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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: odious on January 17, 2006, 11:53:22 AM
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Hi,
I recently got given an A600 and everything was running fine untill i saw the image flicker and flash at the tv for a few seconds. After that, the image the amiga outputs is pink wether i connect it to the rf output or the composite output.
I can still distiguish windows, icons, some text but not all.
Are there any hw techy guys around to give me some help on this? I can get my hands on a soldering iron if that is of some use.
Regards,
Odious
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If the output is the same from the RF and composite, then my guess would be that one of the colour tubes in the TV you're using has gone.
Try connecting something else to the TV to check this.
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moto
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Tubes? I think there is only one tube per TV!
I think you mean electron Guns / deflectors ;)
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Whatever :-)
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moto
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Hi again.
Thanks for the replies!
I have it connected to a brand new tv set(by rf and composite) and also to a monitor i used to connect my spectrum. And in all cases, the image is pinkish. Unfortunatelly the malfunction is on amiga's side. I took a peek at the video schematics but im not much into electronics.
Hope its not a major malfunction.
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monitor for spectrum an rgb? if not try that the composit and rf on 600 comes from the same box inside the amiga if the vid signal from the chips isnt getting there correctly it might be to the amiga video output
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@odious
There me be nothing wrong with your Amiga at All! its probably just that the preferences was set to a Pink Background color.
Just go to Prefs Palette and change it to default. it should turn grey. and save it. or try different colors. but anyway.just mess around with the Pallette prefs in your Workbench/Prefs drawer.
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I guess this is the case with all kinds of software/games??
I see that some people suggested that it could be the colour preferences, but this cannot explain it if it happens with games and so on.
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Nope, if it happens with games, and the early start-up screen (your best indication as no preferences can be applied at that stage) it's a problem with one of the RGB components, in this case, green. To be sure, open an image containing something you know to be green, and it should appear very dark, pure green being shown as black. When green's missing from a neutral colour such as white or grey, the result will always be pink as they are complimentary colours.
If you have the schematics, try tracing the green line back as far as you can and check for breaks in tracks etc., especially around chip connections, but without an oscilliscope your fairly limited as to how far you can test the video circuits. With a bit of luck there'll be a broken or shorted track somewhere on the green circuit, and rectifying this will fix it... If you're unlucky, you'll need to replace some parts - not a nice job on a 600 I'm afraid...
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Hi,
Well, in fact its the green color that has a problem. This happens in games, wb, and in different tv sets. At the pallete prefs, moving the green slider has no effect whatsoever on the image. No doubt that is on the amiga side. Ill grab some schematics and follow the green line and hope it is not any major deal.
Thanks for the infos.
Regards
Odious
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Yep, that's a sure-fire way of finding out, dunno why I didn't think of it :-( I'll try dig up some schematics at home and have a look, see if I can send you on the relevant ones..
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Though, you'll really need access to an oscilliscope to trace things if it's not an obvious break...
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Hi,
I grabbed the video schematics of the 600 and started following the green line. Went excluding parts and changing resistors and condensors from the other lines (Red and blue) with the green one. After some component swapping, i swapped q212 with q211 and hit the jackpot. Now there is green color but no Red.
The faulty transistor is located behind a capacitor thats behind the composite jack. Its a 2N3904 smd.
Hope that this experience is of some use for anybody having a similar problem.
Thanks for all the tips and info, folks. Thanks Daedalus and Kthunder for giving me a start-point.
Regards,
Odious
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You could buy a new motherboard of ebay.. i know ive picked one up for £5.
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Hi,
The amiga is now fixed and running 100%.
There are great deals on ebay, but postage to Portugal sometimes can be prohibitive (i have been through that).
regards,
Odious
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happy to hear that you fixed it :-)
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Could you post a picture of your repair job?
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Hi,
Sure.
http://pwp.netcabo.pt/aquanaut/transistor1.jpg
http://pwp.netcabo.pt/aquanaut/transistor2.jpg
Cheers,
Odious
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@odious
I've repaired a number of A600s for pretty much the same problem over the last few months.
It appeared to be the leaking SMD electrolytics had caused or contributed to the buffer transistor damage.
I'd suggest replacing C324 and C334 to prevent ongoing problems. Likewise, C303 & C304 (also 22µF) tend to leak and cause audio problems.
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@Odious
Well done, that's what I call proper fixing stuff, sadly a dying art, and knowing how to replace a surface mount with an equivalent discreet transistor - nice one, and a neat and tidy job at that - Respect earned :-)
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Just looked at the pictures, I see what you mean :-)
Don't suppose you want some of the correct SMD replacements?
Have to be very careful with the board, as if the leaded device is disturbed, it can easily pull the pads and tracks off the PCB.
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Hi,
Thanks, Amigaoneproductions and Castellen.
I would be more restfull if it was a smd replacement but i couldn't find any at the city. The way it is forces me to be more carefull (even more)with the miggy. About the capacitors, ill surely replace them to assure for some time this won't happen again. I'd like to have a few of these smd transistors, how can that be arranged?
Cheers,
Odious
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Just send me your address, I'm sure I can sort something out.
I've got new SMD capacitors if you need some, but as I buy them in small quantites (50-100) it means I have to pay a fair bit for them. So you can have some transistors for free, but you might have to send me some $ for capacitors if you can't get them locally.
I've written some notes (http://amiga.serveftp.net/Replace_capacitor.html) on replacing SMD electrolytics if you need more info.