Theoryman Posted January 19, 2019 Share Posted January 19, 2019 (edited) Dug out my XEGS as my wife likes its appearance and is ok with it sitting in the living room. When I put it up about 15 years ago, it worked fine... Now... Black screen. Power supply is steady on 5.03VDC and works on my 800XL. Green light comes on when you push the power button. Black screen in 720x240x60P is reported by my TV... With it turned off the TV reports no connection. Same as my 800XL. No chips get hot after 15 min run time. Memory is NOT the MT chips. Star Raider does not start... All tests have been done with the keyboard disconnected. Board is not corroded. All chips are soldered... No sockets. I have a DVM, 5MHz analog oscilloscope and a rework station. I also have an EPROM/EEPROM burner on a Windows system I really need a schematic and some suggestions where to start... -- Edited January 19, 2019 by Theoryman Quote Link to comment Share on other sites More sharing options...
Rybags Posted January 19, 2019 Share Posted January 19, 2019 Initial powerup video and sound can provide an enormous clue but you seem to be using a modern TV which might have lag locking onto the signal which can mean you might miss some of it. Normal sequence on an XL or XE - static then power on should produce a screen that might roll then lock on correctly. GTIA registers will usually have some randomness which means for a fraction of a second there's usually a redish brown dark screen and sometimes vertical stipes (Player-Missile data). If the OS starts OK there should be a click around the same time the whole screen turns black. The screen should remain black for the entire period that the system verifies contiguously found RAM and the amount found will determine the delay. On XL that can be 16, 40 or 48K, XE same except not 16. Once the preliminary RAM test passes you should get normal startup/boot behaviour, ie test for presence of disk with E: device started with blank blue text screen. In the case of some carts, Star Raiders is a diag mode cart so gets control straight away so the startup behaviour is slightly different. Expect same behaviour until click/black screen then the game should immediately display without the RAM test delay. Since you have a 'scope. You could try stuff like Sync pin on the 6502 to see if it executes instructions. Since you have a working machine you can test same on it and compare. Other possible problems can be OS Rom, MMU, Ram chips, Freddie. Quote Link to comment Share on other sites More sharing options...
+Nezgar Posted January 19, 2019 Share Posted January 19, 2019 Since you mention you have a programmer, this may be an easy one to test: If the OS ROM is bad, it is pin compatible with a 27C256 EPROM (or 28C256 EEPROM). If you desolder it from the PCB (and replace with a 28 pin socket), you should be able to read it as a 27C256 on your programmer, and compare it with a known good image. (Which I'll try to find for you) Edit: XEGS ROM here: http://atariage.com/forums/topic/259483-xegs-game-rom/?p=3639787 Quote Link to comment Share on other sites More sharing options...
1050 Posted January 19, 2019 Share Posted January 19, 2019 Schematic will be found inside jsobola.zip in this post http://atariage.com/forums/topic/235441-whats-up-with-jerzy-sobolas-site/?do=findComment&comment=3187242 It's called xesys.zip Jerzy has this one a bit fouled up with the 130XE and of course there is always Jerzy's habit of wrong number or pin you might wander across too. Only XEGS schematic I know of though. These have an unusually high accounting of bad OS ROM for some reason. Best to just get 27C256 of 200ns speed and burn a new one right now since you can. Rom file here: http://atariage.com/forums/topic/259483-xegs-game-rom/?do=findComment&comment=3639787 That Nezgar fella is pretty quick with the whip... 1 Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted January 19, 2019 Share Posted January 19, 2019 (edited) you should see 480 as the resolution on your monitor unless using an upscaler... some televisions don't do 480i or p and some don't do 1080p... avoid such tv's if you don't see 480 as a choice you have to use a converter... I only have come up against this twice in so many years.... Edited January 19, 2019 by _The Doctor__ Quote Link to comment Share on other sites More sharing options...
+Nezgar Posted January 20, 2019 Share Posted January 20, 2019 you should see 480 as the resolution on your monitor unless using an upscaler... some televisions don't do 480i or p and some don't do 1080p... avoid such tv's if you don't see 480 as a choice you have to use a converter... I only have come up against this twice in so many years.... Well.. 480 lines is correct for an interlaced NTSC signal, but the Atari output is non interlaced, so 240 lines would technically be correct... Should still confirm if that particular TV is not handling the video signal correctly... Quote Link to comment Share on other sites More sharing options...
Rybags Posted January 20, 2019 Share Posted January 20, 2019 I don't think any modern TVs report 240p. Many TVs just asssume an interlaced signal and will in fact generate 480i from the Atari output. Some can't handle the signal properly at all but it's pretty rare. I remember trying an ST on the first HDD recorder I had (still got it, it fried it's PS) and got nothing but a white rolling screen. 1 Quote Link to comment Share on other sites More sharing options...
Theoryman Posted March 4, 2019 Author Share Posted March 4, 2019 Thanks for all the advice! Sorry it took me so long to get back... My big PC workstation died the next day after I posted that and I've had to build a new x86 system... Since my old one was bleeding edge when I built it in 2006 and I was able to keep upgrading it until 2019, I decided to build a new bleeding edge system and it has taken a bit of time to get it done... Rybages -- Thanks for that detail... I'm going to go dig out my 1701 monitor to test that. Nezgar -- Since I plan to upgrade this system anyway, socketing the OS and testing it makes sense. 1050 -- Thanks for the links to schematics... pulling them all down... About my TV and its reports of scan rates... Yes, that is correct. I bought this TV about 5 years ago because it would do LOTS of different resolutions. Via the component inputs, I have had it display all the modes below: 320x 200Px70 MCGA 256color 720x 240Px60 NTSC non-interlaced 720x 288Px50 PAL/SECAM non-interlaced 640x 480Px60 VGA 720x 480Ix60 NTSC interlaced 720x 480Px60 NTSC Progressive (DVD) 720x 576Ix50 PAL/SECAM Interlaced 720x 576Px50 PAL/SECAM Progressive1280x 720Px60 Middle level HD 16x91024x 768Px60 XGA1280x 800Px60 WXGA1366x 768Px60 XVGA1440x 900Px60 WSXGA1680x1050Px60 WSXGA+1920x1080Ix60 HD Interlaced 16x91920x1080Px60 HD Progressive 16x9 I use a CP-VSRGB (EA0057) off Amazon https://www.amazon.com/gp/product/B01EK7YJJG/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1 to convert composite or S-Video to YPbPr for component input. It does no scan rate conversions... Just decodes most ANY analog color format down to RGB or YPbPr. I've done weird video trans-coding for a long time... I also have 19" 4x3 tube unit that can display almost any NTSC / PAL / or SECAM video that I've thrown at it... As well as MCGA, CGA and EGA through the SCART. Thanks again and I'll be back as I discover more about this broken XEGS. -- Quote Link to comment Share on other sites More sharing options...
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