I ran out of your cables so having these made off the design on the page you made
On Wed, Sep 25, 2024, 6:25 PM Brian K. White <[email protected]> wrote: > Let's see the rest of that dvi cable. > > If you bought a cable from arcadeshopper, you should not need to do that > even-to-odd crossing. > > You would need to twist the wires only if the rest of the cable was all > standard IDC connectors. > > The cables I made for arcadeshopper all include a part that does the > twist. (Unless maybe he's sold all of those and now selling something > else.) But the best version of cable comes in 3 pieces and one of the > pieces is a male-to-male plug that has the twist inside, so that all the > rest of the cables can be standard, so you could replace the cable if it > wears out, or add an extension for more length, etc, without needing to > do anything funny. > > Another confusing element is, the tandy manuals number the pins > incorrectly on the 102/200 end. What they call pin 1 in the tandy manual > is actually pin 2 of the connector. So what the 200 service manual calls > pin 1 does not go to the triangle mark on the connector. But the DVI > manual does number the pins correctly. > > The end result though is, Take the entire cable including all parts and > adapters that you might be using (those individual wires in this pic are > new to me, is it something you made up yourself?), and pin 1 at the DVI > end needs to go to pin 2 at the 200 end, and when I say pin 2 I mean the > real pin 2 according to the standard way to number the pins on that > connector, not what the 200 service manual call pin 2. > > Here are several ways to make a cable > http://tandy.wiki/Disk/Video_Interface:_Cable > > The simplest for a 200 is to get a male-male gender changer pin header > like at the bottom of the page, or better yet, take 2 male boxed headers > and solder them back to back with the polarity notches on opposite > sides. This produces the same result as twisting the wires, even though > physically it's just passing straight through, but 1 goes to 2, 3 goes > to 4, etc. > > Then just use an ordinary 40 pin cable with female connectors on both > ends, installed normally, no funny business, like a standard IDE or gpio > cable or something (as long as it has all 40 pins, many ide cables have > one pin missing and/or one wire cut). > > If you follow the github links to build a cable yourself, there are bom > links there to the actual parts on digikey. > > If you have an arcadeshopper 3-piece cable, just plug the long cable > into the dvi, then plug the male-male adapter on the free end, then plug > that into the 200. Don't use the 3rd piece with the DIP-40. > No twisted wires like in this pic. The male-male adapter does that already. > > -- > bkw > > > On 9/25/24 19:46, Tom Blum wrote: > > Hello, > > > > I'm looking for any thoughts about potential faults that could explain > > the following. > > > > * T200 (that has been thoroughly inspected inside/output) powers-up and > > is functional when not connected to DVI. Also powers-up and functions > > with system interface cable attached to T200 as long as cable is not > > connected to DVI. No optional ROMS are installed. Available memory at > > power-up is 19K+ > > > > * Disk/Video Interface operates to spec when not connected to T200. DVI > > boot sequence is nominal. Successfully loads ver 1.00.00.200 of disk > > basic and displays confirmation of such on composite monitor. > > Successfully boots with system interface cable attached to DVI and T200 > > _as long as T200 is not powered on._ > > > > * When T200 is connected via system bus to DVI (_with DVI powered off_), > > T200 does not successfully power on. When the T200 power button is > > pressed, the LCD screen goes solidly dark with no apparent other > > functionality. It seems frozen. When DVI is subsequently powered on, > > while T200 remains in frozen state, DVI sometimes succeeds and sometimes > > fails to load software from the DVI disk. T200 can only be recovered by > > cycling memory power switch on the underside of the T200 off-on. > > > > A picture of the connector is shown below. It has been connected to the > > T200 and DVI per illustrations from Arcade Shopper. As a cross-check, > > I've ensured that pins on the connectors are intact and fully-inserted. > > Intuition suggests that the issue resides with the T200 system bus, the > > T200<->DVI cable and/or the "PPI" circuit of the DVI. Ironically, the > > service manual for the DVI refers users to the T200 service manual if > > there are issues with loading disk basic onto the T200. The T200 > > service manual/troubleshooting section does not address this problem. > > > > Any thoughts on where to start? I do have a spare, working T200 > > motherboard. Swapping that in might help rule out issues on the T200 > side. > > > > Thanks, Tom > > > > > > > > > > > > -- > bkw > >
