TroyQ

Off topic: Not sure if I would phrase it quite like that. Back on topic: Agreed, there is a finite number of these chips and some day supplies will dwindle.

Thanks for pointing me in the right direction! Yep, looks like it was the cable. I shortened the KB side to just a few inches and most of the problem is gone. Any suggestions on a good 5 din cable with an SVID connector? I haven't found any RCA -> SVID adapters that are wired correctly to work with the "standard" Atari 4-RCA cable.

Here you go. The one with white wires was as I was testing and I had just cut the original chroma wire (pre uav). The one with the blue wire is how it is now - completely removed the original chroma mod.

Yep, that's the cap I lifted before I did the UAV upgrade when I was just wiring up the Chroma line to the 5 pin din. After the UAV upgrade, I've experimented with putting C56 back in circuit and lifting it and it had no effect on the bars,,,

I've got an 800XL that produces vertical bars that I've been trying to get rid of. Currently, I'm using SVideo (Chroma/Luma) -> VGA Converter -> LCD Monitor. Initially I added the missing chroma line and lifted a single cap so that chroma was output on the 5-pin din. I've removed the RF modulator Installed a UAV rev D I thought it might be some kind of cross talk/interference in the cable itself - the cable is one I hacked together using an AT KB Extension + SVideo cable. To eliminate the cable as the issue, I wired in a second 5 pin din (the female side of the AT KB extension) directly to the UAV and the result was no bars - clean solid blue background. I've checked the cable for continuity or even some level of resistance between between the pins on the cable and didn't get anything so I don't think its the cable. The problem only happens when I try to use the built in 5pin din port. If I go directly from the UAV, everything is fine but when wiring the UAV output back into the motherboard, the problem reappears. I've narrowed it down to be something with the composite line. If I don't connect that line from the UAV to the motherboard (UAV Pin 2 -> L7), then everything looks fine. (The attached pic shows the ground wire hanging - that was part of testing; connected vs not connected didn't change anything). Is there some kind of back-feed happening from the composite line onto the Chroma/Luma lines on the motherboard? Is that possible? I've removed the original Chroma wire (used pre UAV) - no effect. I put the 1 lifted cap back into the circuit - also no effect; i've since lifted it again. Any ideas? Any other components that can be removed that will separate the composite line from the C/L lines on the motherboard?

Its been a bit since I've been able to do any troubleshooting on this but I've finally had the time and I've found a solution: Bad ANTIC chip. Things it was not: Bad RAM ** (replacing the RAM did not fix the failure, but afterwards, the logic probe produced accurate results on the FREDDIE chip - so it is possible there were also bad RAM) Bad CPU Bad GTIA Bad 10uF or 22uF caps I think I got lucky with my 130XE board in that it was not too much trouble desoldering / adding sockets. By my count, I did 452 pins total and no lifted traces or anything bad. I now have a mostly socketed motherboard. I may still socket the rest of the chips and replace the 4.7uF & 470 uF caps just to satisfy my own OCD-ness. I saw there is another thread for tracking good/bad Mt RAM. I'll put the original ram back in and post the results and pix there. Again, thanks to everyone and their advice on this.

Small update: Super big thanks for this link! I didn't see it at first, but I found the logic table for all the ICs in that PDF. I have been busy, so only had a chance to do an initial sanity check of "am I using the logic probe correctly and getting accurate results" Looks like I am. I tested FREDDIE against the Logic Chart in the PDF and had 3 discrepancies: pin 21 should pulse and I get low, pins 34 & 38 should pulse and I get high. Pin 21 is A12, pin38 is R/W and pin 34 goes to pins 3 on DRAM (if I understand the schematic correctly). I know I need to do some more testing, but that to me looks like the issue is memory subsystem related. An address line (A12) is stuck low and the R/W is stuck high (trying to write?). RAM or FREDDIE I am guessing?

Is there any documentation or flow charts that document the actual boot process? I'm assuming it is something much simpler than a PC POST, BIOS Init and Boot. Something along the lines of power on, all chips get power and perform some kind of init, CPU begins execution at a specific memory address (in the OS ROM chip)? Is the OS ROM copied to RAM first or is it just mapped within the 64K space and then execution begins at a specific memory address? For the RAM, if I probe the CAS/RAS lines, I assume I should see constant activity there? Freddie would be generating that? Would Freddie do that regardless of what is happening with the rest of the system (ANTIC, POKEY, etc)? Or to put it another way, if there is no CAS/RAS activity, does that point to Freddie or could that happen due to some other failure (OS ROM for example)? Is the OS ROM a common failure? Its just a ROM chip, right? I always thought ROM/PROM/EEPROM etc were fairly tank-like and mostly indestructible. The amount of abuse a cart can take is pretty substantial (cough cough digging up functional 2600 ET carts from a landfill after 30+ years). Assuming that there was not some wild voltage surge, what would cause the OS ROM to die? Thanks for the link. There are a few steps in there that I will check, but it is pretty sparse with regards to a no boot failure. Reading it, it looks like if the CPU passes some basic RESET failure checks, the next steps are to start swapping chips until it works. And I could see that that would have made sense for a service center that probably had a stock of known good test chips; that's essentially the process for any PC/Server related repair: replace boards/drives/ram/cpu until the problem is gone. LOL. Yes, I will definitely post pix of the RAM. I used to be a Network Engineer for a company called CompuCom. Probably never heard of them, they've been bought up by someone else since I left. At the time, I supported HP, Compaq, Dell & IBM servers & workstations - IMAC, setup, admin & repair. But that was long ago, now I am a software developer for a vegetable seed company. Thanks! I had a feeling that was the answer. I was hoping that someone would have some magic "Probe @ X & Y and result W means chip A is ok/bad" etc but I see that was probably too much wishful thinking, oh well. I am still waiting for RAM and in the mean time I will start poking around with the probe and see what I find. I will try to do some A/B comparisons with probing a good 800XL and see if there are any obvious differences and post any useful results. Thanks again for everyone's advice!

