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Assembling one PC, system won't start.

Posted on 1998-12-29
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Last Modified: 2010-04-27
I'm assembling one PC (PT-2011 ATX mobo. with a 233 Mhz MMX CPU). After carefully configuring and putting everything together, I turned the machine on. The system starts for a few seconds (you can hear the HDD running), then kind of stops (no spinning sound) and the monitor displays "Missing signal". I checked everything again, retried and the same happpened.
Could it be that some parts are defective, like the power supply or the mobo.itself?. I exchanged the mobo., got an identical one, asssembled the parts and did the configuration. Same thing.
One thing I noticed: the case does not have a cable for the keyboard, as the mobo. indicates, to allow the keyboard access the system. Supposedly this cable should be in the bundle of thin cables coming from the front panel.
Could this be part of the problem?.
TIA for any help from the experts, I really need to solve this issue ASAP.
Regards.

Efrain R Portales
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Question by:efrain12
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by:syzygy
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First thing to try is Video card....  reseat it, and if at all  possible try another one.

The keyboard lock is nothing to worry about... it's just a way of locking the keyboard so it can be used.  


Another thing:  try removeing all non-essential components, leaving only th evideo card in.
(this includes dissconnecting HDD and CDROM)

reseat memory and CPU.  Any components you can test by trying in a different system or trying other parts, do so.


Try shorting out the jumper on the mother board where the switch connects... sometimes a faulty power switch can cause problems.

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by:cheekycj
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I would definitely try what syzygy stated in first trying to make it work with
just the video card and if you have problems still- work the cpu and memory issues-
try new(alternative) mem or CPU if possible (from a friend maybe?)

Also when you put the video card in make sure it isn't shortcircuiting the MotherBoard
ie- touching the motherboard at a wrong spot or touching the case (its a weird thing
and hard to explain- just make sure that the video card is seated properly and
not awkwardly)

Have you thought it may be a faulty Video card itself.  I have run across such problems
with ATI cards.

Let us know what you find out.

CJ
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mark2150 earned 50 total points
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"No signal" is monitor generated message saying no video is present. However, the video card itself being bad would generate POST beeps. If you're not getting a POST beep then problem is deeper in system.

Strip system down to powersupply, MB, CPU, RAM & speaker. Fire it off and listen for POST beeps. No beeps at this point says CPU/RAM/MB is DOA. Check powersupply outputs too. +5 on red, +12 on yellow +-5%.

Pull CPU (are you using anti-static handling?) & check for bent pins, etc.

Pull RAM & clean contacts with green side of dollar bill (this will remove contamination and not gold plating). Reseat CPU and RAM and repeat test. Still failing, swap CPU & RAM with "known good" system. Still failing - replace MB.

HD will spin up as soon as +12 is applied to motor.

MB should complain via POST beeps if keyboard/video is not present. No POST beeps, sick system. If you can get a series of beeps in the stripped config then add video card and retest. That works, then plug in HD and retest.

Give system a good visual inspection under a strong light. Make sure that everything that is in a socket is down tight. Look for bent pins, etc.

M


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by:efrain12
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Thanks for your prompt replies.
Like I said, this is the second mobo I try, so, it'd be very uncommon that the mobo itself is bad. Could it be that the mobos are shorted because of the way I fix them to the metal support?.
Since I didn't get specific instructions, I've done it the way I've seen pictures on books and on other systems I've had.
Basically, I attach the mobo with four special fasteners (with male and female threads) that go between the mobo and the supporting plate, then I place the screws on top of the mobo to fix it to the metal plate with those fasteners; in addition to this, I use plastic clips inserted from behind the metal plate, to give additional support.
Could it be that this is causing a short?, if so, what else am I missing? (no other fasteners were supplied).
If no beeps are heard, could it be the speaker is not connected correctly?. The pins were the front panel cables connect don't show the way to insert the connector(which is a four-pin connector with only two wires: red and black).
One more thing: when I try to turn off the system with the front panel button, it stays on. I have to turn the syst. off from the surge protector. BTW, I insert this connector (called "Remote Power switch" on the manual)on the pins indicated on the instructions, but again, there's no indication on the way to make the connection.
Please add any comments that may help me make the system work.
Regards.

Efrain R Portales
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by:mark2150
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Normally there is only *ONE* metal support, back in the rear by the keyboard connector. ALL OTHERS should be on plastic stadoffs.

You can tell a spot that is expecting a metal support post, the PCB will have a large, open pad for the screw and post to land on. If the MB has clear green overcoat where the post is (from the bottom side) then DO NOT PUT A POST THERE!

Test is, of course, to fire up *NAKED BOARD* on piece of cardboard or somesuch before installing into case. If it works there and fails when installed then you're doing it wrong!

M

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by:syzygy
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If the system wontturn off, try hold the button in for 10 seconds... this should force an ATX system to shut down.
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by:syzygy
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If the system wontturn off, try hold the button in for 10 seconds... this should force an ATX system to shut down.

If I'ts not shutting down, it may be the power supply.  Unfortunatly ATX supplys are a little tricky to test.  they should always trickle a little voltage out to the MBD, even when off, and put out the 5/12 volts to things like HDDS only when on.  Do you have a multimeter to try testing this?


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by:efrain12
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Hi guys,
Thanks for your replies. You both were right about trying a barebones system and testing with different devices.
I fixed the problem (MOF, I'm writing from my new baby!), know what it was?: The memory chip !!. It was bad. I replaced it with another one from my main PC, problem solved !.
Hopefully, I didn't short the mobo, and everything went ok.
Thanks again, to you and to this wonderful place for the computing community !.
Feliz Año Nuevo!(Happy New Year !).

Efrain R Portales.
P.S.
To mark2150: I'm curious, what does " DOA " mean?, Dead On ...?
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by:cheekycj
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DOA means Dead on Arrival.

CJ
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by:efrain12
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Thanks CJ.

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