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Modem fried and what else


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#1 earlgun

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Posted 03 September 2014 - 10:55 AM

Lightning hit my Gateway GT5012, Windows XP, thru the phone line.  Yes, I have dial up internet, very sad. My computer will not power up, but, there is a tiny green light lit up on the motherboard.  The modem board does have a small area that appears to be a dark (zapped) spot.  Replacing the modem board will be fairly inexpensive and easy enough to do (I hope).  Is it possible that a faulty modem board would keep the computer from powering on. 


Edited by hamluis, 03 September 2014 - 11:15 AM.
Moved from XP to Internal Hardware - Hamluis.


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#2 zingo156

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Posted 03 September 2014 - 11:59 AM

It is possible, pull the modem out if it is a pci card and try to power the computer on (unplug the power before pulling parts out). It is also possible the power supply took a hit so you can try with a different power supply if pulling out the modem does not change anything.

 

If the modem is built into the motherboard, then the motherboard may be damaged beyond repair.


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#3 rotor123

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Posted 03 September 2014 - 12:45 PM

I concur with Zingo, Follw that good advice.

 

I have seen dialup modems keep a computer from powering on.

 

FWIW there are brand name surge protectors that also include phone line protection. The good ones will also have insurance to cover damage caused by a surge that gets through their protection.

 

Good Luck

Roger


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#4 zingo156

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Posted 03 September 2014 - 12:47 PM

I saw one computer that had dial up with modem and it got hit by lightning while the family was on vacation. Luckily the computer was on a concrete floor. When they brought it in to the shop it was an unrecognizable piece of melted plastic and black. They wanted data from the drives, unfortunately those were also severely burned.


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#5 mjd420nova

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Posted 03 September 2014 - 07:03 PM

Yes, yank the modem card.  The modems have a specific and lengthy set of parameters that have to be met by the mfgrs of equipment hooked to a phone line.  One thing is a device called a spark gap and is to protect the rest of the hardware.  Unfortunatley it is a one time device and the card can't be repaired.  Modem cards(dial up) are getting close to obsolete but can still be found at swap meets, flea markets and garage sales.



#6 earlgun

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Posted 08 September 2014 - 08:04 PM

Thank you for your replies and suggestions.  My oops for posting in the wrong forum, I'll try to do better next time.

 

I did remove the modem (it did have some hot spots on it) and then tried to power up, w/ no luck.  Next, I removed the power supply and was about to put in a different one (from an older Compaq computer someone gave me - ATX 250-12Z rev. D), but, I'm not sure it's compatible.  I need to look closer at the various pin connectors. 

 

Do I have to re-connect all the power supply pin connectors, in order to verify the power supply is dead?  This is my first autopsy.  Thanks again.



#7 Joe C

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Posted 09 September 2014 - 06:30 AM

You can get a power supply tester, they used to be $10. but I guess you can chalk it up to inflation

http://www.newegg.com/Product/Product.aspx?Item=N82E16899261023&ignorebbr=1&cm_re=power_supply_tester-_-99-261-023-_-Product

 

If you do not want to buy a tester, you can take your power supply into a local pc shop and have them test it for you



#8 zingo156

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Posted 09 September 2014 - 07:11 AM

You do not have to connect all of them, just the 4pin and 20 or 24pin atx connections to the motherboard, with those connected it should turn on.


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#9 rotor123

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Posted 09 September 2014 - 09:02 AM

With the Power supply disconnected from the computer and the Power cord You can test a regular power supply by putting a jumper from the Green Pin on the 20 or 24 pin connector to an adjacent black pin. Then being careful not to let that jumper short anything else plug in the AC power. If the power supply fan does not run at that point the Power supply is dead. The Jumper from the green wire to the black turns the ATX power supplies on.

main24index.jpg
www.playtool.com

From the top left to right the pins are 13-24, the bottom from left to right are 1-12.

 

If it does turn on then This short tutorial by DC3

 

Reading PSU Rail Voltages

Caution: Please read this before continuing.


• Since it will be necessary for your computer to be on during this procedure, you need to be aware that you will be working with live 12Volt DC potentials, which if handled improperly may lead to electrical shock.

• There are electronics inside the case that are very susceptible to electrostatic discharges. To protect your computer, touch the metal of the case to discharge yourself of any electrostatic charges before touching any of the components inside.

• If you are not comfortable doing this procedure, then I would suggest that you not use this tutorial. The risks involved are minimal, but are there nevertheless. Anyone who uses this tutorial will be doing so at their own risk.


There are two devices commonly used to read the rail voltages: a PSU tester, and a multimeter.

The PSU tester is the easiest to use since all that is necessary is to plug the different connectors into the tester and read the results on the LCD display. The problem with most of these is that they only perform a pass/fail test. They will not provide you with actual voltage readings.

There are a variety of multiple meters, but this tutorial will address Analog and Digital multimeters. The advantage of these meters is that you will be able to obtain accurate real time voltage readings.

For those of you who wish to know more about multimeters there is an excellent article in Wikipedia.


Analog Multimeter

th_analogedited.jpg


An Analog multimeter is a little more complicated to use. Both Analog and Digital multimeters need to be set to the appropriate voltage, but with an Analog multimeter, you will need to choose the voltage range and must read the proper scale.

The Analog multimeter uses a needle display which moves from 0 across the scale until it reaches the voltage being tested. This multimeter has five major linear divisions with multiple scales to read a variety of ranges. An example would be three different ranges. The first is graduated in increments of 0 through 5, the second, 0 through 10, and the third, 0 through 25. Each of these ranges are subdivided into divisions that are graduated into tenths. In order to read 12 volts the 0 through 25 range would be the appropriate one.

