Sceptre x22wg-Gamer 22" LCD

[notajoo]

Re: Sceptre x22wg-Gamer 22" LCD

Yeah, I can't actually find the exact cap for capxon that I'm replacing. The one I'm looking at is 10mm wide rather than the 8mm mine is, but everything else seems the same so I went with that.

Also, what I was referring to about there being separate columns is when you actually use the search function on digi-key. Most of the ESR ratings are blank though in the listings as are many of the impedances. The ones that do show both ESR and impedance have different values in each column, so they aren't the same thing it seems.

I'm having no luck at all when trying to find an acceptable difference in impedances between caps so I'm thinking I may just have to order these ones since they are the only ones with specs that seem close at all and just hope that it works.

[retiredcaps]

Re: Sceptre x22wg-Gamer 22" LCD

Ok, so ESR and Impedance is the same thing then? When looking on digi-key and mouser it lists the ESR and Impedance in separate columns so I just assumed it wasn't the same thing.

I'm looking at digikey's Panasonic FM datasheet at



I only see impedance and no separate column for ESR.

That post says only around 30% lower is normally acceptable and the change between the two I'm looking at is about 46%. Will I be taking a significant risk by using the new caps because of that?

PCBONEZ is the expert, but some other members here are less exacting about choosing replacements when it comes to ripple and ESR including myself. Sometimes you cannot find datasheets for the "old series" or the right sized cap, so you approximate.

[notajoo]

Re: Sceptre x22wg-Gamer 22" LCD

Ok, so ESR and Impedance is the same thing then? When looking on digi-key and mouser it lists the ESR and Impedance in separate columns so I just assumed it wasn't the same thing. I did see the term used interchangeably on a few posts here on the forums, but when I googled it I couldn't find any information regarding what the difference was between the two terms, if any.

So now that raises another question (of course ). That post says only around 30% lower is normally acceptable and the change between the two I'm looking at is about 46%. Will I be taking a significant risk by using the new caps because of that? It's the only available cap I can seem to find that will match the uf and voltage with dimensions that will fit on my board, so I'm really hoping it will be acceptable to use.

[retiredcaps]

Re: Sceptre x22wg-Gamer 22" LCD

The dimensions and other specs match near perfectly, and the faqs on the forum here say it's okay for ripple to be higher, but I can't find anything about acceptable impedance differences.

Lower ESR is better. See PCBONEZ talk about it here

https://www.badcaps.net/forum/showpo...30&postcount=7

[notajoo]

Re: Sceptre x22wg-Gamer 22" LCD

Ok, I was out of town for a week or so for the holidays. I'm back now and about to try to order the new caps I need. I found a near perfect match for the medium caps I listed earlier on the thread, but it has a lower impedance by quite a bit so I wanted to check first and make sure it would be okay to use. I browsed the threads that retiredcaps posted earlier but couldn't find anything about what acceptable amounts were for impedance differences between original and replacement caps.

My original cap is 1200 ripple and .076 impedance according to the manufacturer documents I found. The replacement is 1240 ripple and .041 impedance. The dimensions and other specs match near perfectly, and the faqs on the forum here say it's okay for ripple to be higher, but I can't find anything about acceptable impedance differences. Thanks in advance for any help provided.

[mockingbird]

Re: Sceptre x22wg-Gamer 22" LCD

No, I have a feeling that Bill was correct when he said:

1. Either deliberately or in error the supply voltage to the Pericom IC was connected to the 5V rail. As a matter of faith I believe a designer will NEVER intentionally release a design which will kill an IC. However, mistakes do happen. Also, it is possible that Pericom has upgraded their design and the IC can now operate from 5 Volts. Neither of these are likely, hooking an IC designed for 3.3 volts to a 5 volt supply will result in an early (spectacular) failure; there is no reason to allow operation from 5 VDC.

Considering Sceptre has a near 100% failure rate on the DVI ports of this series, it seems to me they lazily designed it defectively.

[nathias]

Re: Sceptre x22wg-Gamer 22" LCD

Any luck getting the dead DVI port working again?

[mockingbird]

Re: Sceptre x22wg-Gamer 22" LCD

I'm finding it very difficult to take resistance readings from the IC to the regulator, because it keeps fluxtuating wildly on my DMM, an at any setting or polarity, my DMM shows a "-" before the number.

