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bernie

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Posts posted by bernie

  2. Posted · Edited by bernie

    Have you removed and reseated all the chips on the CPU board as DrVenkman suggested? Also removed and reseated the CPU board itself? Removing and reseating chips worked for me on a 600XL (I also lightly sanded the chip pins with fine grit sandpaper). Usually socketed chips are a good thing, but not when it comes to decades of corrosion.

     

     

    I just ordered a tested CPU from eBay. Will remove the chips now! I did notice that the cooper was starting to peel off the back of the PCB on the circuit board.

  3. Posted

    Whilst I would agree that it might be a bit of a stretch calling it inexpensive, it's totally worth it considering the video quality it puts out. Most of those cheap-o composite/svideo to HDMI adapter are total trash with terrible image quality and many have a locked 60Hz output regardless of input which kills smooth scrolling with PAL hardware.

     

    Looks great, but I'd love a cheaper solution.

     

    Are there any modern computer monitors that simply take SVID or composite?

  4. Posted

    I need to swap out what I think is a bad CPU board.

     

    1. Which CPU is best/most desirable

    - Rev 5 or 6

    - 6502, B, C

    - CTIA or GTIA

    - Another one (like the super color CPU card) but that works with NTSC?

    2. How can you tell pal from NTSC cards apart?

    3. Are there incompatibilities with motherboards or do they all work the same?

    4. Are the 400/800 ones the same?

  7. Posted

    If you haven't doen so yet:

    Open the 800 up and check if the RF cable is properly connected inside.

    When you're in there anyway check for a broken RF cable with a multimeter. Do not over tighten any screws when you reassemble the case.

     

    Thanks. The RF cable is properly seated.

     

    The issue also exists via the monitor out

  8. Posted

    Thanks. An oscilloscope is more than my current skill set and I currently don't have another 800 :/

     

    I currently have the case off the atari with the cartridge cover switch rigged.

     

    It's almost 4am in Hawaii, so I'll look into it tomorrow.

     

    There is a section for "snowy screen" in the service manual (5-3) I will also change the voltages and check the ground connections of the RF module (which hopefully I will find!) But the only guidelines are "is the RF module mistuned or defective" -> Repair

  9. Posted · Edited by bernie

    Given the problems you're having across multiple TVs, I'm pretty sure you've got an issue with one fo the main chips, probably ANTIC, GTIA or the 6502.

     

     

    Correct. Second TV works fine for cable.

     

    My understanding is that all those are on the CPU PCB- correct?

     

    Looking at the field manual and looking for video out functions I found the following info:

     

    The functions of the CPU PCB according the to the atari field manual are to:

     

    Generates video signals to be processed by the motherboard before they are sent to the RF module on the Power Supply PCB

     

     

    The relevant functions of the motherboard are:

    Receives video data from the Central Processing Unit PCB, converts it into a composite video and routes it to the power supply PCB.

     

    Motherboards route the Composite video signals (COMP CHROMA, COMP LUM, MOD, and COMP VIDEO) to the Power Supply to build the RF video output.

     

    Powersupply:

    The RF signal is generated in both the 400 and 800 Power Supplies from the MOD signal received from the motherboard. It is routed through the A203 RF Module to develop the RF output through 3203.

     

    Is there a way to isolate?

  12. Posted · Edited by bernie

    Your adapter for RF is RCA to F connector? And the long black cord from the 800 connects to that and you tuned the TV to channel 3? Make sure tv is not auto scanning and you manually picked standard and not hd signals.

     

    Correct. I had 2/3 pre-programed from when I had cable plugged in directly and nothing. I switched to antanna mode and unfortunately even when trying to add channels 2/3 manually my TV does not find a signal to add them. I will try on my friend's TV tonight.

  15. Posted

    I can almost guarantee you have the wrong video cable... There are several computers that use that same cable (Commodore VIC, C64, TI994/A, Sega Genesis, Atari, and even generic MIDI) and wiring is different on most all of them.

     

    It may be. I'd be confident of that if I was able to get a signal from the RF though...

  16. Posted

    One thing you can try, is press ctrl+2. It should generate a very annoying buzz from the speaker rather than just the normal keyclick. It seems like the overall machine is working, given the fact that you are generating keyclicks.

     

     

    Thanks for the tip ctrl+2 does generate a very annoying buzz.

  17. Posted

    In summary, here is where I am now:



    The 800 powers on (red light) and if I remove the cartridge (I tested with two) I hear clicks when I press the keyboard (in memo?), so something must be working...



    The monitor->composite cable gets a "no signal" (and no sound comes out if I hook to stereo) I tried plugging in the audio part of the cable into a stereo and I hear some chirping when the atari is powered on and off.



    Through RF (via RCA->Antenna adapter I got today) I get no signal on my TV



    I unplugged/reseated Ram/combination of RAM in the back



    I have tried several cartridges in the left slot with the cartridge door closed (so the power light comes on).



    I tried several different power adapters



    I tried a basic take apart, and there is no visible damage/spillage internally



    -----------------------------



    What I plan to do:


    1. Test power adapters with multimeter


    2. Test internal voltages



    ------------------------------



    Questions:


    1. How do I unplug the keyboard


    2. Where should I test internal voltage


    3. Since I'm getting the power light, and when I press the keyboard with no cartridges I get sounds to indicate keypresses; something must be working. How can I isolate if it's the PSU board, or the main board, or the personality board?


    4. Anything else I should try?


  18. Posted

    Do you have the 5-pin DIN to 4 RCA plug version of the cable? Have you tried connecting each of the 4 RCA plugs to composite video in on your TV just to make sure it isn't wired differently than expected?

    No, I have the three RCA version (with two audios joined)

  19. Posted

    I'm sure you have tested the power supply brick. The plug should be about 10.6 volts AC with no load on it.

    It supplies 5 v dc, inside the computer I think. That's with a NTSC power brick.

     

    I haven't. I tested with 2 power supplies but I can test with my friend's multimeter tonight. Where should I test inside the computer?

  22. Posted

    Let's see. You have the ROM card in front slot, at least one RAM card in behind the ROM. You have

    the cartridge door shut. Your cartridge is in the left slot. ? there is no RF port, where you gonna

    get a RF output? You ordered a RF adapter. Does that provide RF from the 5 pin monitor port?

     

     

    Yes. I have 48k of ram and the the ROM in the back (which I removed and reseated), a cartridge in the left slot (tried several), and the cartridge door closed (so the power light comes on).

     

    I have 5 pin monitor port to composite (RCA) lead and get no signal on the TV.

     

    If I remove the cartridge, and reset, If I press any of the keyboard keys I hear click (I assume I'm in Memo).

     

    I tried plugging in the audio part of the cable into a stereo and I hear some chirping when the atari is powered on and off.

     

    I am waiting for adapter to allow me to plug into antenna in (c2/3) on my TV.

     

     

     

     

     

    I

  23. Posted · Edited by bernie

    I just bought an atari 800 of craigslist in "unknown" condition.

     

    I purchased a monitor->composite cable (that my friend tested) and plugged it in to my Vizio 65" LED tv. Unfortunately I get a "no signal" (and no sound).

     

    The 800 powers on (red light) and if I remove the cartridge (I tested with two) I hear clicks when I press the keyboard, so something must be working...

     

    Any ideas of next steps to troubleshoot? I just ordered an RF adapter so that I can plug into antenna switch.

     

    Unfortunately this is the only machine I have that uses Composite input.

     

    Thanks!

    B.

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