Subby Posted June 5, 2012 Share Posted June 5, 2012 I've seen lots of discussion on video fixes for XL & XE (which are on my list to perform), but I don't remember seeing any for the original 800. Have I missed it? And if there is I'm thinking of doing it for one of my club meetings. Thx, Subby Quote Link to comment Share on other sites More sharing options...
venom4728a Posted June 5, 2012 Share Posted June 5, 2012 eBay Auction -- Item Number: 180898014176 These are available for the 800/400 Robert Quote Link to comment Share on other sites More sharing options...
SoundGammon Posted June 5, 2012 Share Posted June 5, 2012 The 800 already has a composite/s-video output! 5 pin din jack. Quote Link to comment Share on other sites More sharing options...
BillC Posted June 5, 2012 Share Posted June 5, 2012 The 800 already has a composite/s-video output! 5 pin din jack. So does the 130XE and there are video upgrades available for it, having both composite/s-video doesn't necessarily mean that the video output couldn't be improved on. I believe the 800 is regarded as having the best video of the Atari 8-bits and I haven't heard of any video upgrades for it, but that doesn't mean there aren't any. It has the same signal sources as the rest of the line and uses similar circuitry. Below is the 800 video circuit taken from the Jerzy SOBOLA schematic. Quote Link to comment Share on other sites More sharing options...
Subby Posted June 5, 2012 Author Share Posted June 5, 2012 800 has best stock video? Maybe I'm just unlucky then. I have two 800's and both have similar video, artifactting, a bit fuzzy, etc. (I did unplug the RF cable from the mobo) My 130XE is -way- better. And AFAIK, it has not been modified. Quote Link to comment Share on other sites More sharing options...
kenjennings Posted June 5, 2012 Share Posted June 5, 2012 Subby: There may be something broken then. I've had five 800s and out of the box they all had spectacular video out. A stock 800 is sharper than my 800XL and 1200XL with video mods applied. The 800 has only the slightest hint of vertical lines on the left side of the screen. Even the RF from the 800/400 is far better than the other Ataris (and other computers.) 1 Quote Link to comment Share on other sites More sharing options...
Subby Posted June 5, 2012 Author Share Posted June 5, 2012 If I get a chance tonight I'll swap the P/S board from one of my spares and see if that does anything for me. S Quote Link to comment Share on other sites More sharing options...
Faicuai Posted June 5, 2012 Share Posted June 5, 2012 The 800 already has a composite/s-video output! 5 pin din jack. This is correct. In a nut-shell, this what this machine's video output looks like: 1. NICE on composite, with low incidence of banding and/or luma+chroma combine-artifacts, passing pretty much all tests. 2. Y-signal Completely OVERDRIVEN in its (Y,C) "svideo" output: it WILL NOT pass a granular (16-shades) Gray-bar test, as the top-2 brightest bars will appear as a solid white patch (on the scope, the Y signal shows peak-voltage values as high as 4 VOLTS (!!!), on any given scan-line of those bright-white bars. The above results come from a basically PRISTINE 1983 late-edition machine (where most of HW revision were supposedly present). The reason for #2 above is the relatively UNTREATED Y-signal path coming out of its main amp/transistor, which only appears with a 75-ohm resistor). For this reason, the 800 NEEDS to be (minimally) modified for sVideo output, and basically NO modification for composite output. Quote Link to comment Share on other sites More sharing options...
+bob1200xl Posted June 5, 2012 Share Posted June 5, 2012 I think you will find both the 130XE and 800 have optimal video if you terminate the cable (best at the monitor end) with 75 ohm resistors. Bob Quote Link to comment Share on other sites More sharing options...
Subby Posted June 5, 2012 Author Share Posted June 5, 2012 I forgot to mention that I am using a composite monitor, the Amdek Color-I. Quote Link to comment Share on other sites More sharing options...
flashjazzcat Posted September 18, 2012 Share Posted September 18, 2012 Finally got around to looking into the 800's video quality. The only problem seemed to be the overdriven luma, so I replaced R189 (75 Ohm) with a 220 Ohm resistor, and that was it. Here's the output on my LG M227WD LCD: 4 Quote Link to comment Share on other sites More sharing options...
Faicuai Posted September 19, 2012 Share Posted September 19, 2012 Finally got around to looking into the 800's video quality. The only problem seemed to be the overdriven luma, so I replaced R189 (75 Ohm) with a 220 Ohm resistor, and that was it. Here's the output on my LG M227WD LCD: NICE first step. Glad you fixed over-driven Luma signal. However, you stil have color-banding which is the product of limited control of Y/C separation or pre-combination, during generation of Composite signal. Exactly the same problem as seen on my 800XLs. Once my long-awaited Incognito arrives, I will work on improving the quality of Y+C signal from my JM-800, as simply and effectively as possible, and (if positive results), I will come back and post some decent pics./actual-captures, so everyone can replicate the results. Quote Link to comment Share on other sites More sharing options...
