[comp.sys.ibm.pc.hardware] fried motherboard?

heiser@tdw201.ed.ray.com (08/10/90)

In the process of building a new machine, I think I did something REALLY
dumb.  I am putting a 386/25 board in a tower case, and basically 
followed the way the m/b in my AST 286 was set up.  That is, on the 
motherboard, where the screws go thru, there were metallic areas ... it
appears that AST has the motherboard grounded to the chassis.

Well, I went along with this idea, and did the same on my 386 board in
the tower case.  When I powered the machine up, the power supply fan
wouldn't even start!  It appeared that maybe something was shorted out.
Anyway, I rummaged thru the ahrdware that came with the case, and found
some fiber washers.  I then re-installed the mb, using the washers to
insulate it from the chassis.  Now the system fires up, but the mb
seems brain-damaged.  When running thru the ram check, it goes VERY
slowly...  even when hard-jumpered into turbo mode.  

Once the system is up (it beeps a few times along the way, but does boot
up, but only from a floppy -- it times out tryin to reach the disk), I
ran the landmark test ... and it shows the system performing "normally" 
(the same as it did when I tested it in my 286 case).  When I run a 
progrma (called "t.com") that tests the cpu speed, it shows it at much
below what it should be (but this program worked before).

My question is this:  what did I probably damage by shorting out the mb?
Should I try to just send the whole thing back to NJ for replacement and
live without it for a couple of weeks or whatever it take s to get it (or
a replacement) back?  Should I try to replace some specific part on the
board?

Thanks for your comments.

Bill

-- 
Bill Heiser
	Work:   heiser@tdw201.ed.ray.com
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cy5@cunixa.cc.columbia.edu (Conway Yee) (08/11/90)

In article <2051@sud509.ed.ray.com> heiser@tdw201.ed.ray.com writes:
>In the process of building a new machine, I think I did something REALLY
>dumb.  I am putting a 386/25 board in a tower case, and basically 
>followed the way the m/b in my AST 286 was set up.  That is, on the 
>motherboard, where the screws go thru, there were metallic areas ... it
>appears that AST has the motherboard grounded to the chassis.
>
>Well, I went along with this idea, and did the same on my 386 board in
>the tower case.  When I powered the machine up, the power supply fan
>wouldn't even start!  It appeared that maybe something was shorted out.
>Anyway, I rummaged thru the ahrdware that came with the case, and found
>some fiber washers.  I then re-installed the mb, using the washers to
>insulate it from the chassis.  Now the system fires up, but the mb
>seems brain-damaged.  When running thru the ram check, it goes VERY
>slowly...  even when hard-jumpered into turbo mode.  
>
>Once the system is up (it beeps a few times along the way, but does boot
>up, but only from a floppy -- it times out tryin to reach the disk), I
>ran the landmark test ... and it shows the system performing "normally" 
>(the same as it did when I tested it in my 286 case).  When I run a 
>progrma (called "t.com") that tests the cpu speed, it shows it at much
>below what it should be (but this program worked before).
>
>My question is this:  what did I probably damage by shorting out the mb?

It doesn't really matter.  As long as the board does not work send it
back.  If it happens that it is NOT the motherboard, oh well.  Not your
problem.

>Should I try to just send the whole thing back to NJ for replacement and
>live without it for a couple of weeks or whatever it take s to get it (or
>a replacement) back?  

Yes.  The darned thing is under warranty.  Let your vendor sort it out.
Remember to swear on a stack of bibles that
	1) you did nothing wrong.
	2) you tried to replace everything else and it checks out OK.
	   Thus, it must be their fault.  They sent a fried board.
Be sure to stand firm and insist on returning it.  Sometimes the sales
people get to be real assholes when it comes to returns.

>Should I try to replace some specific part on the
>board?

Forget that idea.  First, it would void your warranty. Second, how are 
you going to locate the specific fried chip without a ton of testing
equipment?  Third, it will take a heck of a long time to figure it out.
I don't know about you but my time is more valuable than that.  You
paid your vendor for the privilege of returning defective goods.  Use it.

			Conway Yee, N2JWQ

davidsen@crdgw1.crd.ge.com (William E. Davidsen Jr) (08/14/90)

In article <1990Aug10.201729.15148@cunixf.cc.columbia.edu> cy5@cunixa.cc.columbia.edu (Conway Yee) writes:
| In article <2051@sud509.ed.ray.com> heiser@tdw201.ed.ray.com writes:
| >In the process of building a new machine, I think I did something REALLY
| >dumb.  I am putting a 386/25 board in a tower case, and basically 
| >followed the way the m/b in my AST 286 was set up.  That is, on the 
| >motherboard, where the screws go thru, there were metallic areas ... it
| >appears that AST has the motherboard grounded to the chassis.
| >
| >Well, I went along with this idea, and did the same on my 386 board in
| >the tower case.  When I powered the machine up, the power supply fan
| >wouldn't even start!  It appeared that maybe something was shorted out.
| >Anyway, I rummaged thru the ahrdware that came with the case, and found
| >some fiber washers.  I then re-installed the mb, using the washers to
| >insulate it from the chassis.  Now the system fires up, but the mb
| >seems brain-damaged.  

| Yes.  The darned thing is under warranty.  Let your vendor sort it out.
| Remember to swear on a stack of bibles that
| 	1) you did nothing wrong.
| 	2) you tried to replace everything else and it checks out OK.
| 	   Thus, it must be their fault.  They sent a fried board.
| Be sure to stand firm and insist on returning it.  Sometimes the sales
| people get to be real assholes when it comes to returns.


  You are a real piece of work. The original poster admits he shorted it
to ground, and you are telling him to defraud the dealer for it. And
obviously you are proud of this, since you posted rather than sent by
Email. You just tell the poster to swear on a stack of bibles that he
did nothing wrong when he admits he did.

  In my opinion your ethics are lower than whale droppings.
-- 
	- bill davidsen (davidsen@crdgw1.crd.ge.com)
	GE Corp. R&D Center; Box 8, KW-C206; Schenectady NY 12345

heiser@tdw201.ed.ray.com (08/14/90)

In article <10975@crdgw1.crd.ge.com> davidsen@crdos1.crd.ge.com (bill davidsen) writes:
>  You are a real piece of work. The original poster admits he shorted it
>to ground, and you are telling him to defraud the dealer for it. And
>obviously you are proud of this, since you posted rather than sent by
>Email. You just tell the poster to swear on a stack of bibles that he
>did nothing wrong when he admits he did.

Well, the whole thing has been solved.  As someone suggested, I checked 
the CMOS and XCMOS.  It had gotten zapped -- gee!  I wonder how?  :-)

Anyway, things are back to normal, and the system is running just fine!
(knock on wood!)


>  In my opinion your ethics are lower than whale droppings.

Do whale droppings sink or float?  heh heh heh ;-):-)



-- 
Bill Heiser
	Work:   heiser@tdw201.ed.ray.com
		{decuac,necntc,uunet}!rayssd!tdw201!heiser
	Home:   Bill.Heiser@f240.n322.z1.fidonet.org (Fidonet 1:322/240)
		The Think_Tank BBS (508)655-3848  1200/2400/9600-HST
	Other:  75106.2332@compuserve.com
	Other:	heiser@world.std.com     (Public Access Unix)