insulators needed under mobo's mounting screws?

[RS]

I am repairing a computer that has a AOpen Slot 1 motherboard that won't
boot. (The CPU tests OK on another system, as does the RAM)

I have purchased a used ASUS Slot 1 motherboard off of eBay. I am now in the
process of swapping the motherboards and I see that the old motherboard has
pieces of black electrical tape on the bottom where the mounting screws poke
through. Is this necessary? I know that bags of hardware that comes with
computer cases used to (I recall) include little brown "paper" washers.

Thanks for any knowledgeable opinions / clarification !

-RS-

 

[sooky grumper]

I am repairing a computer that has a AOpen Slot 1 motherboard that won't
boot. (The CPU tests OK on another system, as does the RAM)

I have purchased a used ASUS Slot 1 motherboard off of eBay. I am now in the
process of swapping the motherboards and I see that the old motherboard has
pieces of black electrical tape on the bottom where the mounting screws poke
through. Is this necessary?
no

I know that bags of hardware that comes with
computer cases used to (I recall) include little brown "paper" washers.

Thanks for any knowledgeable opinions / clarification !

-RS-

 

[RS]

Thanks ! Some other people have suggested that the
paper-washers-on-mounting-screw thing dates back to AT Power Supply days.

FYO:
((The old motherboard was an AOpen MX6E PLUS which has an Intel 440EX
chipset. ))
((The new one is an Asus P2B-F which has an Intel BX chipset.))

But now I have a different problem: I have printed off the 80 page PDF
manual from Asus's site ... and have installed the motherboard; set the
jumpers to the proper bus speed and multiplier; installed the CPU and 2
sticks of memory (128mB total) ; installed just one card - the PCI video
card; connected the PS power plug to the mobo ...and hooked up most of the
control leads like reset, power SW leads to mobo, speaker, etc. leads. But
what happens when I turn on the Power Supply's switch (at the back) is the
following:

- unit powers up without waiting for me to press the power-on button on the
front of the tower
- Keyboard's 3 lights flash once on momentarily
- no beep or anything from speaker
- CPU fan operates.
- nothing shows on the monitor ... it's green LED continues to flash from
time to time like it is in sleep mode.

Based on the above symptoms, what is the general consensus as to what is
wrong?

Thanks !

-RS-

 

[gothika]

You can use nylon flat washers as insulators.
The better computer shops sell hardware packs that have these neat
little nylon standup spacers with insulator sleeves that can isolate
the board from the metal of the chassis.

 

[Patrick]

Thanks ! Some other people have suggested that the
paper-washers-on-mounting-screw thing dates back to AT Power Supply days.

FYO:
((The old motherboard was an AOpen MX6E PLUS which has an Intel 440EX
chipset. ))

Are you ABSOLUTELY SURE that the Aopen power supply has the standard
wiring, and is in good order, meeting PC specifications? (Some
proprietary Power Supplies, such as Compaq, switch around the wiring!
Not sure about Aopen, but, I had tried to switch out an Aopen board,
with another brand mainboard, and ended up getting a new case and PSU,
before the computer would work!).

((The new one is an Asus P2B-F which has an Intel BX chipset.))

Did you pull the bios battery, so that the CMOS resets to factory specs.?
Incorrect CPU settings in CMOS can conflict with board jumpers so that
nothing comes up, clock never starts.

But now I have a different problem: I have printed off the 80 page PDF
manual from Asus's site ... and have installed the motherboard; set the
jumpers to the proper bus speed and multiplier; installed the CPU and 2
sticks of memory (128mB total)

Try it with only minimal memory, in only one DIMM slot.
Make sure it meets the speed requirements (100 Mhz?)


; installed just one card - the PCI video

card;

If it has an AGP slot, do NOT install the PCI video card in the adjacent
PCI slot (sometimes 'shared' with AGP).

connected the PS power plug to the mobo

Plug it in very firmly, make sure it is not cocked...
...and hooked up most of the

control leads like reset, power SW leads to mobo, speaker, etc. leads.

Double check all the connections...

But what happens when I turn on the Power Supply's switch (at the back) is the
following:

- unit powers up without waiting for me to press the power-on button on the
front of the tower
- Keyboard's 3 lights flash once on momentarily
- no beep or anything from speaker
- CPU fan operates.

You have the 12Volts, (fan on board) but, evidently, NOT the 5 Volts
that mostly powers the CPU, system clock,PCI bridge (SouthBridge) and
Memory, Voltage regulators.
Have four of that ASUS mainboard here, plus two each P2B-DS,
P2L97-DS266, CUV-4DS boards. Very hardy stuff, very reliable!

 

[Stacey]

You can use nylon flat washers as insulators.
The better computer shops sell hardware packs that have these neat
little nylon standup spacers with insulator sleeves that can isolate
the board from the metal of the chassis.

Why would you do that? Just wondering....

 

[Matt]

I am repairing a computer that has a AOpen Slot 1 motherboard that won't
boot. (The CPU tests OK on another system, as does the RAM)

I have purchased a used ASUS Slot 1 motherboard off of eBay. I am now in the
process of swapping the motherboards and I see that the old motherboard has
pieces of black electrical tape on the bottom where the mounting screws poke
through. Is this necessary? I know that bags of hardware that comes with
computer cases used to (I recall) include little brown "paper" washers.

