seastalker

Ok, I found that setting. Not to make this 600xl thread now a multimeter tutorial, but does this mean to put one probe on a socket or installed chip's corner leg (the shoulder) and to place the other probe onto each other pin of the chip/socket you are on?

I just got a TI99/4a exhibiting the same behavior. I will try the same above testing and fixes.

I have this multimter: https://www.amazon.com/Cen-Tech-Digital-Meter-Voltmeter-Multimeter/dp/B001RSREKI/ref=cm_cr_arp_d_product_top?ie=UTF8 I don't have the audio icon normally used for continuity. According to https://sciencing.com/use-centech-digital-multimeter-6101228.html there is a trick to check continuity via resistance. I think I just need a better meter and may check shops today.

Tried swapping PSUs and power outlets but the loud buzz remains. Sprayed the channel select with cleaner and jostled about 10 times so when dry I'll try again. I suspect it is something internally. I will open it after I get through the 600XL I'm working on, but it may be a great candidate for the new S-video mod and RAM upgrade and get off of RF completely.

... AH! There's that SELF TEST now! :)

Cross referencing another related part of this topic: http://atariage.com/forums/topic/279498-odd-600xl-issue/?p=4068795 I fixed my XEGS this week AND got one 600XL working with the help of an Antonia board. Only NON-satisfactory part is I'l always wonder what remains wrong with the board without Antonia's crutch. I'm going to do my best to fix this other 600XL. I'm a noob with a multimeter but found some tutorials. I also picked up a NIB digital logic pulser for a steal locally- my next thing to learn. Multimeter set at 2000k for resistance testing, I am putting one probe in the holes on the left of the board and then poking each pin of socketed chips. I also tried R36 on both boards and get very different results. Also the pads where the 64k upgrade went somehow wrong. Only thing is, it dawned on me that I'm working on two boards with issues, as the 'working' one has its issues lipsticked over by Antonia. I have the 600XL Computer Field Service Manual Rev 1 but where do I find the intended values of the pins of smaller chips and say R36 so I know how to make heads or tails of the numbers the multimeter displays? I'm learning a ton this week.

Thank you DrVenkman for the manual. I did find it prior and have been reading it. Now I hope to find EXPECTED multimeter number values since I'm working on two boards with problems without a perfect 600xl. Also, please see the attached pic - I added to Nezgar's labeled white boxes with my own unlabeled ones. I can confirm the Atari still goes to boot screen with ALL white boxed chips removed! That is not to say that is ideal or not yet as I DID notice that when I hold option it no longer boots to the Self Test. If the Self Test is stored (likely) in either the BASIC ROM or OS ROM chip, I suspect that would be a natural side effect and would guess I'd have to configure Antonia's settings which would include that. With no Antonia manual, I have yet to research that. That said, it is AMAZING to me how much of the A8 can be removed and still boot with Antonia! THAT it also replaces my need to get a new CPU or DELAY is also fantastic... AND... remember that "bad" ANTIC? I learned never throw ICs away as they may be misdiagnosed. Though a working 600xl did not accept it, for whatever reason, putting the original 'bad' ANTIC back in actually works now (at least to get to the boot screen)! Maybe Antonia bypasses some ANTIC pins or features and only used 'just enough' ANTIC to work? I hope Simius sees this thread as he would be the authority on Antonia to answer this. I also need to test joyports and SIOtoPC functionality, but with all the above chips removed, I'm happy for anyone's ideas of other tests to run so I can confirm these ICs, though nice to save in protective anti-static storage, removing them won't hinder functionality beyond what can be observed by a simple boot up screen.

[egg on face] - yes... though I know the difference well, the naming scheme has tripped me up before when I go too quickly. Why they named both starting with 'compo" instead of sounding completely different in name is beyond me.. except to trip us up like now.

I'm actually having a hard time trying to find an image of a 600xl motherboard with all the chips labeled. Has anyone who has stripped down an A8's redundant IC chips listed the IC by number or by picture which I can take out and store away? I'd figure the two ram chips that you WOULD replace when doing the 64 upgrade. EDIT: I may have an answer soon- I am able to at least boot into the ready screen with full sound with the antonia board with almost all of the small chips removed! I'll complete the list with pics but only problem now is holding option at power up does not initiate the SELF TEST. Which IC chip stores that? Then, would I even still need that if Antonia has built in configurations?

This one has ZERO socketed chips. I do have a U1M on order but it will likely go in an XL with Svideo (and maybe Sophia too). The XEGS will be more retro casual with stock everything - Only component out (no UAV, Antonia, Sophia etc). The XEGS at least IS on a CRT with light gun and SIO2USB cable. Until I get some Hakko solder/desoldering gear, I dare not butcher the XEGS.

