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smalltownguy2

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Posts posted by smalltownguy2

  2. Posted

    Thanks for the helpful replies, everyone. I have a couple of spare woodgrain TV's laying around, so I think I'll put this together as a "retro package deal" with a fully working system and a TV to play it on and price it at $125. Should go quick, I would think.

     

    • Like 1

  3. Posted

    Co-worker handed me an Atari 2600 woody with 38 games (4 doubles). Wants me to sell it for him. What's the rule of thumb when calculating how much to ask for when you bundle it all together? I mean, I know what the pieces total to in price charting, but surely it's supposed to be sold at a MUCH lower price than that when sold all as one lot, right?
    Just shooting from the hip, I'm thinking one third of the PC total.
     
    What say you guys?

    2600-system.jpg

    • Like 1

  11. Posted

    I DID measure the power supply, or at least I believe I did. I got 5v using my meter. But it must have been making a good enough connection for the meter, or maybe I read it wrong.

     

    Yes, the power for the VIC chip is rectified from the 9v line. Learned that over on the Lemon forums. Once I figured that out, it was easy to see that I was missing 5v from the power supply.

    • Like 1

  12. Posted

    Success! I was able to inject my own 5v from an arcade power supply and the system booted.

     

    Interesting note: I believe the fault in the OEM power supply was a broken wire at the plug. When I was testing wires for continuity, the 9v lines were great and the brown (5v) line was good to the plug. The blue line however, showed intermittent connection at the plug. Wiggling the plug made the multimeter beep. Aha... broken connection inside the plug.

     

    I went ahead and soldered some wires to the 5v and gnd rails on the underside of the pcb and she fired right up. Sweet!

     

    Looks like I need to buy a new power plug connector.

     

    post-42663-0-00962800-1521112184_thumb.jpg

    • Like 2

  14. Posted

    Replacement VIC chip was swapped in, and issue persists. Same black screen. I only left the machine powered on for about a second or two, because I didn't want to risk burning up the new chip if there was some sort of voltage problem.

     

    At this point I only have 1 option left currently: try swapping in external power. I will fire up an external 5v power supply and tap it in to see if that changes anything. Based on how I was measuring voltages before I don't believe the power supply is bad, but testing with another known working power source will rule that out completely.

     

    If it doesn't boot with externally provided 5v, then my path forward will have to involve a known working C64. I will need to begin swapping chips to narrow down where the failure is. I DO have a local friend who has a C64; I'm just not sure if he'll loan it to me for troubleshooting or not. There is a swap meet coming up next weekend that could be used as a common meeting point though, so maybe I could make some progress there. If not, I may need to purchase a known working C64 to finish the repairs and then re-sell it once I'm done.

  21. Posted · Edited by smalltownguy2

    I poked around a bit more on the board this morning before going to work. The VIC does get pretty warm the longer the unit is left on.

     

    Measuring voltage around various places on the board, I'm getting .408v pretty much at pin 1 of every chip on the left side of the board: ram, rom, CPU, logic, all of them have .408v. This is the same voltage I see at the LED as well.

     

    The VIC chip socket has 5.04v at pin 1, and the VIC shows input voltage of 5.04v when inserted, as do the surrounding logic chips inside the cage.

     

    Removing the VIC, I get nothing on the TV when turning the board on and off. None of the chips on the left side of the board have any voltage then either. Inserting the VIC, I get "black screen," and all of the chips have .408 v again.

     

    I'm thinking at this point the issue lies with a failed VIC chip. Something has to be dragging down the 5v line to .408v, and I think this might be it. Is there a way to check this with a multimeter?

     

    I'll check into buying the PLAnkton (EDIT: may not be needed....)

     

    I really wish I had a working unit nearby for chip swapping. I'd feel a little less blind then.

  23. Posted

    I tried the rapid-fire on-off method, no dice.

     

    Looks like the 5v drift is the major concern on the OEM power supplies, so I'll temporarily disconnect the 5v rail from the OEM PS and pipe in my own 5v from an arcade switching power supply I have. That way I can be sure I'm feeding a nice stable 5v into the machine.

     

    What are the best options for a replacement PLA, should I need to go that route?

  24. Posted

    I've been doing some reading on Ray's site, and it appears the next logical step for me would be to get a known working power supply and test from there. If the machine doesn't fire up with a known working power supply, then the next logical steps would include having another known working C64 with all socketed chips to start testing for suspected failed chips, one at a time.

     

    Any reason why I couldn't fabricate my own test power supply by tapping in a 9vac power brick for the 9v line and a 5vdc power supply for the 5v line? Or should I hold out for a replacement PS?

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