Dan's Data letters #24
Publication date: 27-Jan-2003.Last modified 03-Dec-2011.
Slightly too high?
I had a friend buy me a portable MP3 CD player in Hong Kong over Christmas. In Hong Kong, the national voltage is 220 volts, but here in New Zealand it's 240 (approx 238). The CD player comes with an AC adapter, which supposedly converts 220 volts AC to 4.5 volts DC.
My question is, would it hurt the CD player if I used an adapter to just convert the Hong Kong plug to NZ, and plugged it into 240 volts instead of 220?
Etienne
Answer:
No, it won't - or at least shouldn't - hurt anything. Different countries
have different nominal mains voltages, but except for some very peculiar
backwaters, 110 to 120 volt countries are all the same, as are 220 to 240
volt countries. Different people can describe their country's nominal voltage
differently, depending on where and how they're measuring it. Generally
speaking, though, appliances of all sorts should be fine running from anything
in their own nominal range, whether that's one-hundred-and-something or
two-hundred-and-something. They might care about the frequency of the alternating
current; non-quartz electric clocks, for instance, will run slow if they
come from a 60Hz country and you plug them into 50Hz power. Most gadgets
don't care about that, though.
Nowadays, there are also quite a lot of devices with manually switchable, or auto-adapting, power supplies that can run from either voltage range.
There's some more info on this issue here.
Cables and plugs
Two quick questions.
1. What is the maximum length a standard blue CAT5 network cable can be?
2. I was in the USA for Christmas and was given a Logitech MX-700 mouse. Unfortunately it has an American power plug on it. The input range is 100-127V~0.3A 50-60Hz.
Could you give me any advice on how to run this mouse here in Australia?
Ben
Answer:
As I mention in my old piece
here, the length limit
for 10/100BaseT cables is 100 to 150 metres, but it depends on the cable
quality.
To run your mouse's receiver/charger plugpack in Australia, you'll need a step-down transformer. Jaycar's $AU49.95 MF1091 transformer should do.
Net sharing
I've got 3 PCs on a network at the moment. One is connected to the cable modem and the other 2 PCs connect to the PC connected to the cable modem and I have Internet sharing that way. Someone told me I could get a Router and then plug the cable modem directly into that. And then all I have to do is plug each PC into the router and I'll have Internet access on all PCs.
Is this correct? Are there any limitations? Does it work with Optus cable?
Russell
Answer:
Yes, you can use a dedicated sharer box with Optus cable. You may find my
old-ish piece here informative.
Troubleshooting, but troublemissing
I came across your site while trying to solve a problem I had created.
Plan: Buy 2 new motherboard and processor combos, 2 new cases, and slap some old hard drives and memory in.
MSI 6389 motherboard and Duron 900 arrived with el cheapo 300w case.
I promptly installed the gear in the case. I hit the power button and the fans spun up - wonderful. Unfortunately nothing further occurred. No POST, no video, etc. I switched to a non-onboard AGP video card and received the same result. I unplugged all peripherals except monitor, unplugged NIC, keyboard, mouse, and IDE/floppy cables from the board. Same result. So now I'm thinking "OK, memory, CPU or board". I switch out memory first, and same result. I have a Gigabyte 7ZX-H motherboard that is in my working system with a 1.4GHz Athlon running fine. I think, well, the 900 should work on that. I turn down the FSB and put the 900 in that machine. Same result. So now I figure that we have a bad CPU. I sneakily realize that the 1.4 will work in the MSI board. I turn up the FSB on that board and place the 1.4 in that machine - you guessed it - same result.
So now I've concluded 1. I have a bad board and bad 900 processor. 2. I had a bad board or processor and one of them infected the other 3. I have some bad voodoo working against me and I should just quit building computers for awhile.
Well it turns out I should have stuck with the third idea because things only went downhill. I decided on RMAing the board and cutting my losses with the processor (morally I cannot RMA the 900, because I really think the board is the culprit). I then go to put the 1.4 back in the Gigabyte board and am terribly unhappy to find that the silicon jihad that has been leveled against me has somehow breached the 8 foot distance between the two systems, and now I have no POST on the gigabyte board and Athlon chip - which were working just minutes ago.
This occurred 2 days before I had 16 people coming over to my home for a LAN party, and suddenly I find myself sans PC.
I figure a new XP 1700+ will work in the gigabyte board nicely, and they've come down in price recently. I pay nearly $30 to have it overnighted, and put it on my Gigabyte board, only to find out that this too has succumbed to the "sickness" my other hardware had recently presented with.
I buy a new cheap ECS motherboard from a local retailer at a horribly gouging price, but hey I have to have a machine, with a LAN party in my basement the next day. I put the XP 1700+ in the new board and, mercifully, POST to a BIOS. It looks like my hardware layer is different, even though they are the same chipset, and I'll have to overlay or reinstall - not a problem. Hardly an obstacle after the last couple of days.
I somehow am dragged into the quagmire again, however, by a "friend" who cannot believe that the Gigabyte board doesn't work ( to his credit I agree it is unusual to even comprehend that a bad board could destroy a processor in such a way that the processor could destroy a motherboard which could then turn around and destroy another processor - well at the time it was a compelling argument and he and I had a desire to know what had occurred.)
I decide to follow the deceiver, and we try the 1700 in the Gigabyte board again - with the same results. Well now that luck has been tempted twice he decided to let me have it. Yep, the 1700 was now "not working" when we placed it back into the ECS board. At that point I closed the door to that room, lit some candles and said some prayers.
I also thought at one point that the PSU was suspect; I downloaded the ATX 2.0 spec and plugged some hard drives/CD-ROMs into the PSU and hit the pins with a multimeter - everything was in spec.
