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Amiga 500 repairs

Discussion in 'The Lounge - Off Topic' started by BosonMichael, Jan 22, 2010.

  1. BosonMichael
    Highly Decorated Member Award

    BosonMichael Yottabyte Poster

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    Well, I've unboxed the Amiga 500 in another attempt to repair it. The Joystick 1 port is having problems. Here's what's happening:

    Joystick:
    • button works
    • hold stick L, cursor moves up 1 pixel; release stick, cursor moves back down
    • hold stick R, nothing happens
    • hold stick U, nothing happens
    • hold stick D, cursor moves right 1 pixel; release stick, cursor moves back left

    Mouse:
    • connecting it causes Workbench bar to flicker between "Workbench release/free memory" and "Workbench Disk Special" drop-down menus.

    I was told that it might be an unseated/defective Gary or Denise. Those are no problem, because I can unseat and reseat chips easily. But if those aren't the problem, it's likely a soldered 74HC/LS157. And therein lies the rub...

    ...I can't solder. :(

    I've tried before (NOT on my Amiga!), and I end up causing (much) more damage than I fix. I simply don't have the dexterity to do it. Worse, I don't know anyone who knows how to desolder/solder.

    Any advice, either on the repair or the soldering?
     
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  2. jk2447

    jk2447 Petabyte Poster Moderator

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    I suppose you could try replacing the ports themselves . . . maybe. I used to suck at soldering until a friend lent me his cold soldering Iron. Not sure if its just me and my mate but I found doing it much easier and repaired an old radio just to see if I could. Sorry if thats not much help . . . . Jim
     
    Last edited: Jan 22, 2010
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  3. dmarsh

    dmarsh Terabyte Poster

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    Professional soldering rigs are temperature controlled and have current sensors to cut off excessive heat from being applied.

    Wick can be useful for removing solder.

    Specialist tips, desolder irons and hot air guns also exist for removing surface mount chips.

    Many links around on soldering, but I'd reccomend getting an electrical pro round, electronics is something that seems to take practice in my experience, wrong tools and dodgy technique, you're gonna fry the first 20 projects you attempt.

    http://www.daycounter.com/Articles/Solder-Surface-Mount-Parts.phtml
    http://www.engadget.com/2006/03/07/how-to-make-a-surface-mount-soldering-iron/
    http://sci.tech-archive.net/Archive/sci.electronics.repair/2007-06/msg00917.html

    You might have dry joints on the ports or the port controller chips might be fried, it was a common fault.

    Reseating all chips first might be worth a shot though as its pretty quick.
     
    Last edited: Jan 22, 2010
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  4. UKDarkstar
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    UKDarkstar Terabyte Poster

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    Amiga ....... drooooool ! :p

    Cut my computin' teeth on an A2000 and since then have raided Ebay and got several 500's, 1200, 3000, 4000 etc etc (you get the picture !)

    Multi-tasking before Mr Gates had ever even thought of it ! :twisted:

    Hope you get it sorted m8 !

    Perhaps your local Radio Shack knows someone that can help ?
     
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  5. dmarsh

    dmarsh Terabyte Poster

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    Last edited: Jan 22, 2010
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  6. ericrollo

    ericrollo Megabyte Poster

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    I just use one of those things which suck the solder when it is hot to remove solder. Dont know what you call it but it works for me.
     
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  7. dmarsh

    dmarsh Terabyte Poster

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    De-soldering pump ? Yeah they can be used as well.
     
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  8. BosonMichael
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    BosonMichael Yottabyte Poster

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    Ain't that the truth. I made a complete mess of the first two I tried. :blink Maybe I haven't practiced enough, but I don't seem to have a knack for it.

    In any case, I certainly don't want the Amiga to be fatality #3! :D

    Yeah, the chips that control the port are the socketed ones that I can reseat or change out easily. The soldered one (U15, the 74HC/LS157) is a bit switcher that multiplexes 8 input lines into 4. And one guy on the Amiga forums suggests that I might also have to replace a resistor that might have blown - yet more soldering.

    As you might guess, I'm hoping for the reseat/replace. I'm sure I could resell the chips if that's not the problem.
     
    Last edited: Jan 22, 2010
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    WIP: Just about everything!
  9. BosonMichael
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    BosonMichael Yottabyte Poster

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    Dude, I adored my Commodores... VIC-20, C=64, C=128, Amiga 500. Absolute brilliance.

    BosonThomas suggested that as well... but every time I've gone into a Radio Shack in the past few years, there's nothing but burnouts that barely know how to operate a cash register. :blink

    There used to be a component shop in Nashville called Javanco that had ANYTHING you could possibly want along those do-it-yourself lines... but sadly, it shut down years ago. I haven't found a suitable replacement shop yet.
     
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    WIP: Just about everything!
  10. jk2447

    jk2447 Petabyte Poster Moderator

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    Hey man you forgot the C16+4. A legend :biggrin
     
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  11. BosonMichael
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    BosonMichael Yottabyte Poster

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    Didn't forget it; I didn't have that one. :)
     
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    WIP: Just about everything!
  12. UKDarkstar
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    UKDarkstar Terabyte Poster

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    My cake on my 18th Birthday was done to resemble my VIC20 :p
     
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