Is a DMM a good tool for fixing PCs?

[DPK]

I'm not even sure what a DMM is other then seeing somebody use one once. They basically are supposed to tell you what part of the PC is giving the trouble, right? How much do they run and are they worth having?

 

[amdskip]

Never heard of it, got a link anyone?

 

[notfred]

WTF is a DMM? I hate when poeple invent acronyms.

EDIT: based on my search at acronymfinder, I'm gonig to take a wild guess and say that out of the dozen lsited "DMM"s, you mean Digital MulitMeter.

In that case, no, it's not. It measures voltages and continuity and current and things, it doesn't say "this video card is bad". A multi meter can be sueful in diagnosing problems on simpler electronics... but only if you're an experienced electrical engineer and you have a schematic of the part you're working on.

 

[PrincessGuard]

A Digital MultiMeter measures voltage, current, resistance, capactiance, etc. It can tell you if something is electrically wrong with the computer but only if you know where to look.

 

[DPK]

Someone mentioned it in this thread, fifth from the bottom:
http://forums.anandtech.com/messageview.cfm?catid=38&threadid=1088514&FTVAR_MSGDBTABLE=

 

[tnitsuj]

I think he is referring to Digital Multi Meter. You really don't need one to work on PC's. most of the time you just replace what is broken rather than tracing down the fault.

I have only used my DMM (Fluke model something) on my car, and to fix an expensive integrated amplifier.

 

[hevnsnt]

I think he is referring to one of those ISA/PCI cards that you stick in and it tells ya what is wrong

 

[Demon-Xanth]

A DMM isn't too terrible useful when it comes to PCs. Given that I own a total of three, I do use them to check stuff, but not very often. A POST card can be quite helpful, some boards even have them onboard now. Notably Epox's two 7 segment displays (most useful) and MSI's 4 dual color LEDs.

 

[MegaloManiaK]

Originally posted by: notfred

In that case, no, it's not. It measures voltages and continuity and current and things, it doesn't say "this video card is bad". A multi meter can be sueful in diagnosing problems on simpler electronics... but only if you're an experienced electrical engineer and you have a schematic of the part you're working on.

I read that yesterday and wondered how you would use one in a PC. As far as i know you could use it on the PSU leads to make sure they are outputting the propper voltage and current, but from my knowledge you can't go in and measure any component that is acutaly part of a circuit, the only other place it would read accurately is at the input/output level, I.E. the PCI card pins, but how would anyone ever know what they are supposed to read.

I used my multi-meter when i built my desktop last month, but just to test continuity between the case and Mobo to try and figure out why it wasn't booting.

 

[MegaloManiaK]

Originally posted by: Demon-Xanth
A DMM isn't too terrible useful when it comes to PCs. Given that I own a total of three, I do use them to check stuff, but not very often. A POST card can be quite helpful, some boards even have them onboard now. Notably Epox's two 7 segment displays (most useful) and MSI's 4 dual color LEDs.

Linky? i would like to see one of those, it sounds useful. Btw im not making the obvious postcard joke here, so please dont link to one of the paper variety.

 

[Demon-Xanth]

random example

 

[Demon-Xanth]

There are also schematics available to make them. All it does is read a value put on the bus on port 80 during boot.

 

[MegaloManiaK]

Thats pretty neat. Not 250 dollars neat. But neat none the less.

 

[Demon-Xanth]

Like I said, there's schematics. Though the first one I found uses an EPROM to do the binary to 7 seg decoding where a 7446 or 7447 would do, and be easier.