Hi! Just wanted to add praise for Simius's Antonia 4MB board, and it's surprising added benefit to me. It tested well on one machine. Then, sheer joy! I was gifted a 600XL with a bad ANTIC (CO21697), CPU Sally 6502C CO14806 and CO60472-D (Delay). EVEN when I replaced those from known working ones it was all bad still with odd black striped screen. ANTONIA+ spare ANTIC and Delay fixed everything in this case. Some may be ONLY for the U1MB solution but in this case, ANTONIA is perfect. The price now also eats what I would have paid for a new Sally CPU, I now have an extra MMU, and after research of what else I can pull out RAM/Roms as spares! Plus, after screwing up what is said to be simple (64k ram upgrade), this ANTONIA also removes my need to but a soldering iron to the delicate board and the minor expense of 64k upgrade chips. Huge thank you to Simius for this product!! Not only great for many A8s, it is PERFECT for the above story. QUESTION: My 600XL is fully socketed. Which redundant ICs may I pull out and save for spares/another A8 that Antonia takes over for?

UPDATE: Well, my working 600xl I posted in another thread I buggered (only temporary I hope) doing a 64k upgrade. HOWEVER, my original buggered one I now have working! Anyone care for detective work? Based on my OP, I put an Antonia in on the chance it may bypass part of the board where one of flashjazzcat's mentioned problems may be and it worked! Plus I didn't have the ebay a sally CPU in the process. Needless to say, I 'borrowed' the antic and the CO60472-D (Delay) from the working (formerly til today) and it fired up right away! A twist of the color pot and purple went to blue! So, any tech detectives knowing Antonia specs care to guess what my underlying issue is and what caused it? A. ANTIC (CO21697), CPU Sally 6502C CO14806 and the CO60472-D (Delay) WERE BAD. B. Replacement ICs gave above screen, but Antonia 4MB (replacing CPU and MMU) fixed everything! Does whatever magic the antonia does via bypass reveal what was broken?

RE: 64k upgrade - After a 100% successful XEGS microswitch repair this week I went for the 64k upgrade on the 600XL. @manterola - your picture looks different than other's upgrades. Maybe at some point I will try yours. I found a never used car stereo connection and cut a wire to strip and snip for required lengths. I folded back and cut some extra copper strands to thin out both ends. As per the start of the guide in this thread: http://atariage.com/forums/topic/183694-600xl-64k-upgrade-pictures/ I did the mod but it did not work: I got a black screen. I then thought maybe some part was bad and tried going backwards; from another tested 600XL with good chips to swap in, my plan was slowing "undoing" what I did until I got the Ready screen back. I'd unseat the chips with wired legs and leave them floating in the air (not touching anything) on its board-connected wire. Each 'floater' would get an original chip with legs intact put back in each spot. Even R36 resistor leg was but back and the old 16kb chips. Only time I got the blue ready screen was when I tried one 16k ram IC with one of the newer ones to make it 64. That only worked once and now I'm at black screen. Restoring everything the way it was still is black screen, even if I try the antonia board to bypass some things. Anyone have an idea what might be buggered? (other than me) . .

@Kyle22: Thank you for the confirmation. The change when you disconnect the keyboard had me thrown. I've successfully fully restored my XEGS with 4 brand new Alps switches, and fully cleaned. I really like the look of this in my collection. I was XL all the way so this is my first XE (I don't have much interest in getting a 65 or 130XE unless it was a steal)

@manterola - Does wire gauge matter in these things? If so, what range should I stay within? I have lots of spare new wire.

Yes, I guess that minor detail is very important. I have some Atari/Commodore cables with composite, separate chroma/luma and even one with a S-video connector. I'll experiment a bit and report back.

Looking at a 600xl now... is the 5 pin din the pads just behind the channel switch? I'd love to remove RF switches off everything I can, but often a basic solderer and solder sucker just wont cut it. I'm saving up for a Hakko set so I can soon remove ICs like a pro.

@JR Slightly off topic, but I now have an Antonia and tested it and it works a charm as far as in Self Test. Anyone used to stock only will be surprised to see the LARGE blocks in Mem test- reminds me of the board game RISK with 10 men being represented by the weird shape pieces. I look forward to testing the biggest demo scene stuff. You mentioned the 65C816 CPU replacement of the Sally 6502. It didn't come with a manual and didn't find much YT video content about this. How does this CPU differ and compare and what new functionality does it add?

