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. They are tied together in the monitor, and in the computer. The length of traces in most adapters is relatively short with respect to the wavelength of signal frequencies, 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.
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. If someone has a schematic (pointer thereto) one could make an inexpensive adapter by wiring across. Be sure to connect ALL the grounds on each side. (And yes tying them together at the computer side is OK, especially if the number of grounds differ. But also if you have identification of Red ground to Red ground that is fine also, etc., for the color video signals, in that case try to twist with video signal even for short distance of wiring adaptor which should be kept to say 1" or less.) 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. Can somebody help with schematics of adapters and cable wiring? (Has this already been presented?) -- Gordon Elliott ----- Original Message ----- From: "Artur Yelchishchev" <[EMAIL PROTECTED]> To: "Quadlist" <[EMAIL PROTECTED]> Sent: Monday, September 22, 2003 5:30 AM Subject: Apple Multiple Scan 1705 Display > Gentlemen, .... > IMHO, this problem is caused by adapter design: I've found that all the > "signal ground" lines are soldered together (!), so I'm thinking about > building my own cable. The problem is, that I'm unable to find exact > pinout for that monitor. The service manual > (multiple_scan_1705_display.pdf) seems to be removed from everywhere, > but maybe someone can provide me with full wiring schematic of Mac > cable? ... -- 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
