A computer components & hardware forum. HardwareBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » HardwareBanter forum » General Hardware & Peripherals » General
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

AM radio noise



 
 
Thread Tools Display Modes
  #1  
Old July 23rd 03, 10:11 AM
Randy
external usenet poster
 
Posts: n/a
Default AM radio noise

I've had this problem awhile but it seemed to be getting worse. My
computer pretty much wipes out my AM radio (FM unaffected). All the
wall sockets in my room are on the same circuit so I'm out of luck
moving the radio. Now... I expect the AM radio to go bonkers if the
system is on but this happens when the computer is off too. If I
switch the power supply to off in the back of the case all is well. Is
this normal?

The graphics board always has a light on (Radian 9600 pro) for the 8x
agp but I wouldn't think this would have that kind of affect. I hooked
the computer up to a belkin surgemaster with a high frequency
capacitor to no avail. I hooked my AM radio to the same surge
protector and again zippo.

Could the power supply be the culprit? If so are there ones on the
market anyone could recommend that wouldn't contaminate the AC line of
the house?

Thanks

Randy
  #3  
Old July 23rd 03, 03:36 PM
w_tom
external usenet poster
 
Posts: n/a
Default

Common problem when that computer expert selected a power
supply based upon price rather than on technical specs. Power
supplies must have an in-line filter. But many important
functions are forgotten to sell power supplies at less than
$80. Missing functions when a power supply is not provided
with a long list of specifications including:
PFC harmonics compliance: EN61000-3-2 + A1 + A2
EMI/RFI compliance: CE, CISPR22 & FCC part 15 class B

Where does that surge protector even cite numbers for noise
reduction? It remains inert - does nothing - until voltages
above 300 volts are observed. But then even that number is
often in small print. Again, if no specifications, then why
would you assume something will work only based upon an
arbitrary comment (such as high frequency capacitor). Once
numbers are provided, then surge protector does not even claim
to address your problem.

First confirm the power supply claims to provide a long list
of essential functions, or replace it. Cheap power supplies
can even contribute to damage of other computer components.

Randy wrote:
I've had this problem awhile but it seemed to be getting worse. My
computer pretty much wipes out my AM radio (FM unaffected). All the
wall sockets in my room are on the same circuit so I'm out of luck
moving the radio. Now... I expect the AM radio to go bonkers if the
system is on but this happens when the computer is off too. If I
switch the power supply to off in the back of the case all is well. Is
this normal?

The graphics board always has a light on (Radian 9600 pro) for the 8x
agp but I wouldn't think this would have that kind of affect. I hooked
the computer up to a belkin surgemaster with a high frequency
capacitor to no avail. I hooked my AM radio to the same surge
protector and again zippo.

Could the power supply be the culprit? If so are there ones on the
market anyone could recommend that wouldn't contaminate the AC line of
the house?

  #4  
Old July 23rd 03, 07:51 PM
Vanguard
external usenet poster
 
Posts: n/a
Default

"Randy" wrote in message
om...
I've had this problem awhile but it seemed to be getting worse. My
computer pretty much wipes out my AM radio (FM unaffected). All the
wall sockets in my room are on the same circuit so I'm out of luck
moving the radio. Now... I expect the AM radio to go bonkers if the
system is on but this happens when the computer is off too. If I
switch the power supply to off in the back of the case all is well. Is
this normal?

The graphics board always has a light on (Radian 9600 pro) for the 8x
agp but I wouldn't think this would have that kind of affect. I hooked
the computer up to a belkin surgemaster with a high frequency
capacitor to no avail. I hooked my AM radio to the same surge
protector and again zippo.

Could the power supply be the culprit? If so are there ones on the
market anyone could recommend that wouldn't contaminate the AC line of
the house?

Thanks

Randy


Sounds like you need a line noise filter for your AM/FM radio, like at
Radio Shack (http://tinyurl.com/htqm). However, I don't think you can
use it for your computer as its function is to eliminate line noise from
the input side, not getting introduced from the output side. All other
devices will also be affected by the noise that your computer power
supply is putting on the line, so you might want to plan for a better
power supply.


  #5  
Old July 23rd 03, 11:22 PM
w_tom
external usenet poster
 
Posts: n/a
Default

Filter is not unidirectional. However a filter superior to
that Radio Shack product must be inside the power supply. Too
many computer experts don't even have basic electrical
knowledge. Therefore many clone computers have power supplies
selected only on one specification - price. It is called the
MBA mentality. Inferior power supplies can be dumped into N
America at even greater profit because too many N American
technicians don't even know what a power supply is suppose to
do - never read specifications - don't even have basic
electrical knowledge.

