V for the rating. Being that it's a 12V 12 Amp PSU (~144 Watts), probably best to go with a current rating of at least 2 Amps.
Since this diode blew, it might be worthwhile checking...Leave a comment:
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With that MOSFET is burned the way it is, check T-con board for short-circuit on the 12V rail that goes to the T-con board (the board attached to the TFT screen with film cables, usually) and all of the secondary voltage rails on the T-con. Chances are that MOSFET blew up because something on the T-con shorted. Pictures of the T-con would help further throubleshooting. Generally, the secondary voltage rails on the Tcon are AVDD, VHG, VGL, VCOM... and a few more. They are labeled with round test points usually. IME, any of these rails shorting has been due to a shorted ceramic cap somewhere. If...Leave a comment:
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Well, since you want to have a red LED in place of a blue LED, the answer is simple: you don't need to remove the blue LED at all. Just install the red (or green) LED in parallel to the blue LED. Since red and green LEDs have a lower voltage drop, they will begin to conduct way before the blue LED does. Thus, the blue LED should not light up at all (or it might just barely, but I doubt it would be too visible.)
In fact, I just helped a family friend's kid with an issue like this last week. He was doing a project for an intro Engineering class and couldn't understand why from the two LEDs...Leave a comment:
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I agree with stj.
360-380V DC should be about the acceptable range, at least for PSUs that use 2x 200V caps in series (most non-APFC PSUs.)
For PC PSUs with APFC ("full range" 100-240V AC input, no voltage selector switch), you could go even higher (up to 400V DC) if the primary cap is specced higher, like 420V or 450V. For 450V caps, I suspect up to 420V would be OK. Definitely wouldn't push it further, though, just so that there is some headroom for noise and voltage spikes on the input. And you might have to remove the MOV's, as sjt suggested. Otherwise
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Last edited by momaka; 04-23-2024, 09:42 AM.Leave a comment:
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Either you have more bad capacitors or something else went wrong from last time when the TV "screen begin to dark and It finally did not display at all for hours.."
Do you see an orange glow from the TV's neck close to the neck PCB on the back? You should after a 10-20 seconds of the TV being turned On. Missing heater voltage would be one reason you are not getting an image. Lack of output to the HOT (Horizontal Output Transistor) or the HOT being bad could also be the reason.
So you need to do more parts checking. The small caps on the neck board could also...Leave a comment:
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I highly doubt the issue is with the caps here. All of the electrolytic and polymer caps are good brands, so they are extremely unlikely to fail... and your ESR readings confirm this. So personally I wouldn't waste any time with a recap here.
FWIW, I have audio gear with 30-40 year old Japanese electrolytic caps, most of which still measuring in spec after all this time.
Electrolytic caps don't (easily) go bad sitting on the shelf. It takes many (10+) years of no use and a very sensitive circuit for any issues to arise... at least for the good Japanese brands.
How was...Last edited by momaka; 04-23-2024, 06:02 AM.Leave a comment:
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FWIW, I've never been able (or bothered) to remember which variation of Ching/Chang/Chong/Cheng +/-X (sorry, that probably sounds racist now that I think about saying it like that, though that wasn't the point here
) is the "genuine" one. So I [I]genuinely[/I] threat them all as likely junk. Granted I've seen TLC/Roku TV sets use these (the "Chang" variant) in their PSUs... and in the one I found, the LED backlights blew before the caps did... so I suppose they aren't all *that* bad if they outlasted the LED backlights. And a few years ago, I found a pair of free Logitech...
Last edited by momaka; 04-23-2024, 05:42 AM.Leave a comment:
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If I remember correctly, SamYoung SMS series are general purpose capacitors... as are Rubycon YK series. So in cases like that, I rarely bother to look into the datasheet. If there is any difference in RC, it's going to be too small to matter - just IME.Leave a comment:
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Yes, low impedance / ESR caps are usually specified at 100 KHz... which simply means they will do OK with both high frequency (100 KHz or more) circuits as well as low frequency circuits (120 Hz.)
Yes, will be fine.
Most SMPSes are better off with low impedance caps anyways....Leave a comment:
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Nice work! That is one helluva custom unit!!
The white silicone on the new parts (caps) looks as if this was completely done at the factory... and why those shots in post #9 above also fooled me to think your unit wasn't a Seasonic S12II build, just like dmill89 thought too.
Leave a comment:
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I think it's more of a "negligence" problem - i.e. no one thinks or cares to "care for" stuff that is not theirs, so stuff gets left turned On all the time. This then makes everyone used to the fact that everything is always On and working without thinking about it. And when it's not working, they forget to check the simple stuff - i.e. is it plugged in, turned On, and etc. Most people also hold onto the idea that they should only do what they are paid to do at work and nothing more. So if something is not working and it's not their responsibility, they don't go out of their...Leave a comment:
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Most MCZ (and MFZ) I found on eBay were genuine, but rather old stock.
The 6.3V ones may indeed be a bit "unstable", especially used ones pulled from old boards, and also if they have sat unused for very long... at least that's my personal experience.
MBZ, on the other hand, seem to hold up OK. Haven't had issues with any yet.
That said, Panasonic FR, FM, and FS along with UCC KZH and KZM and Nichicon NV/HW can often be "good enough" for most motherboard use cases.Leave a comment:
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Yes, it will be fine. Most CRT TVs use general purpose 85C caps, so any 85C or 105C general purpose caps or any low-ESR caps will be fine. Samxon GF is entry-level low ESR, so it will work... though I can't really highly recommend Samxon GF, since it is known to be a problematic series. But chances are, it should still give you more than a few years of useful life on that TV, so go for it.
BTW, it might also be a good idea to double-check the old caps with the ESR meter once you remove them from the PCB, just in case, as sometimes in-circuit measurements can be inaccurate.
I...Last edited by momaka; 04-17-2024, 07:40 AM.Leave a comment:
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