So now, hoping against hope that you are still reading this, I was curious if you had any suggestions on my problem solving methodology. I learned some things about what not to do - e.g. do not mess with a computer that you absolutely need the next day - but I still don't know what the root of the problem was, and quite frankly it is eating at me.
Jeff
Answer:
You didn't do anything very wrong, procedurally, but things may nonetheless
not be as they seem.
The human brain is a pattern-finding device; humans love to jump to conclusions that seem to match a pattern, even if that pattern involves ghosts or curses or mysterious "hardware viruses". There are, of course, lots of real patterns in the world, but there are also lots of coincidental events that just seem to have some sort of plan behind them. Seeing patterns where none exist can, in extreme cases, become pathological.
You could have a "hardware virus" sort of issue - they do exist. But you could, instead, have a combination of an unremarkably defective motherboard, and static damage from less-than-perfect antistatic precautions on your part. Which is not an insult; I regularly work on PCs using nothing but the touch-the-chassis-when-you-remember-to level of static control. But a computer that's been worked on that way for some time may well be teetering on the brink of failure; static damage is commonly progressive, pushing components further and further out of spec until they no longer work. Something in PC B goes out of spec as you move a component into it from PC A; it thus looks as if the PC A component killed it, when it actually didn't.
There could, however, very well be a real transmissible problem. Sometimes one device really does do something to another device that turns that other device into a murderer of everything you subsequently plug it into.
My favourite, quite simple, example of such a "hardware virus" is the simple case of a plug - usually a HD15 monitor plug, or some similar fiddly D-connector - with a loose pin. The pin doesn't make contact, the connection doesn't work right, and the monitor appears defective, although actually it's just got a dud plug. When you unplug that monitor, though, the loose pin comes off, and stays stuck in the socket. Now, if you plug another monitor in with sufficient gusto, you'll squish a pin in its plug - and if you do it just right, you'll make that pin loose. Lather, rinse, repeat; each newly made bad plug can create another bad socket.
Analogous things can happen with solid state devices. A defect on a motherboard that fries a CPU such that it now has a short between a power input and ground, for instance, will mean that that CPU will barbecue any motherboard you plug it into in the future.
There's not much of a moral to this story, other than that it pays to write down what happens and be Sherlockian about it. Don't assume a connection when one is not logically necessary.
Fun with Macrovision
I have a Radeon 64MB DDR VIVO card (before they started the fancy numbers) that I've been using as a video feed for some time. I hook up a VCR to the line-in and watch TV, which saves me hauling around an extra 30 lbs of CRT for a proper television. I never had any real problems with it until a few months ago, when I mysteriously started seeing my picture go light-dark-light-dark when watching VHS tapes. I talked to the guys at the store where I got the tapes, and they said Macrovision was the problem. I assured them that I was not trying to dupe the tape, but they said MV was definitely the cause. So, I poked around a bit and found that simply running a Macrovisioned signal through a VCR (e.g. connecting a DVD player to it) can trip the protection and ruin your picture.
Apparently, my video card was doing the same thing (acting as a second VCR). I have the same problems trying to watch DVDs from my PS2 on the computer. When I originally got the card, the manual said that the "record" button on the video-viewing software (ATI's Media Center) would be disabled if a Macrovision signal was detected. I don't remember that happening, but it definitely didn't say there'd be picture distortion.
I wrote to ATI, and as you might imagine they were less than helpful. They basically told me that it was a measure to keep people from copying protected media. I told them that I didn't want to copy anything, I just wanted the card to behave as advertised. I pointed out the aforementioned note in the manual. This was pretty much ignored, and I was told that no fix was planned.
So, after much rambling, I get to the question: do you know of any way that I can watch my VHS or DVD movies through my video card without annoying distortion? I say again that I have no desire to record them, just watch them peacefully. Any help?
James
Answer:
Yes, passing a
Macrovisioned
signal through a VCR is a bad idea, and some other consumer video gadgets
don't like it either. The solution is to use a Macrovision blocker (or "buster"
, or "scrubber") between the video source and your computer.
Macrovision eliminators are easy to build (reference), but if you're not quite up to that, they're also quite easy to buy. Reputable electronics stores don't put them on the shelf with a sign that says "Hey! Video pirates! Check this out!", but if you look for a video "enhancer" and/or "stabiliser", you're likely to find that by an extraordinary coincidence, that device blocks Macrovision as well.
The enhancer/stabiliser nomenclature isn't a complete euphemism; good versions of these things also have a high frequency boost function to sharpen up tape transfers, and can have other features like Teletext blocking, to get rid of further extraneous stuff that you don't need on tape.
Upgrade quandary
I spent a few hours trawling through AMD's sites and found that Athlons faster than 700MHz have a problem with the KX133 chipset used in my AOpen AK72 motherboard. I then spent just 5 mins reading your old review of the 700MHz Thunderbird to get the same and better info!
I was hoping you had tried upgrading the CPU but sticking with the same motherboard (Slot-A). I was hoping to buy an Athlon XP 2100+ but don't think it's worth the effort now, as I would need some type of Slot-A to Socket A adaptor.
What do you recommend I upgrade to CPU-wise, but keeping the AK72 motherboard?
Paul
Answer:
There's no such thing as a "slotket" adapter for Athlon systems; one or
two of them were rumoured products, but they never got off the ground. This
leaves you with no good upgrade options at all. Faster Athlons than the
one you've got may or may not work (an 800MHz CPU has a good chance of working,
but who cares, since it'd only give you a 14% speed gain...), and the fastest
Slot A Athlons ever made aren't that much faster than what you've
got already. Stick with what you've got until you're ready for a motherboard
change.
