Pentium 133 system won't POST

[f1lm]

I've recently come into possession of an immaculate Micron Pentium Classic 133 desktop PC, and I've been trying to do a refurb and set it up for some DOS gaming and internet browsing.

The last part is when the problem came in. I installed a Compaq NC3122 dual Ethernet NIC card, and couldn't get drivers for it because I didn't have a Win98 disk. After that, I removed the card and tried a SCSI/Ethernet controller combo card. The PC wouldn't post, and the monitor was pitch black.

I took the SCSI card out, and the PC still refused to POST. I then proceeded to switch the GPU, CPU, HDD, just about everything, and I even reseated everything.

Still no POST.

Anyone have an idea what's going on with it? It seems to have to do with either the Compaq Ethernet card or the SCSI/Ethernet combo card that I put in it. I'd really like to see this thing running again, and any help would be appreciated.

 

[modem7]

Does it POST with only motherboard/PSU/video present?
Also, try clearing the CMOS/SETUP RAM by removing the battery for a few minutes.

 

[f1lm]

Does it POST with only motherboard/PSU/video present?
Also, try clearing the CMOS/SETUP RAM by removing the battery for a few minutes.

Nope, it refuses to POST no matter what I do.

The system doesn't actually have a CMOS battery, just a real-time clock chip like the one below that I assume is related to the CMOS functions, since there is no battery of any kind present.

I've tried removing this, even replacing it with another one, and the thing still refuses to do anything.

I don't know if this makes a difference, but it uses an AT power supply.

 

[Agent Orange]

Nope, it refuses to POST no matter what I do.

The system doesn't actually have a CMOS battery, just a real-time clock chip like the one below that I assume is related to the CMOS functions, since there is no battery of any kind present.

I've tried removing this, even replacing it with another one, and the thing still refuses to do anything.

I don't know if this makes a difference, but it uses an AT power supply.

Does the power supply come on? Check to see if the fan is spinning. Also, when you were swapping boards in and out, check to see if any of the card slots have a bent pin.

 

[f1lm]

PSU comes on fine, so do the lights. The HDD LED isn't stuck on, and everything when it starts up is normal, except the fact that the monitor doesn't give any video after the HDD self-tests like it normally does.

Never did check the card slots, though. Can PCI even get bent pins from normal card removal?

EDIT: Checked the slots, no bent pins of any kind.

 

[NathanAllan]

Is it possible the processor is not working? I would see about replacing it, but first...

Since it has a Dallas RTC have you let it sit for a time, so it can charge up? That can also cause a (rare) non-post.

But definitely check the main processor. Is the heat sink on good? Does it have a dedicated fan or just a passive oversized heat sink? Does it look like it might have slipped off and been put back on, with tell-tale scratches on the bracket (from using a screwdriver to put it on or off)?

 

[Chuck(G)]

Pardon a silly question, but...

When you were removing the cards, you didn't happen to drop your screwdriver on the motherboard, did you? I'm not being silly--I once did that--and it was a small screwdriver--and all of the PCI slots quit working. A detailed examination with a jeweler's loupe disclosed that I'd severed one of the very fine traces on the board.

When you power up, do your keboard lights blink briefly as it's reset?

Try pulling all of the DRAM and expansion cards out and powering it up--see if you get the "no memory" beep out of the speaker.

 

[kishy]

Not meaning to discredit NathanAllen but I've never heard of a "charging up" time on the Dallas RTCs. I certainly haven't worked with them in volume, only a few machines with them, but in both the cases where I installed a new one or hacked it apart and replaced the battery alone, it immediately worked as expected within minutes (perhaps under a minute) of the swap. In the case of dead ones (battery only, other bits still operational) the system functions as normal except for being unable to retain any settings. In addition to that, the battery is not rechargeable, so it does not need to be charged by the system if that's what was meant.

For the sake of clarity...did it appear to be operating completely properly before the symtoms showed up? Failure to POST after the installation and subsequent removal of an expansion card (in particular, not a video card) is, in my perhaps limited experience, usually a sign of problems that aren't going away any time soon.

Edit: definitely seconding Chuck's suggestion about RAM. If it won't issue a beep code (this presumes you have a system speaker) then something rather important is simply not working.

Edit again: perhaps best not to mention this, because you could try it and destroy something (and it is REALLY not a good idea), but I was able to get a machine from this point to properly operational again by repeatedly assaulting the power switch until it eventually POSTed. I was thoroughly expecting it to self destruct instead, though. In that case the power supply would seem to have been the issue...

 

[MV75]

Standard troubleshooting:

Take mainboard out of case, put on anti static bag and plug in a known working power supply, vid card and 2 sticks (72pin assumed), of memory.

The scsi card could have fudged the bios too. Is it going into recover mode? Reading floppy?