But here are the results for ground to 48 and 1, black on ground and red to the IC:

Pin 1: 43
Pin 48 : Nothing

[PlainBill]

Re: Sceptre x22wg-Gamer 22" LCD

Thanks. I appreciate your patience. What about polarity, does it matter which probe goes where? Because I am getting different readings in reverse.

That is significant. Let me give a little background here, and explain my thought processes.

The datasheet for the Pericom IC indicates the maximum supply voltage is 3.3V. The voltage you are measuring is essentially the same as the input voltage to the logic card, 4.97 VDC. There are two possible reasons for that:

1. Either deliberately or in error the supply voltage to the Pericom IC was connected to the 5V rail. As a matter of faith I believe a designer will NEVER intentionally release a design which will kill an IC. However, mistakes do happen. Also, it is possible that Pericom has upgraded their design and the IC can now operate from 5 Volts. Neither of these are likely, hooking an IC designed for 3.3 volts to a 5 volt supply will result in an early (spectacular) failure; there is no reason to allow operation from 5 VDC.

2. The regulator supplying the 3.3 VDC to the Pericom IC has failed, and is supplying 4.97 VDC instead. Note that the output of LDO (low drop out) regulators will typically be at least 1 Volt below the input voltage. This implies that the regulator is shorted. But I believe I have identified all regulators, none are shorted.

So to eliminate possibility 1, I had you check the resistance from the 5V supply to the supply input of the Pericom IC. And you seem to be saying there is no short. So once again I am wondering WTH is going on?

Just to preserve my sanity, please check the resistance from ground to pin 1 and to pin 48 of the Pericom IC. Also check the resistance from 5V to pin 1 and pin 48. If reversing the probes gives different readings, report both readings.

PlainBill

[mockingbird]

Re: Sceptre x22wg-Gamer 22" LCD

Thanks. I appreciate your patience. What about polarity, does it matter which probe goes where? Because I am getting different readings in reverse.

[PlainBill]

Re: Sceptre x22wg-Gamer 22" LCD

I made a mistake before and I measured Pin 25 (VD0) and you wanted 48 - VDD. But now I looked at the datasheet and I can tell which it is. No worries though, because the measurement is exactly the same.

Regarding the resistance check... Which Ohm setting should I have the meter at? Also am I correct in assuming that common probe will go on the regulator and red probe on pin 48?

Use the lowest ohms setting. As a general rule, always use the lowest range which will give a meaningful reading. In other words, if you are measuring and unknown resistance you MIGHT start at the 20 Megohm range. If you get a reading of 0001 you should reduce the range to the 2 Megohm, 200 Kohm, etc until you get a reading like 000.3.

PlainBill

[mockingbird]

Re: Sceptre x22wg-Gamer 22" LCD

Good work, but Darn!!! I would have expected one of those voltages would be incorrect, they are all reasonable. I was hoping for a shorted regulator.
Check the resistance between pin 48 of the Pericom IC and the right hand pin of U7 (the one that is at 4.97 volts).

I made a mistake before and I measured Pin 25 (VD0) and you wanted 48 - VDD. But now I looked at the datasheet and I can tell which it is. No worries though, because the measurement is exactly the same.

Regarding the resistance check... Which Ohm setting should I have the meter at? Also am I correct in assuming that common probe will go on the regulator and red probe on pin 48?

[retiredcaps]

Re: Sceptre x22wg-Gamer 22" LCD

So since the smaller one has plenty of height to play with, a 2.5 or 3.5 LS would be okay to use as long as the uf and v and the other dimensions match?

Yes. I have seen small caps not sit flush to the board. As an example, here is one board I have.

https://www.badcaps.net/forum/attach...1&d=1275510343

See how c102, c807, and c114 all sit off board? And this is from the factory.

Note c814 and c831 sit flush (again from the factory).

You will see this on other boards as well.

edit: more examples (see how small cap sits off the board - not flush - all photos from De3rcr - excellent clear focused pics)

https://www.badcaps.net/forum/attach...3&d=1292186500

https://www.badcaps.net/forum/attach...0&d=1290283049

https://www.badcaps.net/forum/attach...0&d=1289502289

[notajoo]

Re: Sceptre x22wg-Gamer 22" LCD

Lead spacing does not have to be exact. Caps don't have to fit flush against the pcb unless height is a problem.