flashjazzcat Posted September 19, 2012 Share Posted September 19, 2012 NICE first step. Glad you fixed over-driven Luma signal. However, you stil have color-banding which is the product of limited control of Y/C separation or pre-combination, during generation of Composite signal. Exactly the same problem as seen on my 800XLs. Once my long-awaited Incognito arrives, I will work on improving the quality of Y+C signal from my JM-800, as simply and effectively as possible, and (if positive results), I will come back and post some decent pics./actual-captures, so everyone can replicate the results. Good luck - I'll be interested to see the results. However - I'm done. I tried removing a couple of resistors and completely isolating the Y/C signals (thus disabling the composite signal), but it looked no different on this display - and out of a dozen display devices (CRTs, LCDs), this 1080p LG is head and shoulders above the rest in terms of s-video. However, that also means that any tiny imperfections are faithfully rendered, too. But if a machine looks good on this monitor and not others, I blame the other monitors. The display quality may still not be perfect, but I don't have macro eyes, so I'm happy to leave it there. Quote Link to comment Share on other sites More sharing options...
Tempest Posted March 6, 2013 Share Posted March 6, 2013 Once my long-awaited Incognito arrives, I will work on improving the quality of Y+C signal from my JM-800, as simply and effectively as possible, and (if positive results), I will come back and post some decent pics./actual-captures, so everyone can replicate the results. Have you had any luck fixing the video quality? I'm having the same issues and I'm looking for a good video mod. Quote Link to comment Share on other sites More sharing options...
Magic Knight Posted March 6, 2013 Share Posted March 6, 2013 Just saw this topic.. I agree the 800 has excellent default outputs - i use the S-video and its almost as good as a direct feed from the I.C.s on the main PCB. pity most of the others (400 XL series and some XE) are not that good - especially the poor composite after the post circuitry involved. Quote Link to comment Share on other sites More sharing options...
adam242 Posted March 9, 2013 Share Posted March 9, 2013 Finally got around to looking into the 800's video quality. The only problem seemed to be the overdriven luma, so I replaced R189 (75 Ohm) with a 220 Ohm resistor, and that was it. Here's the output on my LG M227WD LCD: WOW. This simply works. Just did this same resistor swap on my own 800, and I'm blown away at the sharpness and clarity. Thank you! Quote Link to comment Share on other sites More sharing options...
chad5200 Posted April 21, 2019 Share Posted April 21, 2019 WOW. This simply works. Just did this same resistor swap on my own 800, and I'm blown away at the sharpness and clarity. Thank you! I just did this to my 800. Major improvement! Looks great! Thank you FJC!!! Quote Link to comment Share on other sites More sharing options...
DavidMil Posted April 21, 2019 Share Posted April 21, 2019 Well I have to admit that this mades a very big difference in the intensity of the colors! Such a simple modification and yet it makes a big difference. Now I'll pull apart my other 800's and do this same mod. Thank you flashjazzcat, David Quote Link to comment Share on other sites More sharing options...
DavidMil Posted April 22, 2019 Share Posted April 22, 2019 I did the same mod in another of my 800's and the colors are definitely better on it too! It's just a lot of trouble to strip an 800 down to the MB. I don't think I'm going to go through all that trouble for my 800 that I use for programing. David Quote Link to comment Share on other sites More sharing options...
spinnaker15136 Posted April 28, 2019 Share Posted April 28, 2019 So where is R189 on the board? Is it it a place where I can just clip off the old resistor and not have to lift the board? Quote Link to comment Share on other sites More sharing options...
chad5200 Posted April 28, 2019 Share Posted April 28, 2019 You have to completely disassemble everything to get to R189. But it’s worth it. Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
spinnaker15136 Posted April 28, 2019 Share Posted April 28, 2019 (edited) You have to completely disassemble everything to get to R189. But it’s worth it. Sent from my iPhone using Tapatalk So where is it. located? That is what I want to know. And can you clip out the old one without lifting the board? I.E. solder the new one to the old leads. Edited April 28, 2019 by spinnaker15136 Quote Link to comment Share on other sites More sharing options...
+DrVenkman Posted April 28, 2019 Share Posted April 28, 2019 And can you clip out the old one without lifting the board? I.E. solder the new one to the old leads. Ugh, don’t do that. If you’re going to replace a resistor, do it right: remove the old one, clean out the through holes with a solder sucker or wick, then solder the new one in place. 3 Quote Link to comment Share on other sites More sharing options...
spinnaker15136 Posted April 28, 2019 Share Posted April 28, 2019 Ugh, don’t do that. If you’re going to replace a resistor, do it right: remove the old one, clean out the through holes with a solder sucker or wick, then solder the new one in place. Well that is what I would do for anything I designed and built. Or even something I was repairing that was not working. But what I have is a working system and wanted the least invasive way to swap it out. Quote Link to comment Share on other sites More sharing options...
DavidMil Posted April 28, 2019 Share Posted April 28, 2019 There is no way to get to it without removing the big aluminum casting. I suppose you could snip out the resistor and solder the replacement to the existing leads. It's about two inches in front of the right side cartridge socket. Right beside a ferrite bead. David 1 Quote Link to comment Share on other sites More sharing options...
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