Because DC voltage has positive and negative potentials this device is polar sensitive, this means that if you reverse the two probes when reading a positive DC voltage it will read as a negative voltage. This is actually necessary to read negative DC voltages. The two probes are differentiated by their color, Black (negative), and Red (positive). To read a positive DC voltage, the correct probes must be used with their corresponding potentials (positive to positive and negative to negative).

With the probes being used normally to read a negative DC voltage, the needle moves from the 0 to the left, "pegging" the needle. By reversing the probes you can properly read the negative voltages.

Digital Multimeter

th_digitalmeteredited.jpg


The Digital multimeter (DMM) is much simpler to use. As was mentioned previously, you will need to set the appropriate voltage. One of the advantages is that the DMM has an LCD display with a numeric readout, so there are not any multiple scales to read. Another advantage is that most DMMs are autoranging when reading voltages, which means that you will not need to set the range with these DMMs. A DMM will read both positive and negative DC voltages and display them correctly. When reading a negative voltage, a minus sign will appear on the display before the numeric value. This still is a polar sensitive device, so you will still need to use the positive and negative probes with their corresponding potentials.

There are five different DC rail voltages which are color coded. The Black wires are always negative.

Yellow +12VDC

Blue -12VDC

Red +5VDC

White -5VDC

Orange +3.3VDC


There are only three voltages that can be measured easily without disconnecting the 20/24 pin connector from the motherboard: +12V, +5V, and +3.3V.

The +12V and +5V voltages can be read from a four pin Molex power connector.

Four pin Molex power connector

th_250px-Molex_female_connector.jpg


The same voltages can be taken from a four pin SATA power connector, but in order to read the +3.3V you will need to read this from a five pin SATA power connector as seen below.

Five pin SATA power connector.

th_sata-power-cable.jpg

To read these voltages you will need to insert the Black (-) probe into any of the black sockets, and insert the Red (+) probe in the different colored voltage sockets. To read the voltages from a SATA power connector it is easiest to insert the probes into the back of the connector where the wires enter. Unfortunately the sockets of the modular SATA power connectors are not accessible from the back, so the readings will need to be made from the socket side. Some probes are going to be too large to fit in these sockets, so you may need to insert a piece of wire into the socket of which you want to read the voltage of and place the probe on this for your reading. To reduce the potential of creating a short I would suggest taking the ground potential from another connector so that the two wires will remain physically separated.

Caution: It is very important to make sure that you don't allow the two probes to touch each other when taking the voltage readings. This will cause a short which could damage the PSU or other components.

To get accurate readings of the rail voltages it is important that there be a load on the PSU. In order to do this I would suggest downloading Prime95 for this purpose. This program was designed to be used by overclockers to put a full load on the RAM and CPU to determine the stability of their overclocking. Because of this it will put stress on the CPU and RAM which will create higher than normal temperatures. For this reason I would suggest not running this program any longer than is necessary. I would also suggest that an inspection be made of the interior of the case to make sure that there isn’t an accumulation of dust which would impede adequate cooling. Pay special attention to the heat sink and fan assembly on the CPU. If there is a dedicated graphics card with a fan installed on it, look at this fan as well.


Readings should not have variances larger than +/- five percent.

Maximum.........Minimum
12.6V.................11.4V
5.25V.................4.75V
3.47V.................3.14V
 

 

Good Luck

Roger


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#10 earlgun

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Posted 09 September 2014 - 02:45 PM

Rotor 123, I tested the power supply with a jumper between the green wire and a black wire, on the 24 pin connector.  The fan did come on.  So, I am on to the next test.  I do have a digital multimater.   I plan to buy a power supply tester, but, don't have one yet, so, thanks for the 'work around tip'. 



#11 earlgun

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Posted 09 September 2014 - 03:34 PM

Joe C, there are plenty of pc shops advertised around this area, but, I do like the idea of testing 'what I can' myself.  So, I checked out the tester you referenced.  Price, etc. sounded good.  But, one of the negative reviews said that an outside 12v source was required in addition to the 24 pin connector or the tester would report a failure.  Sound right to you?  Somewhat confusing to me.  Thanks for the input.



#12 zingo156

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Posted 09 September 2014 - 03:37 PM

There is no need for an outside source, just plug in the 4pin and 20/24 pin atx connections and either a molex connection or sata connection from the psu to the tester and that will provide 12v. Maybe the person testing had a failed 12v rail and that is why they needed an outside source.


Edited by zingo156, 09 September 2014 - 03:38 PM.

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#13 rotor123

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Posted 09 September 2014 - 04:10 PM

The Main Problem with a Power supply tester and with just measuring at the pins is that some power supplies fail only under a load. I have seen that. Most power supply testers do not put a load on the different voltages. Not real surprising since that would add cost and complexity and have to be able to handle many different wattage supplies.

 

Good Luck

Roger

 

BTW in general the Wire colors and location are standardized red for one voltage, yellow for another. So If You see a power supply where the colors are located differently form the old one then one of them is non standard.


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#14 Joe C

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Posted 09 September 2014 - 04:39 PM

A volt meter puts no load on the power supply, so it's about the same as your suggestion, only much easier and safer to use the power supply tester because it's designed to measure voltages and the Power Good signal too, which would be difficult to measure milliseconds of volts with a volt meter



#15 rotor123

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Posted 09 September 2014 - 05:57 PM

A volt meter puts no load on the power supply, so it's about the same as your suggestion, only much easier and safer to use the power supply tester because it's designed to measure voltages and the Power Good signal too, which would be difficult to measure milliseconds of volts with a volt meter

 

Hi Joe

True, However the OP has a Digital Multimeter and thus no extra cost. If one of the voltages is off or missing, Then that defines bad power supply.

 

Roger


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