So since the smaller one has plenty of height to play with, a 2.5 or 3.5 LS would be okay to use as long as the uf and v and the other dimensions match?

I did assume that the Ebay sellers did that, but since I can't seem to find anything compatible in stock, if they have it ready to ship I would rather spend a few dollars more and go ahead and get it than to wait a month or more. I will definitely get detailed specs though before I go that route since they don't have it listed on the auction page. It just says it's a full capacitor replacement for the same board and lists the uf and temps. As long as I can be assured that the caps are from a reputable brand and matching specs then I think that's the route I'm going to have to go.

[retiredcaps]

Re: Sceptre x22wg-Gamer 22" LCD

I did find on Mouser one that's almost exact in the panasonic FR series, but 15mm height instead of 16mm.

I'm guessing the lead spacing has to be exact so that's a no-go on the smaller one.

I'm starting to think I should just contact the person selling the ebay kit and make sure they have exactly what I need in a good brand and if so, order from them instead.

The Panasonic FR would match ideally with the 470uF 25V 8.00mmx16.00mm cap, but as you found out it is on backorder.

Lead spacing does not have to be exact. Caps don't have to fit flush against the pcb unless height is a problem.

If you go the ebay route, make sure to ask for the dimensions of the caps. Most ebay sellers buy their caps from the same place (digikey, mouser), but they buy in larger quantities to get the price discount.

[notajoo]

Re: Sceptre x22wg-Gamer 22" LCD

The 8 medium sized caps are 8mm wide, 16mm tall, 470uf, 25v, 3.5mm lead space, 105c temp.

The 1 small cap is 5mm wide, 11mm tall, 33uf, 35v, 3mm lead, 105c temp.

I've looked on both sites you listed and can't seem to find either one that has exact matches for them. Digi key's closest height is 20mm on the medium sized equivalent and that will be cutting it way too close for my taste. They would practically be touching the case. I did find on Mouser one that's almost exact in the panasonic FR series, but 15mm height instead of 16mm. Even if I could go smaller than the original though which I'm not sure of, they are on backorder and I wouldn't get them for about a month. Not to mention Mouser's shipping rates are pretty ridiculous.

As for the smaller cap, digi key doesn't even have a 3mm lead spacing option to choose and even if I don't put that in, there isn't one that comes up. I'm guessing the lead spacing has to be exact so that's a no-go on the smaller one. On mouser you can't even search for LS, but when I put in the other specs every one that shows LS in the description is 2, 2.5, or 3.5 mm or higher, so a no-go there as well...

All in all it's not looking very optimistic. I'm starting to think I should just contact the person selling the ebay kit and make sure they have exactly what I need in a good brand and if so, order from them instead. Anywhere else I might look or am I just doing something horribly wrong in my searching somewhere?

[retiredcaps]

Re: Sceptre x22wg-Gamer 22" LCD

Does the height include the height of the leads that go through the board also or is it just the height of the actual capacitor itself?

The latter.

The one I was looking at earlier is 4mm bigger in height than my capacitor measures but matches in every other way, so that's why I was wondering.

Please list your original caps.

edit: Note caps can be wider and taller than the original as long as it fits.

[PlainBill]

Re: Sceptre x22wg-Gamer 22" LCD

Ok, I measured the voltages. Here are the results:

Good work, but Darn!!! I would have expected one of those voltages would be incorrect, they are all reasonable. I was hoping for a shorted regulator.

Check the resistance between pin 48 of the Pericom IC and the right hand pin of U7 (the one that is at 4.97 volts).

PlainBill

[notajoo]

Re: Sceptre x22wg-Gamer 22" LCD

Does the height include the height of the leads that go through the board also or is it just the height of the actual capacitor itself? On digi-key there are none that match the dimensions and specs of my capacitors. The one I was looking at earlier is 4mm bigger in height than my capacitor measures but matches in every other way, so that's why I was wondering.

[mockingbird]

Re: Sceptre x22wg-Gamer 22" LCD

U6 is probably an adjustable regulator. Do as jetadm123 suggested, but measure the voltage on all three pins of each regulator. The tab on each regulator is electrically connected to the center pin.

Ok, I measured the voltages. Here are the results: