FOAK: Identifying a fried component revisited

So what's the thing in position L1 on the below linked photo then
http://www.homeurl.co.uk/125_2594c.jpg
here's why
http://www.homeurl.co.uk/125_2595c.jpg
Thanks

--
Bob
Currently borrowing a black and red Yamaha XJ750 with fuel injection
Present: Honda XL125RF (FS)
Past: Honda CG125
bob at homeurl tomato dot co dot uk
remove the red fruit if you’d like to email me.

 

Almost certainly a surface mount inductor. e.g.

http://www.easymagnet.com.tw/disclass.cfm?classnumber=39&classname=MULTILAYE
R%20CHIP%20INDUCTOR/CL%20TYPE

Tony

 

I see you have a Realtek 'redefining low end' network card. Possibly
one of the worst network devices manufactured ever.

If you should be looking to replace it, I would really advise a second
hand 3com or an intel 10/100 (think they're called 'etherpro' or
something) card.

If you care, which you may well not

H

 

who cares - NICs are cheap as chips - just throw it away and get
another one.

 

Nowt much wrong with the Realtek devices I've got.

Now they are good, I will agree

--
Catman MIB#14 SKoGA#6 TEAR#4 BOTAFOF#38 Apostle#21 COSOC#3
Tyger, Tyger Burning Bright (Remove rust to reply)
Alfa 116 Giulietta 3.0l (Really) Sprint 1.7
Triumph Speed Triple: Black with extra black bits
www.cuore-sportivo.co.uk

 

OK thanks, probably no chance of finding the value of it though, I'll
chuck it if I can't work it out.

I have several, they are cheap and seem to work well [1].

[1] apart from this one

--
Bob
Currently borrowing a black and red Yamaha XJ750 with fuel injection
Present: Honda XL125RF (FS)
Past: Honda CG125
bob at homeurl tomato dot co dot uk
remove the red fruit if you’d like to email me.

 

Thanks, I'll try and measure it's size and replace it.

--
Bob
Currently borrowing a black and red Yamaha XJ750 with fuel injection
Present: Honda XL125RF (FS)
Past: Honda CG125
bob at homeurl tomato dot co dot uk
remove the red fruit if you’d like to email me.

 

If you have several, stick a ohmmeter across it to check another...

or just chuck it.

 

Really, I have a few and they all seem fine [1], why are they so shit?

I have some of both of these but tend to use them in more important
situations [3].

[1] as long as they're not put in too taxing a situation, I found that
the Realtek 8139Cs and the SIS 900s both caused my smoothwall to crash
when used as the Red interface and my ISP kicked me [2] to give me a new
IP, so I have a 3COM 3c59x as red and that fine.

[2] which it does every 2.5 days

[3] servers and my Smoothwall for instance.

--
Bob
Currently borrowing a black and red Yamaha XJ750 with fuel injection
Present: Honda XL125RF (FS)
Past: Honda CG125
bob at homeurl tomato dot co dot uk
remove the red fruit if you’d like to email me.

 

because I'm a bit of an environmentalist at heart.

--
Bob
Currently borrowing a black and red Yamaha XJ750 with fuel injection
Present: Honda XL125RF (FS)
Past: Honda CG125
bob at homeurl tomato dot co dot uk
remove the red fruit if you’d like to email me.

 

If it's fried, how are you going to measure it?

 

OK, pass it on to an appropriate recycling agency, and get another one.

 

I'd have to de-solder it to get an accurate reading and even then
multimeters are wildly vague, however I may do that [1].

[1] when I fix or replace my multimeter that gave up for no apparent
reason [2]

[2] no it's not the fuse.

--
Bob
Currently borrowing a black and red Yamaha XJ750 with fuel injection
Present: Honda XL125RF (FS)
Past: Honda CG125
bob at homeurl tomato dot co dot uk
remove the red fruit if you’d like to email me.

 

I have more than one card.

--
Bob
Currently borrowing a black and red Yamaha XJ750 with fuel injection
Present: Honda XL125RF (FS)
Past: Honda CG125
bob at homeurl tomato dot co dot uk
remove the red fruit if you’d like to email me.

 

Aha..

 

Maplin are doing BOGOF on domestic test meters @ 4.99
Digital
No idea how accurate they are in absolute terms, but I've had a very
similar one for a while and it does what it says on the tin.
--
Catman MIB#14 SKoGA#6 TEAR#4 BOTAFOF#38 Apostle#21 COSOC#3
Tyger, Tyger Burning Bright (Remove rust to reply)
Alfa 116 Giulietta 3.0l (Really) Sprint 1.7
Triumph Speed Triple: Black with extra black bits
www.cuore-sportivo.co.uk

 

It would be replacing a Maplin analogue one that cost about double that
5 years ago, I kind of prefer the analogue ones as my first multimeter
[1] was an antique AVO one about the size of a car battery and ever
since then I've had a soft spot for lining the reflection of the needle
up with the needle, in a nothing changes they just get smaller way.

[1] it's at my parents house

--
Bob
Currently borrowing a black and red Yamaha XJ750 with fuel injection
Present: Honda XL125RF (FS)
Past: Honda CG125
bob at homeurl tomato dot co dot uk
remove the red fruit if you’d like to email me.

 

Well, the flaws the cards exhibited don't matter as much these days as
they are more 'gross inefficiencies' than pure flaws, but they're
still an inelegant design. ITDealers are doing s/h intel/3com (fxp/dc)
cards for about £2 each, so given that, there's no way I'd deploy a RL
card.

Here's the relevant comments from the guy who wrote the realtek
driver, taken directly from the source code.

<quote>

Written by Bill Paul <email@address>
Electrical Engineering Department
Columbia University, New York City

The RealTek 8139 PCI NIC redefines the meaning of 'low end.' This is
probably the worst PCI ethernet controller ever made, with the
possible
exception of the FEAST chip made by SMC. The 8139 supports bus-master
DMA, but it has a terrible interface that nullifies any performance
gains that bus-master DMA usually offers.

For transmission, the chip offers a series of four TX descriptor
registers. Each transmit frame must be in a contiguous buffer, aligned
on a longword (32-bit) boundary. This means we almost always have to
do mbuf copies in order to transmit a frame, except in the unlikely
case where a) the packet fits into a single mbuf, and b) the packet
is 32-bit aligned within the mbuf's data area. The presence of only
four descriptor registers means that we can never have more than four
packets queued for transmission at any one time.

Reception is not much better. The driver has to allocate a single
large
buffer area (up to 64K in size) into which the chip will DMA received
frames. Because we don't know where within this region received
packets
will begin or end, we have no choice but to copy data from the buffer
area into mbufs in order to pass the packets up to the higher protocol
levels.

It's impossible given this rotten design to really achieve decent
performance at 100Mbps, unless you happen to have a 400Mhz PII or
some equally overmuscled CPU to drive it.

....

Here's a totally undocumented fact for you. When the
RealTek chip is in the process of copying a packet into
RAM for you, the length will be 0xfff0. If you spot a
packet header with this value, you need to stop. The
datasheet makes absolutely no mention of this and
RealTek should be shot for this.

</quote>

The cards themselves tend to use cheaper components and aren't as well
insulated from the line as other cards - you _might_ notice the lack
of a small black rectangular component on the board, generally
manufactured by CP Clare - that being an optoisolator which
electrically isolates the computer-side of the card card from the
network-side of the card, which you'll find on better cards but is
noticeable by it's absence on cheaper cards. That's not RL's fault,
but the fault of the card manufacturer, but it's still indicative of
shoddy corner-cutting design.

Anyway, there ends the lecture

H

 

Harvey wrote:
<snip RTL8139 is puke>

Furry muff, I'll take your word for it and not buy any more, [1] has the
chap got anything to say about SIS 900s as they are a similar price?

[1] I'll try to give the ones I have got away

--
Bob
Currently borrowing a black and red Yamaha XJ750 with fuel injection
Present: Honda XL125RF (FS)
Past: Honda CG125
bob at homeurl tomato dot co dot uk
remove the red fruit if you’d like to email me.

 

I had a look for you and I couldn't find anywhere near as much
criticism of the SIS cards. The same guy did write the driver for it,
and instead of there being 'this following code is to allow for [this
shit undocumented behaviour of the chip] every 5 lines, we just had...

<quote>

Written by Bill Paul <email@address>
Electrical Engineering Department
Columbia University, New York City

The SiS 900 is a fairly simple chip. It uses bus master DMA with
simple TX and RX descriptors of 3 longwords in size. The receiver
has a single perfect filter entry for the station address and a
128-bit multicast hash table. The SiS 900 has a built-in MII-based
transceiver while the 7016 requires an external transceiver chip.

Both chips offer the standard bit-bang MII interface as well as
an enchanced PHY interface which simplifies accessing MII registers.
The only downside to this chipset is that RX descriptors must be
longword aligned.

</quote>

So I'd say they're safe to use!

H