From: epass@nyx10.cs.du.edu (Eric Pass) Newsgroups: comp.sys.cbm Subject: SX-64 User port Text file Date: 5 Nov 1995 14:59:10 -0700 Hi all, Here's some info on the SX-64 User Port which may be of interest to SX-64 owners (and others). TEXT IMPORT BEGIN ================= SX-64 vs Vicmodem & Promenade ----------------------------- By E.T. Bear Second Source, a Commodore service center located here in the Sacramento area, recently had an SX-64 in for repair, they found that the regulator in the power supply was bad, they replaced it, the owner picked the unit up, a few days later it came back, again they found the same regulator bad, replaced it a second time, once again the owner picked it up and again brought it back, with the same problem. They asked the owner what he was doing when the SX went down, he was telecommunicating, using the famous Commodore "Vicmodem". Second Source then called CBM and asked them about the "Vicmodem and the SX". Commodore stated that the two are not compatible. Why they have or did not pass this information along, only CBM knows. Isn't this always the case with CBM? If you own an SX and a Vicmodem, it would be best not to use them together. Jason-Ranheim Co., now located in Auburn, Ca., has a publication that warns the owners of the SX-64 not to use their Promenade C1 on the SX, as you may damage the SX. In the publication they state the problem and the solution. The problem: ------------ Commodore made a change in the USER PORT on the SX as compared with the C-64. On the SX, Commodore grounded one leg of the 9v AC supply. The Promenade uses this supply and it requires that the 9v AC be "floating" from ground as it is in the C-64. The Solution: ------------- Jason-Ranheim has outlined a solution in their publication. You will require the following tools: 1- #1 phillips-head screwdriver 2- A sharp knife First: You will have to locate and remove the four (4) screws that hold the plastic side moldings, then remove the two (2) corner mounting screws located at the upper rear corners of your SX. Next: Remove the cover of the SX by locating and removing the three (3) flathead screws at the upper portion of each side of the computer. The cover should now be free. Next: Now locate the small printed circuit board at the top rear of the SX which carries the USER PORT, Serial Port, and Joystick Ports. Remove the three (3) round head screws holding the board to the frame. Next: Raise the board up and forward to expose its underside. Next: Locate the foil strap connecting pins 11 and 12 of the USER PORT. Cut this strap with with the sharp knife. With a voltmeter check that the 9v AC is now isolated from ground. If it is then reassemble the SX reversing the disassembly procedure. On the Promenade there are two (2) nylon assembly screws that may interfere with the heat sink on the SX. You can either cut the heads off with a sharp knife, or you can disassemble the Promenade (voiding the warranty), and replace the screws with #6-32 x 1/2 flathead screws after having counter sunk the holes in the base. This would be the preferred method. Here is the new address for Jason-Ranheim: Jason-Ranheim 1805 Industrial Drive Auburn, Ca. 95603 Call: (916) 823-3284 Technical Support (916) 823-3285 Remember any modifications that you make to your equipment is your responsibility and may void warranties. TEXT IMPORT END =============== -- Eric W. Pass (epass@nyx10.cs.du.edu) | "I have a cunning plan which cannot http://nyx10.cs.du.edu:8001/~epass/home.html | fail, my lord." - Baldrick --------------------------------------------------------------------------- All sorts of game stuff for sale on my Web page, follow the URL above!! From: bjheyboer@space.honeywell.com (Brian Heyboer) Newsgroups: comp.sys.cbm Subject: Re: SX-64 User port Text file Date: 6 Nov 1995 21:54:40 GMT In article <47jc3e$qbq@nyx10.cs.du.edu> epass@nyx10.cs.du.edu (Eric Pass) writes: >Here's some info on the SX-64 User Port which may be of interest >to SX-64 owners (and others). >The problem: >------------ > >Commodore made a change in the USER PORT on the SX as compared with the >C-64. On the SX, Commodore grounded one leg of the 9v AC supply. The >Promenade uses this supply and it requires that the 9v AC be "floating" >from ground as it is in the C-64. Another device that will fry your unmodified SX-64 is an MSD RS-232 interface. Other devices, however, will not work on a MODIFIED unit -- the Datel EPROMMer is an example. There is also a fix for the serial port to make it compatible with some fast loaders. This was also known as the "Q-Link fix" because Q-Link's built-in (not quite so) fast load routines were one of the best known examples of problems with this. The fix here is a 3.3K ohm pull-up resistor in the /SRQ line.