David_P - That made me laugh out loud. Imagine in Pitfall having two dedicated screens for the above ground and hopping scorpions on two 4k tvs below. On a more serious note- I have been testing the Sophia and it is AMAZING! Thank you Simius!! At first I put it on a Dell monitor and it had bad picture due to the screen's limitations. a 1080p Samsung LED 40inch showed NOTHING. Then on a newer screen (though not 4k), I got the best Ready screen I've ever seen. I could even toggle the remote's 4:3 or 16:9 aspect ratio button and games looked true in 4:3 as remembered, but ALSO looked great in 16:9 almost as if they were programed that way. That says a lot coming from me who is a stickler for proper aspect ratio. Didn't look stretched- it looked scaled even if that wasn't what it was doing. VERY happy with it AND my UAV for my machine on a CRT. Question: Deciding on Sophia's permanent home- likely a 600XL since mine is NTSC and only has RF out. IF I do that, what are my audio options? I'm open to intrusive options, but if the sound improvement is minimal, anyone have a quick easy RF Out -> Audio Out via RCA or headphone jack plug out option?converter?

Ah, great piece of info. So I should add that that would mean trying to load a larger than 64k .XEX (or .ATR, etc) file from RespeQT software via SIOtoPC usb cable on a stock 600XL/800XL won't work or any flash cart that is DRIVE emulation. You would need a ram upgrade. However, The!CART flashcart is actual cartridge emulation so loading from that device would work.

Well, I swapped out the START, SELECT, OPTION, and RESET micro switches one at a time and testing each new switch before moving on to the next. They all are working fine now. I'm glad I ordered extra as one of them felt squishy vs the others being nice and springy. So I had to redo the one squishy I didn't notice until testing. Great simple lesson to remember if anyone else does this - test the switches' feel BEFORE soldering it to the board. Saves time and better safety keeping heat off the board. This action may have fixed another issue... @DrVenkman and everyone: the buttons work but as I never had a XEGS and am not used to having a built in game (I was an 800xl only type before), one question about default XEGS behavior: Is this the way the machine was made when no cartridge is inserted? POWER ON = Missile Command POWER ON with HOLD START = Blue screen with BEEP and no "Ready" nor cursor. POWER ON with HOLD SELECT = Ready Prompt POWER ON with HOLD OPTION = Self Test RESET = Missile Command RESET with HOLD SELECT = Ready Prompt EDIT: I should also add that I tested RespeQt software with it, and I must hold down SELECT when powering on if I want to load an ATR image through my SIO2PC cable. On my XL I just power it up. I'm hoping I don't have a reverse polarity issue with SELECT. EDIT TWO: ** A Youtube video had someone demonstrate the XEGS where he showed that if the KEYBOARD is plugged in it boots to the Ready prompt and if you UNPLUG it, then it boots into Missile Command! I never knew about that quirk. Maybe my system now is back to 100% intended functionality?

@goldy: I saw your link which is very helpful! I was excited to see the type of switch and how they work prior to yanking on them willy nilly. Also positive was the chance of not needing to desolder if an alternate fix exists. I have replacement switches, but tried your method first. Unfortunately in my case, the problem remains - my select and option buttons are still buggered. With the system also toggling between booting to self test/missile command/self test/missile command, could I maybe have a failing PLA chip? (Wait, maybe lowercase text on diagrams is throwing me- I think PLA is C64 and PIA is Atari)...

I remember long ago the subtle compatibility issues with some 400/800 running on XL machines unless you use a translator. The XEGS was built with 64kb RAM (much like an 800xl), yet I have seen mention in flash cart discussions concerns of if such and such device can play XEGS titles. Though the hardware may be different slightly with the Freddie chip built in, what issues (if any) are there with XL compatibility? Is it some XEGS carts don't play nice with XL machines? 128kb file size issues? Some XL titles may not have 100% compatibility with the XEGS? I've been curious about this. Thanks!

Asmusr, your link shows a good pin-out comparison. On a TI99 USA model, pin 5 is not connected, the others match except pin one is 12v power instead on Svideo Luma on the Atari/Commodore. So, If I have the separate power cable plugged in, the TI99 powers on, but I'm using an Atari Commodore video cable, how does the 12v expectation on the TI99 factor in?

I have ebay converters that make a 1999 CRT tv accept the RF adapter output of older systems like the Atari 400. My recent 400 purchase showed me RF video fine with internal speaker working and all keyboard buttons working beautifully. The audio however is very buzzy and thought someone here may know some tests or grounding. Down the road I may look into the mods to bring this up to 2018 standards but first wish to test and troubleshoot it in its natural state.