TEBL

Thx, capacitor was lifted at some point though possibly not at the time of picture. Replaced L6 with wire as well. Tried the other UAV I had, no changes there either so back at looking for other things. Installed UAV in the other non-freddy I got that have just a slight hint of bars, couldn't tell a difference before and after so removed it since it has a low shield so just not my luck. Think I just have to wait on random parts before I end up taking a hammer to the damn things :-)

Thanks for the assist tf_hh though no luck so far, changed all electrolytics and added the changes you referenced (replacing l3/4 with wire and bypasd for freddy). Unfortunately I've still got the same thing so, leaning towards something with the pal side of things so ordered a new oscillator and a new inductor for that general area. Not for any other reason than running out of things to try replacing.

Hmm... Finally got around to installing this in an 800XL with the Freddy chip (PAL region), seems that I've still got my original problems intact after installation (vertical bars, sort of zig-zay-y). Only using composite since that's what I have available, the good news ofcourse is that it didn't blow up on me. Ground pad on UAV cut, wire directly to pin 2 on monitor port. Any ideas of where to go from here? Oh, was I not supposed to keep the beads as part of the new circuit?

Looking good, think I would have reduced the complexity on the ROM idea and just put in a Zif-socket for the first version. Could also pick up a cheap RIOT and use that in the beginning till you get the emulation down - that way you're not trying to do everything at one. Just my 2c, it's incredibly how minute detail quickly changes things into a garbled mess.

Trying to debug another 800XL that has issues with the color circuit. Yes, it's another one - ordered this one as a spare so I had something to check against while fixing the other one, but when I got it I found that this was an 800 XLF revision 3 board instead (actually says XLF on the actual board). With an entirely different problem related to colors, what rotten luck :-( There's some noise in the color signal and while it looks strange, the adjustment of the color pot also has a wierd effect that I'm not sure if is normal since the other one I have is not an XLF. I get vertical banding, when adjusting it seems like I'm opening colored curtains before it goes B&W (see youtube clip below, some interference with camera) instead of shifting the color spectrum. Have been trying to match this to the schematic I found by SOBOLA, but I think there are quite a few changes leading up to my revision 3 board since his revision 1. Not sure if it matters, but I've been looking at the Phi 2 signal though it might be a totally wrong place to end up. Schematic connects phi 2 for ANTIC behind 74ls08 with GTIA getting signal directly from SALLY - the board however connect POKEY, PIA, ANTIC and GTIA via 08 pin 3 only leaving FREDDIE connected directly to SALLY pin 39. Is this normal, I could understand it if they were simply bridged but seems like completely separate on PCB so thinking schematic doesn't match up.

I use the real hardware mostly, nothing beats the feeling of proper 80s plastic creaking under your fingers while sitting way too close to the TV. If you're in it because you like messing with the electronics, trying to keep it alive just one more year then go physical. If you just want to play the game, then emulate away and think no more of it :-)

Haven't verified any further than looking at the datasheet, seems to match the specifics on the ones I'm using. I just used the list on http://www.minuszerodegrees.net/memory/4164.htmand tried to find whatever was cheapest and ordered extra just in case of bad pulls. My machine had 4264 memory, but found a post online that 4164 could also be used since the Atari most probably never used the extra function it offered. Anyway the only matches I found were MT4264, and they were the crappy ICs I was removing so 4164 it was and so far it works for me.

Well, still have no idea which part fixed it since I more or replaced everything in the voltage doubler circuit that I had access to so it might have been one of the capacitors, but still assuming the fix was replacing R45 with a 47K since that was the closest I had on hand. Looks like crap with all those monolithics and a ceramic bent every which way to fit the holes, but it works and hopefully I can get it back into it's case before deciding to do anymore with it. What do you guys do with unobtainiums like these caps? Still, anyone have the ability to check the proper value of R45 and an opinion on wether I should leave the 47K in there?

Looking at the board, according to the schematics I'm supposed to have 33k resistor at R45. The one on there has color bands indicating 270k though I can't seem to get the multimeter to get a reading on it. Is this a fault in schematics and service manual, or was it changed? Hmm... strange that I can't measure it.

Hmm... Have gone through that entire section of the PCB without finding anything not matching the schematic, it does however look strange that colours appearantly repeat instead of differing - whatever I adjust it to through R38 it doesn't seem to change the fact that I have two sections of the spectrum that end up the same. Spent an evening stabbing at it with different implements. Regardless I still have no clue as to how the various colors are generated and at what point they could possibly end up the same. Aah, dammit... all this Atari stuff is making me miss my C64, and I'm posting more or less to myself so time for bed.

Thanks, don't think I understood the conclusion of that thread unless it was as easy as a break between 6502 pin 3 and capacitor C44, but that at least gives me a new avenue of things to try out in relations to the area around R38 - so far I've only measured and tried replacing the actual pot without looking so much at the nearby circuit. Times like these I wish I had space for an oscilloscope, but gotta check the traces first :-)

Think I'm in the right place atleast, I believe these resistors in conjunction with the transistors create the colour part of the signal. I've tried mapping out where things go according to the schematic while tracing stuff based on continuity so some passive components may be drawn in in the wrong orientation. Can someone with access to a revision D do some simple resistor measurements from the pins on transistors Q2, Q4 and Q5 to +5V and ground, so I have something to compare it too?

Have been fiddling with an Atari 800XL I bought a couple of months ago from someone in England, so it's a revision D PAL unit that I'm using over composite (from retrocomputershack) on my LCD (no space for the old CRT thingies) with one of Lothareks PSUs. Have been looking at the posting on http://atariage.com/forums/topic/230225-colors-ntsc-vs-pal/to help debug some color issues I'm having, essentially the wrong colors substituted in the middle of the spectrum. I can adjust R38 back and forth and it'll either go totally out of whack or B/W, don't have a scope though so I've tried using small increments. The closest I get on the startup screen is what I can only refer to as DOS blue though my XLF, extreme jailbars aside, looks more like teal. I've replaced all 4146 RAM chips (mostly dead MT4246 originally), GTIA, ANTIC, 4050 with CD4050BE, PAL crystal, 2N3904 transistors as well as all electrolytics without any significant changes to the colors. Picture below is from SALT 2.05 running via a SIDE2 cartridge, have also tried using a basic script to show all colors and hues where I'm seeing the same "repeat" of colors in the middle. Anybody got ideas any ideas on how to explain this? NB! LCD works with ZX Spectrum, Acorn Electron, Commodore 64, Commodore 128, Dragon 32, Atari 520STFM, Amiga 500/600/1200 with some duplicates (which is probably why I've got storage problems). Never seen anything like it so I think it's something to do with the circuit.