Thanks for any knowledgeable opinions / clarification !

-RS-

Why would mobo makers put metal circles around the mobo screw holes if
they didn't want the mobo to be grounded to the chassis?

 

[Overlord]

Why would mobo makers put metal circles around the mobo screw holes if
they didn't want the mobo to be grounded to the chassis?

The little metal circles, sometimes with solder blobs on them are of course to ground
that part, and only that part to the chassis. The spacer part of it comes in to play to make
sure that everything else on the backside of the MB doesn't ground out too.

I believe the little fiber washers mostly came into play back when the mounts on the
chassis for the motherboard were raised dimples. They were wider than they needed
to be, and the MB manufacturers were occasionally a little more.... freehanded mounting
components on the board near the mounting holes. They may have played a very minor
role in vibration/stress dampening.

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[Guest]

Why would mobo makers put metal circles around the mobo screw
holes if they didn't want the mobo to be grounded to the chassis?

The problem is motherboard makers don't always put metal circles
around every screw hole, and it's possible to short the board at such
holes. So each hole has to be checked on top and bottom for either
this or, if the hole doesn't have a metal circle, for sufficient
clearance between the hole and the closest copper, which may be
carrying a signal or voltage supply. When in doubt, insulate, and
rely upon the motherboard power connector(s) and plug-in card rear
brackets for rounding.

Electrical tape makes a poor insulating material because a screw or
mounting post can easily pierce it. Satisfactory insulator washers
are made of cardboard (fiber), nylon, or Mylar (Mylar must be
translucent, not so thin that it's transparent).

 

[Guest]

You can use nylon flat washers as insulators.
The better computer shops sell hardware packs that have
these neat little nylon standup spacers with insulator
sleeves that can isolate the board from the metal of the
chassis.

That hardware is also available from electronic supplies and hardware
stores (smaller ones, not home centers), often for less than computer
store prices. I'm not sure what nylon standup spacers with insulator
sleeves are, but there are nylon standoffs made for circuit boards,
and most snap into the board. Nylon hex spacers are also available
with threaded holes, and nylon screws can be used with them.

 

[Guest]

You can use nylon flat washers as insulators.
The better computer shops sell hardware packs that have
these neat little nylon standup spacers with insulator
sleeves that can isolate the board from the metal of the
chassis.

That hardware is also available from electronic supplies and hardware
stores (smaller ones, not home centers), often for less than computer
store prices. I'm not sure what nylon standup spacers with insulator
sleeves are, but there are nylon standoffs made for circuit boards,
and most snap into the board. Nylon hex spacers are also available
with threaded holes, and nylon screws can be used with them.

 

[Guest]

I am repairing a computer that has a AOpen Slot 1 motherboard
that won't boot. (The CPU tests OK on another system, as does
the RAM)

I have purchased a used ASUS Slot 1 motherboard off of eBay.
I am now in the process of swapping the motherboards and I see
that the old motherboard has pieces of black electrical tape
on the bottom where the mounting screws poke through. Is
this necessary? I know that bags of hardware that comes with
computer cases used to (I recall) include little brown "paper"
washers.

I believe the AOpen motherboard, which, by the way, does use a
standard ATX power connector, not a proprietary one, was installed
improperly by the previous owner because electrical tape is a poor
insulator when exposed to high pressure (such as from motherboard
mounting screws) or sharp edges (such as from screws or brass standoff
posts), and it may have gradually been pierced and shorted the
motherboard to the chassis. Those brown paper washers are much better
for this application, as are Mylar washers (translucent, creamy white
or yellow only, not the much thinner transparent ones) and the nylon
washers mentioned by Gothika.

Motherboards are supposed to be designed so they cannot possibly short
to the chassis, whether or not insulator washers are used, but in
reality this isn't always so, and I've seen holes where copper signal
traces or even large copper areas connected directly to a power supply
voltage ran close enough to cause shorts. Therefore you must inspect
each mounting hole and not make any assumptions. If a hole has a
copper ring around it (that copper is usually coated with solder) or
has no metal within at least 1/8" - 3/16" of its circumference, then
no insulator washer is needed -- for that particular side of the hole.
When in doubt, install an insulator because it won't do any harm,
unlike a short.

Older computers did not use stamped risers (raised dimples) for
mounting the motherboard but instead had brass mounting posts screwed
to them from the bottom or rails spot welded in place with slots into
which nylon standoffs could slide. Stamped risers weren't introduced
in computer cases until they became cheapened and made of thinner
metal, but even brass mounting posts, despite being narrower than
risers, still often need insulator washers on them.

 

[Guest]

I am repairing a computer that has a AOpen Slot 1 motherboard
that won't boot. (The CPU tests OK on another system, as does
the RAM)

I have purchased a used ASUS Slot 1 motherboard off of eBay.
I am now in the process of swapping the motherboards and I see
that the old motherboard has pieces of black electrical tape
on the bottom where the mounting screws poke through. Is
this necessary? I know that bags of hardware that comes with
computer cases used to (I recall) include little brown "paper"
washers.