They are called low pass filters. They work in either
direction. Nothing technically advanced about that electronic
knowledge. Would be nice if Radio Shack gave even one
specification other than price. But then this filter, like so
many computer power supplies, is also being recommended
without any technical knowledge - no number or specifications
need be provided.

Buy a power supply for $40 that is missing many essential
functions including that low pass filter. Then spend another
$40 for every other appliance to filter the noise. This is
why cost controller mentalities cause major cost increases.
Until a minimally acceptable power supply is installed, then
all other solutions are wasted money and time.

Minimally acceptable starts at about $80. If noise is not
quashed at the source, then every wire connecting to that
computer becomes a potential transmitting antenna.

Noise filter is not required. The problem first must be
fixed. Solution starts with specifications.

"Vanguard " wrote:
Sounds like you need a line noise filter for your AM/FM radio, like at
Radio Shack (http://tinyurl.com/htqm). However, I don't think you can
use it for your computer as its function is to eliminate line noise from
the input side, not getting introduced from the output side. All other
devices will also be affected by the noise that your computer power
supply is putting on the line, so you might want to plan for a better
power supply.

  #6  
Old July 23rd 03, 11:47 PM
jaster
external usenet poster
 
Posts: n/a
Default

Get a battery operated AM radio.

"Randy" wrote in message
om...
I've had this problem awhile but it seemed to be getting worse. My
computer pretty much wipes out my AM radio (FM unaffected). All the
wall sockets in my room are on the same circuit so I'm out of luck
moving the radio. Now... I expect the AM radio to go bonkers if the
system is on but this happens when the computer is off too. If I
switch the power supply to off in the back of the case all is well. Is
this normal?

The graphics board always has a light on (Radian 9600 pro) for the 8x
agp but I wouldn't think this would have that kind of affect. I hooked
the computer up to a belkin surgemaster with a high frequency
capacitor to no avail. I hooked my AM radio to the same surge
protector and again zippo.

Could the power supply be the culprit? If so are there ones on the
market anyone could recommend that wouldn't contaminate the AC line of
the house?

Thanks

Randy



  #7  
Old July 24th 03, 12:18 AM
rcm
external usenet poster
 
Posts: n/a
Default

That won't work. I try to run a battery one near the computer and getting
within 5 ft generates interference. It is frequency dependent so it is much
stronger in the lower AM band.

Use Internet radio to listen I guess.




"jaster" wrote in message
m...
Get a battery operated AM radio.



  #8  
Old July 24th 03, 12:56 AM
V W Wall
external usenet poster
 
Posts: n/a
Default

rcm wrote:

That won't work. I try to run a battery one near the computer and getting
within 5 ft generates interference. It is frequency dependent so it is much
stronger in the lower AM band.

Use Internet radio to listen I guess.


There are two kinds of RF interference, conducted (usually through the
power lines), and radiated, directly through the air. PC cases are
supposed to shield against radiated interference, but openings in the case,
poor contact between side panels, etc. can negate this. As w_tom says,
the PS should have line filtering for conducted noise. (The FCC requires
units sold in the US to pass tests for this.)

All switching power supplies generate RF interference over a
fairly wide band. Even when "off", the ATX PS has a stand-by supply
that is constantly on when line power is supplied to the unit.

Since a battery receiver still has problems, it is a radiated RF
signal that is the culprit. You might try a better ground on the
computer case than that supplied by the line cord. Check for any
openings other than those required for air flow, and make sure these
have metal grills.

Wrapping the receiver in aluminum foil grounded to a water pipe,
might be a brute force way of stopping it's reception of the PS
radiated energy. You would then need an external antenna connected
by a shielded co-ax, as someone has suggested.The PS generated noise
is usually at about 40Khz, but it has strong harmonics well into
higher bands.

Virg Wall
--
Be not the first by whom the new are tried,
Nor yet the last to lay the old aside.
  #9  
Old July 24th 03, 06:31 AM
Vanguard
external usenet poster
 
Posts: n/a
Default

Try to propose solutions that Randy can actually implement. Yes, he can
replace his power supply with a better unit. You're assuming he has
$80, or more, to waste on a new power supply AND that he is going to
install it rather than having to pay a shop to install it. Preaching
the best solution regardless of financial constraints doesn't help.
Others had already offered (or I expected others to offer) the high-road
solution, so I proffered a lower cost solution. I didn't say it was the
best solution. I just offered it as one possible solution and a
different one than the expected solution. There is no point to post a
"me-too" duplicate solution; a dozen replies of "get a better power
supply" doesn't give Randy many options for a solution. Of course,
another suggestion might be that Randy build a massive antenna with
active filtering and shielding just for his little AM radio but that
would be pointless without regard to Randy's financial, educational, and
physical constraints.