LOL - no, I have not been chased away; the holidays (US) have taken up most of my time. The strong opinions and views don't bother me a bit; I've been in IT way too long for that to bother me. I'm still waiting for RAM to arrive, so there hasn't been too much to report. I did swap the banks (R111 & R112 swapped). Still had the same result - so it didn't really help. It all went smooth, no lifted trace, so I am hopeful that it portends good things for the future. @1050 - thanks for the link for the pico scope. If I was going to be doing a lot more chip level work, I would seriously think about it; but with a whole board replacement of $80, I have to weigh the cost to figure it out vs the cost to just make it work. Of course, there is still the voice in my head that says "Go Ahead... its a tool. You know you need it!" I've taken pix of the RAM, so if they end up being the issue, I can post for any date code,etc documentation. @DrVenkman - $20 is more in my budget , so I did get that logic probe. Now, with logic probe in hand, suggestions on where to start checking?

Thanks everyone for your advice and input! Even with differing opinions, its good to get different points of view - it is all appreciated! Even though I've spent most of my life maintaining servers & workstations, I guess I've gotten a little spoiled by just replacing defective boards and not worrying about which component on the boards had failed. @Level42: Thanks for the offer but I'm in the US. My work has a large-ish site in the Netherlands, so maybe someday I'll get sent there... Tried a few things based on above suggestions: - Holding OPTION during power on did not change anything - still dark colored screen - Left system on for about 20 mins and checked for heat. Some chips were warm (in descending temp order): - CPU, uncomfortably hot after touching for about 20 seconds - Antic, warm, not as hot as CPU - GTIA, warm, not as warm as Antic - OS ROM, slightly warm all other chips (PIA, Pokey, Basic ROM, Freddie, RAM, MMU) were cold/room temp. Sniffed all around the board and no odd burn smells. No bulging or leaking caps. No home modifications, stock board with what looks like a couple of factory reworks (pink & purple wires I've seen in pix on other 130s). The only PS I've used is the Atari one that I have for my 800XL. Definitely no C64 9VAC. I've ordered RAM and sockets, so will wait for those to arrive and see what I find. I am hopeful this is the problem. Wish my 800xl had socketed mem chips I could borrow to quickly test. While waiting, I am pondering doing the bank swap just to see what happens ( Worth it? Maybe interesting side note, all the pix I've seen (and my board also) that has a single non Mt RAM chip is always in that first position (towards the rear, left edge). I have done due diligence and watched pretty much every YouTube from Flashcatjazz, GadgetUK164 & JaysVintageJunk (probably forgetting a few) and reading all the old posts here that might be related. Completely unrelated: If anyone has run across an 800XL with Rambo and 4 momentary round push buttons (2 red, 2 black - standard radio shack) wired to do the 1200XL function keys - let me know. That's my childhood A8 that I stupidly let go of in the 90s.... Along with an MIO, USD 1050, Happy 1050 & screaming 2400bps modem.

Thanks Level42! Yes, 15 of the 16 are Mt chips. I got your list from another thread already open and have been doing the ebay searches. LIke everything on ebay, its been a mixed bag of results... I suppose this is part of my penance for having gotten rid of all my original A8 stuff back in the 90s... lol

Additional info: Checked voltage = 5.16v. P/S runs fine on 800XL. No chips are hot. The CPU gets a little warmer than cold. Touching all 16 ram chips and none of them had a discernible temperature difference. I only had it on like this for 3-4 mins max. Wait longer? Video is stable. Just a single color, always darkish (dark green, dark brown/red). there are vertical stripes but those were there when everything was working. I'm using chroma/luma into a svideo->vga box. This setup (PS, A/V path, A/V Cable) was working fine before & still works great on an 800XL. I've seen a number of posts that indicate "130xe with micron memory = replace it all, its crap". Also, seemed like the most likely component to decide to work and then crap out; possible after having not been used for years (before I got the system). Since everything was working fine (and the power supply does not look like its a culprit), I'm thinking that this probably a single component failure... probably.

Greetings, Just got back into A8 after a long hiatus. Got a 130XE a few weeks ago. Had some bad trace on the keyboard mylar, but I fixed that. Otherwise was working fine. Turned it on and got a solid brown/red screen, no booting "clicks". Sometimes the screen is solid dark green. I've reseated and swapped with a known good CPU - mainly because that is the only chip socketed on this board (rev 5). It has 15 pieces of micron memory and 1 nec (based on what I've read in other posts, this was a likely factory fix?). i have a multimeter but not any logic probes, so I'm resigned to swapping components blindly until I get it fixed or no longer fund the endeavor (or break the board is also a possibility I suppose). Is this a logical order to tackle this? : - memory - mmu / emmu - freddy - gtia - antic I'm scouring the existing AtariAge posts for help, but would appreciate any advice. I saw a reference to swapping the banks by changing to resistors (R110 & R111 ?). Any specific components I can measure with a multimeter that will point me in a direction? What is a good current source for the RAM? There are a lot of dead ebay links in the forums. Thanks!

I know this thread is somewhat old, but in case someone else runs across this (like I did) trying to figure out the best way to connect their Atari to a VGA LCD: I tried 3 other adapters that did not work before finding this thread and trying the one that Gunstar recommended (Ambery). That adapter is the only one that has worked correctly for me. The other ones produced horrible output (missing color, torn, shaking, etc). @Gunstar: Thanks!!