From: news-1171796400@discworld.dascon.de   
      
   In article ,   
   Mitchell Spector   wrote:   
   >>Are the vertical lines on colour or mono monitor?   
   >>If colour, it might be a power supply problem.   
   >   
   >    It's on the color monitor. The lines are very subtle though, not   
   >something immediately noticable unless you look closely. I've seen   
   >the same effect on old VGA cards and a genlock video card on   
   >my Apple II.   
      
   In that case, it might be tolarances - however, bad capacitors in the power   
   supply or on the mainboard, or bad cabling might also be the cause.   
      
   >    Speaking of monochrome screens, I passed up a 12" Atari   
   >monochrome screen with this system (may be too late to get it   
   >now, the owner said he was throwing it out if I didn't take it).   
   >Is it possible to hook up the ST to a VGA screen to display its   
   >640x400 mode? I even have some that sync down to 15 kHz,   
   >but then I suppose finding a DIN 13-pin to VGA adapter is not   
   >going to be easy.   
      
   It works, but you will probably have to build that adapter yourself - wire   
   mono out to all three (RGB) video inputs on the VGA monitor, connect HSYNC   
   and VSYNC, and ground the mono detect pin on the atari side.   
      
   Most VGA monitors will sync to the ST's frequencies, although on some you   
   can't get the image to fill the screen completely.   
      
   >motherboard part number: "C070789-001 Revision D/Action D2".   
   >I vaguely remember the DRAM chips were underneath the power-   
   >supply (rather than the front end) and it's likely it may only have 2   
   >sockets for ROMs rather than 6. How would you go about getting   
   >it to use 6 chips if there's only 2 sockets? A plug-in daughterboard?   
   >Or just a different set of ROMs?   
      
   If there are provisions for 6 ROMS, but only 2 sockets, you could retrofit   
   the missing sockets. On later machines, there were really only 2 sockets   
   supported - in that case, you need a set of 2 (bigger) ROMs, or EPROMs.   
   27C010 EPROMs have 32 pins instead of the ROM's 28 pins, so you need a tiny   
   bit of wiring (or an adapter socket) to match the pinouts.   
      
   >    My main concern with the 1040-STfm is it's RF modulator has   
   >sound but no picture--I just get a black screen. I'd like to repair it   
   >so I can get composite output working. Any tips on how to go   
   >about repairing that?   
      
   I never used modulators - FBAS input to a TV gives much better quality.   
      
   An oscilloscope and schematics will be helpful, but I am not sure if   
   schematics of the modulator box itself were available - I can not currently   
   find my collection of printed ST schematics. If RGB output works, there is   
   not much outside the modulator box that could cause the problem.   
      
   cu   
   Michael   
   --   
   Some people have no respect of age unless it is bottled.   
      
   --- SoupGate-Win32 v1.05   
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