Ranting about the use of low-quality components as being a problem with
lack of education in techs regarding specifications doesn't help Randy,
either. It just illustrates that you are ****ed off about the situation
but also that you don't seem to realize that it is the consumers that
dictate the use of low-quality components in low-priced consumer-grade
computers. Buy cheap, get cheap. Wow, what a revelation. MacDonalds
and BurgerKing exist because there are enough consumers that want
low-priced low-quality food. Same for computers or any other product
where enough consumers are willing to sacrifice quality to get a cheap
price. The business of business is to stay in business so you sell to
whomever is willing to buy for whatever they want to buy at the price
they will pay. Using cheap power supplies has nothing to do with the
lack of education by techs but has everything to do with consumer
economics. Randy probably cannot effect a change in the industry or
influence a worldwide populace of consumers, so stop spewing farts at
him about problems in the industry (which is simply matching consumer
demands) or that these low-grade low-priced components don't follow
specs (since it is obvious to everyone that paying the lowest price does
NOT result in getting the highest quality).

You are also lambasting Randy that he has a cheap power supply.
Components (within components) do fail, so maybe his power supply was
okay but went bad and he needs to get a new one - but another one of the
exact same model might be just as good and resolve the problem without
having to waste money on a solution that far exceeds his requirements.
Your kid wants a wrist watch. Do you get him a $20 Timex or a
mega-grand Rolex? Both are solutions but obviously one fits better
within your financial constraints.

I expected other posters to state the obvious solution and Randy already
suspected the power supply, so I provided a different solution rather
than fixating on the most costly, most time consuming, and most
disruptive solution.


  #10  
Old July 24th 03, 07:02 AM
Vanguard
external usenet poster
 
Posts: n/a
Default

"rcm" wrote in message
. ca...
That won't work. I try to run a battery one near the computer and

getting
within 5 ft generates interference. It is frequency dependent so it

is much
stronger in the lower AM band.

Use Internet radio to listen I guess.


Since it is RF noise, I'm wondering if there is chance that it is not
the power supply but some other component inside the system unit that
causes the interference. Have you opened the case and unplugged the
power supply from the motherboard and other devices and then powered it
on to see if the noise reappears with just the power supply running?

Normally an ATX-style power supply will not turn on unless it is
connected to a motherboard. To test an ATX-style power supply without a
motherboard connection, short the PS-On signal (pin 14) to a ground
(pins 3, 5, 7, 13, 15, 16 or 17) in the 20-pin Molex connector; see
http://www.hardwaresite.net/faqpowersupply.html. Then you'll know if it
really is the power supply generating the noise or if some other
component, like a slot card, is causing the noise.

If running the power supply by itself produces no RF noise in your AM
radio, reattach the 20-pin Molex connector to the motherboard (with
power off, of course), leave all drives disconnected from power, and
remove all cards in the slots, even the video card. Power on (the boot
will fail due to the missing video card) to see if the noise is still
there. If not, power down, add a card (start with the video card), and
test again. If none of the cards are generating the noise, then start
hooking up the drives one at a time and test. What cards do you have
installed in the slots? Any tuner cards?

If you have a metal case, check that the grounding clips engage at the
bottom edges or wherever the cover slides onto the shell. If you don't
have any grounding clips to ensure the cover gets grounded to the shell,
I suppose you could try using aluminum foil folded over with enough
layers to wedge between the cover and shell but this would get damaged
when you next removed the cover and might not stay in place (I haven't
tried this so I don't know how well this works). I'm not sure what to
do if you have a plastic-only cover other than maybe spraying its inside
with metal conductive paint but that wouldn't survive much wear if you
frequently open your system unit.


 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Monitor Crackling Noise again Michael General 1 July 22nd 03 10:43 AM
NOISE Marc General 3 July 16th 03 05:33 PM
Antec PP-412X power supply fan making LOUD cricket noise! Excruciatingly annoying. Franklin Bowen General 0 July 15th 03 08:23 PM


All times are GMT +1. The time now is 04:35 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2022, Jelsoft Enterprises Ltd.
Copyright 2004-2022 HardwareBanter.
The comments are property of their posters.