[ISMAP]-Deja News Toolbar Interest Finder Browse Groups New On Our Site! Search ______________________________ Find Find messages in the [complete] archive uBid Online Auction uBid Online Auction Message 80 of 214 return to comp.sys.cbm [USEMAP] previous · post reply · next help Re: C128 Tower Question more options Author: Nate / DAC Email: natedac@southwind.net Date: 1999/01/14 Forums: comp.sys.cbm more headers author profile view thread _________________________________________________________________ Message segment 1 of 3 - Get Next Segment - Get All 3 Segments > [Your system consists of:] > > 128D motherboard, HD-500, RamLink, SCPU128, EX-3, T232, 1750XL, SID > Symphony, FD2000, 1541, 1571, SCSI CD-ROM, USR 56K modem, MW-350 printer > interface, GeoCable. > 1). What must be done to fix that awful sounding SID on the 128DCR? Replace the 8580 SID chip with a 6581. Place a jumper across CR17 (located right behind the SID chip). Replace C82 and C83 with a pair of 470 pF polystyrene capacitors. You are also supposed to replace C96 and C97 with a pairof 1800 pF capacitors as well. Also, you're supposed to add a 1K resistor in theslot marked for R11. I didn't bother with C96, C97, or R11 - the differences seemed minimal. My mouse works just fine also. > 2). Will the face pannel from a 1541C drive with Newtronics mechanism fit > the Newtronics mech from a 1571? I'm not thrilled with the thought of > fabricating something to fill in. It should, but I dunno for a fact. For the 1571 I put into my C128 Tower, I made a faceplate out of one of the 5 1/4" drive bay "knockout" panels. > 3). Is the circuit board from the 1541C smaller than the older one(s)? If > so, will it function with the Alps mechanism? If so, is it 100% > compatible with fastloaders and copy protection? I'd like to keep the > 1541 an Alps mech to distinguish it from the 1571. Besides, that old > mech sitting in a tower looks so unique.... You would be far better off using the board from a 1541-II, since it is the smallest stock 1541 drive board C= made. > 4). How far can one extend the keyboard (assuming good shielding) without > encountering trouble? I have a 6-foot parallel "printer extension" cable which I extended my keyboard with. You may have to remove some capacitors from the C128-DCR motherboard with this arrangement, since you have a Super CPU - the extra capacitance from the cable causes problems at very high program speeds. Those capacitors, in my case, were C200 through C218, C43 through C54, and C99. They are all used as "interference" eliminators (I guess for FCC compliance), and aren't vital toproper opration. Simply wiggling them with your finger one at a time, until they break off at the base, will do fine to remove them. > 5). Where does one connect switches to the DCR motherboard to change > device number or disable it? Underneath the drive mechanism there are two unmarked jumpers. They lead to a large ground trace on one side, and to two thin traces on the other side, which lead to pin 15 and 16 of the 6522 right next to the jumpers. Cut the jumper nearest the front edge of the board (it isn't very close to begin with btw), and place a SPST switch across the pads. Alternatively, you may place the switch between any nearby ground trace, an pin 15 of the 6522. This first jumper switches between device 8 and 9. Cut the other jumper and place a switch across it as well (or between ground and pin 16 of the 6522), to expand your range to 8-11, just as with any stock 1541 drive. > 6). Will one of those automatic printer switches I see for sale everywhere > function to switch between the interface and the GeoCable? I don't see why not, all the interface should need is to see the printer interface's "/STROBE" output line golow, which tells the printer that data isvalid on the port. > 7). What other gremlins am I likely to encounter in doing this? * You will eventually have to wire up an expansion port cable. For crying out loud, use high quality wire, and if possible, shielded. I am still having minor problems with my setup, which I can only attribute to a lossy/noisy expansion port extender cable I constructed.. That cable was made with shoddy parts and cheap wire :-/ * You will also want to wire up a User-Port extension cable. This cable on the other hand, will be fine with any cheap ribbon cable, since that port isn't nearly as noisy as the expansion port. Message segment 1 of 3 - Get Next Segment - Get All 3 Segments _________________________________________________________________ Email a Friend [USEMAP] previous · post reply · next help uBid Online Auction uBid Online Auction Home · Search · My Deja News · Post · Power Search · Help · How are we doing? 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