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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: sturulez on March 02, 2020, 09:40:56 AM
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Hi,
I turned on my Amiga 1200 yesterday and noticed something wasn't right. First thing i noticed is that when i turned it on the Amiga the power light came on but the HDD and FDD where not active, no ticking sound from the floppy drive so i thought I would change the power supply but that had no effect.
Secondly I opened up the Amiga, disconnected the accelerator and CF Card turned it on and nothing happened. I then removed the ROM 3.1 chips and replaced them with 3.0 ROM, turned on and nothing happened. I then put the 3.1 ROM's back in and the Amiga came back to life.
I noticed after I rebooted the machine a few times a green light appeared on the screen, but not every time, am I right in believing this might be a RAM issue?
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A green screen typically means trouble with chipram, yes.
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How easy is this to fix?
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How easy is this to fix?
Depends on whether the problem is in a RAM chip or on the motherboard - not hard to fix for someone with the right soldering skills and knowledge on how to find the problem. Are you capable of flashing ROM chips? Have you tried Diagrom? http://www.diagrom.com
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I've never tried flashing ROM chips or used Diagrom before
:-\
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First of all I would suggest to remove all Chips from the Sockets, clean sockets and Chips and replace the Chips.
A green screen can also be a sign of a contact-issue…. because after replacing the roms it worked again… so clean the contacts and the Chips.
or gently press on the Chips in the sockets….
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As people said.
Also is this Amiga recaped?
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No this Amiga hasn't been recapped. I purchased it from Amiga kit about 10 years ago.
Okay so this evening I took the amiga apart. I am yet to clean the chips and remove them from the sockets.
I did replace the 3.1 ROM chips with 3.0. Couldn't see an issue. I then thought I would use the 3.1 chips again. everything booted up okay into workbench. I left the amiga for about 10 minutes and when i came back the screen was green. I then turned the amiga off, back on again and the screen was dark grey with black vertical lines. No sound was coming from the floppy drive and the hard drive wasn't doing anything.
Performed a Ctrl + A + A and rebooted it, the screen flashed up purple for a few seconds and then went back to black again.
Could my 3.1 ROM chips be faulty?
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If my ROM chips are not at fault would a recap resolve the issue?
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Not sure about that but every Amiga should be recapped, especially smd models like 600/1200.
My 1200 had floppy issues, it was caused by this.
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What I would do is fully remove the motherboard from the A1200, completely. Unhitch the floppy drive and keyboard and remove any cards. And then hook up an external floppy drive and mouse and boot and count elephants until she clocked on. Then boot from floppy externally. And while your at it stick a backlight behind the mobo and take some cool pics like XRAY thro the board. Just looks cool. Then take very close up pictures of each and every capacitor for sng's and worry over them in close up on your PC.
The test out of the case with nothing attached will tell you if she is working. Get SySInfo and other test mobo floppies. Not sure I read anything about the PSU. But if you have a light brick get a heavier one. And check the PSU with it unplugged from the Amiga and listen for a low thumping noise. Don't worry wont catch on fire till it rattles very loud. Make sure your power connector hasn't worked loose.
I recently had what you had cus the floppy disk button was stuck. And also press thise switches up and down a bit on the mouth to the floppy.
Just start from the ground up and that starts at the power plug. Check wiring PSU connector stripped motherboard dry joints rear view and xray and capacitor. Its probably the floppt ribbon loose or the power switch or even a broken pillar on a key that is sending a delete signal continuously to the computer. By removing the possibility for faults you get to the problem quicker.
You didn't spill coffee on her did you... ? Retrace what you did. And don't leave heavy objects on the keyboard again... That book was way to heavy.
There is no point getting something fixed that doesn't need fixing. All that happens is that you risk breaking something else.
Have fun.. but be safe with electricity.
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Okay this evening I removed the motherboard from the outer casing. Luckily I have a spare Amiga 1200 so I’ve managed to test the ROM’s on that machine and they work fine.
The faulty board is a Rev 1A and the working board in a Rev 2B
Upon inspection of the faulty motherboard I noticed round circular component near to where the PSU plugs in looks like something might of leaked out of it. See the attached photo
When the 3.1 ROM’s and floppy drive are plugged into the faulty board nothing happens when power it up, Just presented with a blank screen now.
Am I right in believing a recap for this would possibly resolve the issue?
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Please see attached image
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That is not a capacitor :-)
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Hi
Sorry to hear of the problems.
If it is one of our boards originally then please send it in to us this week and we will put it on our bench and test it. We will advise the best course of repair action after inspection.
Thanks
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Please see attached image
It's a ferrite bead used to supress RF interference. It looks like some kind of resin that was applied at the factory in a rather slap dash fashion. Some board don't appear to have any resion applied but I found this example on BBOH.
https://www.bigbookofamigahardware.com/bboah/media/download_photos/a1200mb_rev1d4_power_darkgreen.jpg
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Hi!
A recap won't fix the issue unless there has been major leakage but does not really affect the A1200 in this way. It maybe Gayle or simply clean up the expansion connector. Careful removing ROMS as you could damage the tracks under the ROM.
Good luck!
Steve
Not sure about that but every Amiga should be recapped, especially smd models like 600/1200.
My 1200 had floppy issues, it was caused by this.
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I have a feeling it might be the tracks under the ROM, they have had various ROM's in there over the last few days. :-\
Certainly not the easiest chip to get out if you have taken the heat shield off.
Hi!
A recap won't fix the issue unless there has been major leakage but does not really affect the A1200 in this way. It maybe Gayle or simply clean up the expansion connector. Careful removing ROMS as you could damage the tracks under the ROM.
Good luck!
Steve
Not sure about that but every Amiga should be recapped, especially smd models like 600/1200.
My 1200 had floppy issues, it was caused by this.
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Many Thanks to Amigakit for sorting out my A1200.
All working now :)
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Great!
What was the problem?
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Power caps leakage, full recap and replaced 4 x RAM chips
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The new AmigaKit's FAST! ;D