"Gordon Elliott" <[EMAIL PROTECTED]> wrote: > > Tying the signal grounds together in an adapter is just fine, and should > cause no signal degradation. Other problems, like capacitance and impedance > change may be at fault, but grounds are not the problem.
Hi Gordon, Thanks for your input, but I don't think it's correct statement. My former occupation was electronic engineering, and I know for sure, how important the proper grounding is. Additional interconnection of ground lines at any point except receiver and transmitter, causes unwanted current fluctuations and signal modulation. > They are tied together in the monitor, and in the computer. Yes, but not directly. Each line is, so-to-speak, differential one, and separate ground returns are used for proper compensation of electrical noises. > The length of traces in most > adapters is relatively short with respect to the wavelength of signal > frequencies, The frequency 'per se' is indeed relatively low here, but please note that wave form is not simple sinusoid - it's a complex pulses with sharp forms and short times of change, so it causes various harmonical 'additions'. > but stray capacitance can be a problem and improper trace > widths and failure to use a ground plane can cause impedance changes that > make for reflections. Agreed. > If you make your own cable, it needs to have twisted pair wires of the exact > correct impedance. Existing monitor cables already have the correct > impedance, at least as well balanced as in the monitor use for a PC. (So if > it works on a PC, signal cable is already appropriate for the particular > monitor.) So either rewiring the existing cable or making an adapter would > probably make the best signal quality. This is exactly why I'm asking for the original cable pinout! :-) I've plenty of spare SVGA high-quality cables, so I believe it's quite simple to modify one of them by replacing the connector with Mac-styled one, if I'll find the monitor identification scheme for that model. > Be sure to connect ALL the grounds on each side. > (And yes tying them together at the computer side is OK, More precisely: "at the videocard's internal circuitry side", not elsewhere! :-) > But also if you have identification of Red ground > to Red ground that is fine also, Sure. > By the way, keep CASE > ground separate from SIGNAL ground, if that information is available--for > example the outer shield "D" shell is CASE ground and should only be tied to > CASE ground pins and shield, and a designated "drain" wire if used. Thanks, I know the difference between SG and PG! :-) Best wishes, Artur -- Quadlist is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Enter To Win A | -- Canon PowerShot Digital Cameras start at $299 | Free iBook! | Support Low End Mac <http://lowendmac.com/lists/support.html> Quadlist info: <http://lowendmac.com/lists/quadlist.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive: <http://www.mail-archive.com/quadlist%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
