Lcs-8038tx

[zynix]

Hello everyone!

This is my first time to post on Badcaps Forums, so I apologize if I say something ridiculous.

Anyway, as the title says, I have got a Longshine LCS-8038TX ver.M1 LAN card from a friend of mine. The problem is that it isn't identified on my PC as a network device, and the LEDs on it blink hopelessly.

In the picture you will see (hopefully) that capacitor C1 is missing. Could it be the culprit?

TIA,
zynix

[pfrcom]

Re: Lcs-8038tx

Most likely

The picture of a LCS-8038TX in the attached PDF does seem to have a capacitor in that place

Even though yours has a Macronix chipset, and not an Intel like the specification says, the capacitor is probably still necessary

[PCBONEZ]

Re: Lcs-8038tx

Yes you have a missing cap.
The design is to use either radial or SMD in every spot.
The spot you are worried about has the legs from a missing radial still on the board.
.

[zynix]

Re: Lcs-8038tx

Yes you have a missing cap.
The design is to use either radial or SMD in every spot.
The spot you are worried about has the legs from a missing radial still on the board.
.

So, I popping in a 10uF 25V cap (that are the specs of other caps on the board) should solve the problem?

[Uranium-235]

Re: Lcs-8038tx

you can pick up trashed computers in dumpsters with nics in them, I have a few dozen lying around. if your'e really willing to go this far for a crappy nic, then make sure you put it in with the right polarization.

[PCBONEZ]

Re: Lcs-8038tx

So, I popping in a 10uF 25V cap (that are the specs of other caps on the board) should solve the problem?

Can't tell you that for sure. I dunno what was there.
- Often cards like that only have one size cap but that is absolutely not 'always' the case.
.
Chances are that will work but no guarantees..


As Uranium-235 said, replacement NICs are readily available and cheap [or even free].

Fix or replace would depend on what your priorities are.
If repairing this is a learning experience then go for it, if the system is important for whatever reason then replacing it might be better.
.

[Uranium-235]

Re: Lcs-8038tx

when I worked for goodwill CW, I ran by so many tttouusssaaanndds of nics I kept throwing them away in droves. go through any old computers you have lying around, chances you will find one

but yeah if this is for experience reasons, then good luck, smd soldering is hard if you don't have the right equipment and you have a big lack of experience. having ether or is ok, but if you dont' have both, well, good luck

[PCBONEZ]

Re: Lcs-8038tx

They aren't SMD.
Has both SMD and Through Hole Pads. .. 2 mounting options.

[Th3_uN1Qu3]

Re: Lcs-8038tx

That cap is likely on the 12v rail so use a 16v. Try a 100 or 220uf.

[Uranium-235]

Re: Lcs-8038tx

the ones under the smd pads just looks like smaller smd pads, but now a second look, they do look like through holes

[PCBONEZ]

Re: Lcs-8038tx

You can probably figure out what voltage it's on with a DMM and the pin-out.
http://pinouts.ru/Slots/PCI_pinout.shtml
.
A 16v or 25v cap would be safe anyway because the highest voltage is +12v.
.
They probably upped it to 25v for a larger can and a higher ripple rating.
.
Messing with uF on a NIC might have bad results because there are timings and frequency dependent circuits involved.
If you are SURE it is -only- for power to the IC chips then getting the uF exactly right shouldn't matter that much.
.
.

[Th3_uN1Qu3]

Re: Lcs-8038tx

If the capacitor value was critical they wouldn't have used a cheap lytic as they have large tolerances even when they just left the factory door, let alone what happens with aging.

[PCBONEZ]

Re: Lcs-8038tx

Seeing as how the original is missing entirely how did you arrive at a conclusion about what it was?
.

[Th3_uN1Qu3]

Re: Lcs-8038tx

There is room for both thru-hole and SMD, the SMD pads are large, and it is polarized. The only types of capacitor that fit this description are lytic and tantalum. Thru-hole tantalums have larger pitch.

Therefore it must be a lytic.

[PCBONEZ]

Re: Lcs-8038tx

The value........

And the tolerance is +/-20%. That's loose but not THAT loose.

Asker stated the other caps are 10uF.
The missing one was -probably- the same...
100uF and 220uF aren't within 20% of that nor are they within 20% of each other.
.

[Th3_uN1Qu3]

Re: Lcs-8038tx

And the tolerance is +/-20%. That's loose but not THAT loose.

+/-20% in a timing circuit? You're funny today.

I did not read that the other cap was 10uF. That's my bad. But i bet it wouldn't be a problem if it were 100u.

[PCBONEZ]

Re: Lcs-8038tx

+/-20% in a timing circuit? You're funny today.

It's done all the time out in the 'real world'. [Meaning not consumer stuff.]
That's what trim pots are for.
.

[Th3_uN1Qu3]

Re: Lcs-8038tx

Sure but a trimpot is more expensive, not mentioning more failure prone, than a 1% tolerance cap (and there are even tighter tolerances available) so why not do it right in the first place? I don't see a trimpot on that NIC anyway.

[PCBONEZ]

Re: Lcs-8038tx

When you get out of the tunnel you will see more.

[zynix]

Re: Lcs-8038tx

Sorry peeps for not informing you about the...err... progress, but I've had some goddamn school obligations so I wasn't able to respond any sooner. Anyway, I found a shot of my NIC on some Chinese shopping site, and all caps on that picture were having the same specs, so I decided to solder a Licon (yes, I know they suck!) cap that was lying around. And guess what? The card worked just as miserably as it did before I soldered that cap there. Cap isn't dead, and it's soldered properly. OK, I'd say so because there's no shorts and I've taken care for the polarity stuff. Seems like something else died, but not caps, right?