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Posts posted by hueyjones70

  1. I have an 800XL that doesn't respond to the joystick down in Port 1.  Joystick works ok in port 2. Have resoldered the joystick input connections and no change.  I have no idea where to start trouble shooting.  Is there a particular chip/pin that carries that joystick signal?

  2. I don't know why this worked but there were 3 empty spots for resistors, capacitors, etc so I installed jumper headers in those spots and when I added the jumper to L12 I got composite video.  There is no part listed for L12 in the manual and L12 is not mentioned in the instructions for the Super Video 2.1 upgrade.

  3. I have almost done a successful SV2.1 on a 600XL.  I say almost because I have luma and chroma but no composite.  My composite appears to be about the same as chroma only. It appears that there is a trace for composite to the monitor jack.  I am wondering if this is not actually the case and If I need to run a wire from somewhere to the composite connector post on the monitor jack and eliminate the aforementioned trace.

  4. I have been working on a PAL 600XL. It came with the monitor jack and all of the extra video circuits were populated.  I am only getting black & white output and I was informed on another thread that this is normal for PAL machines.  Will a UAV output color even on a PAL machine.  I remember working on an 800XL and getting color output but I don't remember if I did a UAV on the 800XL or not.

  5. Thanks for all the info.  I installed sockets for the ICs I had removed and with a working SALLY the computer is partially working.  I cannot get chroma.  I ran the wires to the monitor jack according to the instructions for the SuperVideo 2.1 modification.  I cut the trace that grounded chroma.  The Luma is very sharp.  Is there another point besides the junction of resistors 123 and 124 that would give me a good chroma hook-up.  Is the problem possibly because of using a PAL computer on a CRT monitor.

  6. 1 hour ago, BillC said:

    When you put in a BASIC socket you will probably want to use a 28-pin socket, since you have the 600XL PCB version that can use a mask ROM or an EPROM for BASIC, this would allow you to install an 2764 compatible chip with Rev.C BASIC on it if desired.


    The soldered jumpers to select are just to the left of the capacitor behind the BASIC socket, indicated by arcs in the silkscreen similar to below.






    I would like to know more about this.

  7. There are pictures of the PCB, I have already started taking out components so that I can add sockets as I trouble shoot the problem.  the only socketed chip was that weird one that fits in a 14 pin socket but only has I pins.  I had taken out the OS ROM and BASIC.  I added a socket for the OS ROM.  I will get some more work done tomorrow.  


    Update: I may have found the problem, the 14806 is bad.  I need to solder in sockets for the ICs I removed and retest.  If the computer works I don't know if I will continue to add sockets or not.



  8. I just acquired a PAL 600XL and it has the video monitor jack and it appears to have most or all of the video components installed. Is this normal for a PAL or has someone modified this machine? The machine is currently not working and it is totally unsocketed so I will have to do some work to.

  9. On 2/1/2020 at 10:15 AM, DrVenkman said:

    The color pot may be dirty or developing cold solder joints. Touch up the contacts on the PCB with a soldering iron, then spray Deoxit or another cleaner into the pot and cycle it end to end a few times before allowing it to dry.  After that, check again. If that’s not it, there are a number of components in the circuit that might be bad or going bad that can cause voltage fluctuations and weird color effects. 

    I did the Deoxit thing and the problem seems to have been eliminated, good call. Thanks.

    • Like 3

  10. I have a 130XE that changes screen colors. This is not the color change that comes with a long period of screen idleness.  The shades of color change just a little every few seconds. The opening blue screen may take on a slight purple hue and then turn to a dark blue. I haven't timed it out but it seems to be about the same time interval on each shade. I wonder if it could be the color resistor. I have searched the forums and haven't found anywhere that anyone else has written about a similar problem.

  11. On 10/30/2005 at 5:38 AM, SeaGtGruff said:

    Here's my short program to display all 256 colors at once on the Atari. Since right now I can't connect my real Atari, I'd love for people to use this on real Ataris and do screen captureS (NTSC, PAL, and SECAM), then post the screen captures.



    12 FOR N=0 TO 4:PLOT 5*V+N,0
    13 DRAWTO 5*V+N,191:NEXT N:NEXT V
    14 D=256*PEEK(561)+PEEK(560)
    15 FOR N=1 TO 16:READ V:POKE D+V,143
    16 NEXT N:FOR N=0 TO 25:READ V
    17 POKE 1664+N,V:NEXT N:POKE 512,139
    18 POKE 513,6:POKE 546,128:POKE 547,6
    19 POKE 53248,40:POKE 53249,208
    20 POKE 53261,255:POKE 53262,255
    21 POKE 53266,0:POKE 53267,0
    22 POKE 54286,192
    23 GOTO 23
    24 DATA 16,28,40,52,64,76,88,102,114
    25 DATA 126,138,150,162,174,186,198
    26 DATA 8,72,169,0,133,203,104,40,76
    27 DATA 95,228,8,72,165,203,24,105,16
    28 DATA 141,26,208,133,203,104,40,64



    Michael Rideout

    I am glad I found this.

  12. Thanks for that information, I did check another of my 130XEs later and it didn't do an extended ram test either.  The problem computer seemed to do OK with DOS 2.5 and only acted up with MYDOS.  I switched the resistors and did the memory self test and nothing came up bad and when I booted with MYDOS almost everything was OK but the RAM disk showed that there were two programs in memory that I have never seen before.

    130XE RAM Disk.jpg

  13. Started working on a 130 XE and I thought everything was fully functional but when I do the self test there is no check of extended ram. When I boot with MYDOS and check the RAM disk, the computer prints out 5 or 6 lines of letters , symbols, and numbers; then it tells me there are just over 2000 available sectors. Does this mean that I have bad extended RAM or could the problem be with the MMU or with the Freddie.

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