The dallas has a lithium batteries in it. Read more info here on it: http://www.hardwaresecrets.com/printpage/Replacing-the-Motherboard-Battery/81

 

[f1lm]

Excuse the wall of text and quotes, but I'd rather not do a multi-post response.

Is it possible the processor is not working? I would see about replacing it, but first...

Since it has a Dallas RTC have you let it sit for a time, so it can charge up? That can also cause a (rare) non-post.

But definitely check the main processor. Is the heat sink on good? Does it have a dedicated fan or just a passive oversized heat sink? Does it look like it might have slipped off and been put back on, with tell-tale scratches on the bracket (from using a screwdriver to put it on or off)?

I've gone through three known good Pentium CPUs. The heatsink is a fan, and it's pretty firmly mounted on it, doesn't look like it's coming off without some force.

Pardon a silly question, but...

When you were removing the cards, you didn't happen to drop your screwdriver on the motherboard, did you? I'm not being silly--I once did that--and it was a small screwdriver--and all of the PCI slots quit working. A detailed examination with a jeweler's loupe disclosed that I'd severed one of the very fine traces on the board.

When you power up, do your keboard lights blink briefly as it's reset?

Try pulling all of the DRAM and expansion cards out and powering it up--see if you get the "no memory" beep out of the speaker.

I actually went screwless when I installed that card, but that might've happened.

When I power the rig up, the keyboard lights will flash briefly, and all of the lights connected to the motherboard will come on, but the thing won't issue any POST beeps of any kind. I forgot to mention this in my original post, for some reason.

I've tried powering it on with nothing in it, still no luck.

Not meaning to discredit NathanAllen but I've never heard of a "charging up" time on the Dallas RTCs. I certainly haven't worked with them in volume, only a few machines with them, but in both the cases where I installed a new one or hacked it apart and replaced the battery alone, it immediately worked as expected within minutes (perhaps under a minute) of the swap. In the case of dead ones (battery only, other bits still operational) the system functions as normal except for being unable to retain any settings. In addition to that, the battery is not rechargeable, so it does not need to be charged by the system if that's what was meant.

For the sake of clarity...did it appear to be operating completely properly before the symtoms showed up? Failure to POST after the installation and subsequent removal of an expansion card (in particular, not a video card) is, in my perhaps limited experience, usually a sign of problems that aren't going away any time soon.

Edit: definitely seconding Chuck's suggestion about RAM. If it won't issue a beep code (this presumes you have a system speaker) then something rather important is simply not working.

Edit again: perhaps best not to mention this, because you could try it and destroy something (and it is REALLY not a good idea), but I was able to get a machine from this point to properly operational again by repeatedly assaulting the power switch until it eventually POSTed. I was thoroughly expecting it to self destruct instead, though. In that case the power supply would seem to have been the issue...

The PC was working perfectly fine before the symptoms occured. No issues whatsoever. And then after I removed that NIC and replaced it with the SCSI card, the thing stopped POSTing, not even giving out beep codes.

Standard troubleshooting:

Take mainboard out of case, put on anti static bag and plug in a known working power supply, vid card and 2 sticks (72pin assumed), of memory.

The scsi card could have fudged the bios too. Is it going into recover mode? Reading floppy?

The dallas has a lithium batteries in it. Read more info here on it: http://www.hardwaresecrets.com/printpage/Replacing-the-Motherboard-Battery/81

The thing doesn't do anything but light up when I turn it on. I haven't tried removing the motherboard, because I'm lacking an empty AT case to test with, but nothing has happened to the PSU at all in the small amount of time that I've been working with it.

 

[MV75]

No, when I say remove from case, just that, take it out of the case and put it on an anti static bag. This eliminates any shorts that may be caused by movement and the case itself.

I'm then sure you'll find a way to get the motherboard power headers from the case to the motherboard. Either from some clever case positioning, or removing the power supply from the case.

Also try different slots with video card and different video cards. And since it'll be in "bench test" mode, make sure the video card is more or less straight in the slot. And give the board and jumpers a double check as I don't know what board you have, nor how you remove cards, a jumper could have been flicked off.

 

[Chuck(G)]

When I power the rig up, the keyboard lights will flash briefly, and all of the lights connected to the motherboard will come on, but the thing won't issue any POST beeps of any kind. I forgot to mention this in my original post, for some reason.

I've tried powering it on with nothing in it, still no luck.

This is not good, not good at all. You could try this, as another poster has suggested, with the board out of the case and with nothing but the power supply and speaker connected. A sheet of plywood is about as static-free as an anti static bag (softwood absorbs moisture and so tends to resist static buildup).

Something got zapped in process of your changes and now the task gets much more difficult. When you have the mobo out of the case, go over it with a magnifier f you have to, just to make sure that you didn't nick or bump something. You could also have a marginal (cold) solder connection or cracked trace.