I believe the AOpen motherboard, which, by the way, does use a
standard ATX power connector, not a proprietary one, was installed
improperly by the previous owner because electrical tape is a poor
insulator when exposed to high pressure (such as from motherboard
mounting screws) or sharp edges (such as from screws or brass standoff
posts), and it may have gradually been pierced and shorted the
motherboard to the chassis. Those brown paper washers are much better
for this application, as are Mylar washers (translucent, creamy white
or yellow only, not the much thinner transparent ones) and the nylon
washers mentioned by Gothika.

Motherboards are supposed to be designed so they cannot possibly short
to the chassis, whether or not insulator washers are used, but in
reality this isn't always so, and I've seen holes where copper signal
traces or even large copper areas connected directly to a power supply
voltage ran close enough to cause shorts. Therefore you must inspect
each mounting hole and not make any assumptions. If a hole has a
copper ring around it (that copper is usually coated with solder) or
has no metal within at least 1/8" - 3/16" of its circumference, then
no insulator washer is needed -- for that particular side of the hole.
When in doubt, install an insulator because it won't do any harm,
unlike a short.

Older computers did not use stamped risers (raised dimples) for
mounting the motherboard but instead had brass mounting posts screwed
to them from the bottom or rails spot welded in place with slots into
which nylon standoffs could slide. Stamped risers weren't introduced
in computer cases until they became cheapened and made of thinner
metal, but even brass mounting posts, despite being narrower than
risers, still often need insulator washers on them.

 

[yogi]

If you computer wont boot and you are sure that the other components
are working properly, then I don't see any problem giving the fibre
washers a try, I had a P4S8X-X motherboard that would not boot because
it could not find the IDE drives, I took it back to where I purchased
it but they said that the errors I was getting did not indicate that
the board was at fault and told me to set the motherboard up out side
the case, so I did that and it worked, so I put the computer back
together and it would not work again so I put fibre washers under the
screw heads and all was well.
Cheers

Why would mobo makers put metal circles around the mobo screw holes if
they didn't want the mobo to be grounded to the chassis?

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[Conor]

Why would mobo makers put metal circles around the mobo screw holes if
they didn't want the mobo to be grounded to the chassis?

THey're not connected to anything therefore they're grounding nothing.

They're there solely to prevent you tightening it so much that you chew
the screwhead into the PCB or is that too simple an explanation?

 

[Conor]

The little metal circles, sometimes with solder blobs on them are of course to ground
that part, and only that part to the chassis. The spacer part of it comes in to play to make
sure that everything else on the backside of the MB doesn't ground out too.

That makes no sense whatsoever as it'd still be connected electrically.
The spacers are there to prevent damage to the motherboad. Some screws
I have here have a serated face at the bottom side of the screw head.

 

[Conor]

The problem is motherboard makers don't always put metal circles
around every screw hole, and it's possible to short the board at such
holes.

ROFL...the bullshit coming out of this thread is unreal.

Circuit board layouts are designed so that there is a clear area around
the screwholes so this cannot happen.

 

[Guest]

ROFL...the bullshit coming out of this thread is unreal.

Circuit board layouts are designed so that there is a clear
area around the screwholes so this cannot happen.

That makes no sense whatsoever as it'd still be connected
electrically. The spacers are there to prevent damage to the
motherboad. Some screws I have here have a serated face at
the bottom side of the screw head.

THey're not connected to anything therefore they're grounding nothing.

Have you actually taken resistance measurements? I have, and I found
that most metal rings were connected to ground. Which motherboards
have no electrical connection between those rings and anything else?

About every other motherboard I've seen had at least one mounting hole
with signal or voltage traces running close enough to make possible a
short, especially if the case uses risers instead of standoffs or if
the screw heads are wide.

 

[FoneClone]

That makes no sense whatsoever as it'd still be connected electrically.
The spacers are there to prevent damage to the motherboad. Some screws
I have here have a serated face at the bottom side of the screw head.

[nothing to add to discussion -- just wanted to compliment Conor on
his outstanding "shit list" sig]

 

[Overlord]

That makes no sense whatsoever as it'd still be connected electrically.
The spacers are there to prevent damage to the motherboad. Some screws
I have here have a serated face at the bottom side of the screw head.

I don't follow what you're trying to say.

The underside of the head of the screw is supposed to contact the metal rim of the mounting
hole to make an electrical connection to the chassis ground of the case.

The "spacer" I'm referring to is on the underside of the motherboard.
It "spaces" the rest of the mb away from the chassis ground of the case.

If you believe it makes no difference, since you're "connected electrically" anyway.
Then by all means lay your next motherboard flat on the mounting plate without spacers on the
underside and with all the soldered leads on the underside of the motherboard laying against the
metal plate, screw it down, and power it up.

We'll see how electrically connected you can get.
We'll see how much sense it makes to keep the underside of the MB from being grounded out
across the board.

I've seen you post before Conor. Please don't post when you're too tired to make sense of
what's already written....
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