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Old 20 November 2019, 00:15   #21
solarmon
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I'm surprised your multi-meter does not have a continuity test mode. The workaround is to use resistance/ohms measurement - but then you won't have the benefit of a buzzer.

I can't recommend anything specific about an Amiga RGB to SCART adapter, but you will probably find, as you have already noticed, that it will probably come with a 25-pin connector that has been modded to be a 23-pin one.
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Old 20 November 2019, 07:19   #22
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Quote:
Originally Posted by solarmon View Post
I can't recommend anything specific about an Amiga RGB to SCART adapter, but you will probably find, as you have already noticed, that it will probably come with a 25-pin connector that has been modded to be a 23-pin one.
http://eab.abime.net/showthread.php?t=47281
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Old 20 November 2019, 09:53   #23
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Originally Posted by solarmon View Post
I'm surprised your multi-meter does not have a continuity test mode. The workaround is to use resistance/ohms measurement - but then you won't have the benefit of a buzzer.

I can't recommend anything specific about an Amiga RGB to SCART adapter, but you will probably find, as you have already noticed, that it will probably come with a 25-pin connector that has been modded to be a 23-pin one.
Something OCD about me though that wants the right plug (23pin) as to me the 25 pin hacked to make a 23 pin is a bodge, just my OCD. I'm quite excited to try and get this Amiga working again, got plenty to do if I can get the main board working again. Keyboard and floppy drive will need a complete strip down, need to find and buy a side expansion port cover and trap door as both missing, and try and fix a broken tab on the inside of the upper case. so I have my work cut here I think, just hope I can get the board working first.

Thanks for your and other people help so far on this, much appreciated.
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Old 20 November 2019, 09:55   #24
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Thanks I've read this post, I'm trying to find a 23 female dsub connector and cover as I don't really want to use a 25 pin version.
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Old 20 November 2019, 12:09   #25
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Just wondering if the mono component output is working, is this easy to test?
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Old 20 November 2019, 14:33   #26
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You can connect the mono luminance out to your display's composite in to test it.
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Old 20 November 2019, 14:45   #27
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You can connect the mono luminance out to your display's composite in to test it.
Yes done this, but get no output, just the same black screen, no change at all. Wanted to make sure this method I'm using is working as I am only using this method for the Amiga.
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Old 21 November 2019, 12:50   #28
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Whilst I'm waiting for a RGB to Scart cable I thought I'd have a go at cleaning the case. As you can see when I got this describing it as filthy would have been understatement. I got to work with a cheap window cleaner I bought from Sainsbury, some methelated spirit to help remove the black marker filled in Amiga logo and then baking soda. Its getting there but there are still some areas with yellow marks, especially around the edges... not sure how to remove these.

Does anyone know if the Commodore "C" on this case should be surrounded by this black colour or has that been "inked in" as well? Having a quick look around the internet seems to show the embossed "C" logo is not surrounded by a dark square. If it's been added I'll try and remove the black/grey colour.

Edit: oh seen this on ebay so maybe I should try and remove the colouring, most seem to be stickers rather than embossed.

Amiga with embossed logo
Ta

Before
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Last edited by stevew; 21 November 2019 at 13:07.
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Old 23 November 2019, 14:35   #29
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RGB cable arrived this morning, really happy as comes with actual 23 pin plug rather than 25 pin cut down, it's the small things :-)

So power up the Amiga and I get a green screen straight away. so thinking this could be either CIA or chip ram.

What is the best way to clean the cia sockets and chip pins? Do I use a fibre scracth pen on the pins, if so what about the sockets?

Cheers
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Old 23 November 2019, 15:06   #30
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Great! A step forwards!

A green screen means that there is a problem with memory - either detecting it, or configuring it. Which translate to either bad signals/traces of memory address and data lines between components that they go through and to, or the memory chips themselves (because they are defective, or not getting power).

A problem with a CIA should not give a green screen from my experience. It is more likely corrosion to traces and chip legs and sockets.

So a lot of things that could go wrong and that needs to be checked!

Did you already reseated and cleaned the pins and sockets of all the socket chips?

I USB microscope is useful for inspections as things will show up that the naked eye cannot see.

Last edited by solarmon; 25 November 2019 at 20:15.
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Old 23 November 2019, 15:16   #31
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Great! A step forwards!

A green screen means that there is a problem with memory - either detecting it, or configuring it. Which translate to either bad signals/traces of memory address and data lines between components that they go through and to, or the memory chips themselves (because they are defective, or not getting power).

A problem with a CIA should give a green screen from my experience. It is more likely corrosion to traces and chip legs and sockets.

So a lot of things that could go wrong and that needs to be checked!

Did you already reseated and cleaned the pins and sockets of all the socket chips?

I USB microscope is useful for inspections as things will show up that the naked eye cannot see.
Yep cleaned the chips pins with scratch pen.

It seems if i leave the keyboard unplugged I just got a black screen, keyboard plugged in and green screen.
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Old 23 November 2019, 15:24   #32
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There may be a separate reset issue on your A500 - the keyboard is providing a reset signal in addition to the 555 timer on the motherboard. The A500 should be able to boot up without the keyboard.

But we need to fix the green screen issue first!

Looks like you'll need check the traces and pins with a multimeter. Use http://www.amigapcb.org/ and https://www.amigawiki.org/doku.php?i...chematics#a500 to help with this.
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Old 23 November 2019, 16:05   #33
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Congrats to the case cleanup stevew - it looks so much better now!

About the scratchpen:
Be careful with it. It works well, but it produces extremely small glass particles which can enter the skin and you also should not inhale. So dispose the particles safely.

About the Agnus label:
The number on Agnus is 3087 (see pic) and probably is the production datecode of week 30 in 1987.

To ease your work: Buy a multimeter (cont. check). Many years back they were pricey but now they got so incredibly cheap, you get a good one (for this task) for 20 to 40 Euro.

Good luck, seems you'r making good progress

@solarmon: Is there a usb microscope you can recommend?
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Old 23 November 2019, 16:35   #34
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Congrats to the case cleanup stevew - it looks so much better now!

About the scratchpen:
Be careful with it. It works well, but it produces extremely small glass particles which can enter the skin and you also should not inhale. So dispose the particles safely.

About the Agnus label:
The number on Agnus is 3087 (see pic) and probably is the production datecode of week 30 in 1987.

To ease your work: Buy a multimeter (cont. check). Many years back they were pricey but now they got so incredibly cheap, you get a good one (for this task) for 20 to 40 Euro.

Good luck, seems you'r making good progress

@solarmon: Is there a usb microscope you can recommend?
Thanks for your comments.

Here are few more images of how it was when I received it, and a few after after spending this morning cleaning the metal shielding.

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Old 23 November 2019, 16:36   #35
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There may be a separate reset issue on your A500 - the keyboard is providing a reset signal in addition to the 555 timer on the motherboard. The A500 should be able to boot up without the keyboard.

But we need to fix the green screen issue first!

Looks like you'll need check the traces and pins with a multimeter. Use http://www.amigapcb.org/ and https://www.amigawiki.org/doku.php?i...chematics#a500 to help with this.
Where do recommend I start? with the CIA sockets?
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Old 23 November 2019, 16:40   #36
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@solarmon: Is there a usb microscope you can recommend?
I wouldn't say I would 'recommend' it, but it is just what I have and it does a good enough job for me at the moment - one of these 1000x magnification USB microscope/endoscope style ones. They are very cheap and you gets what yous pay for. Something like:

https://www.amazon.co.uk/KKmoon-Micr...519577&sr=8-10

There are many of these from various vendors on Amazon and eBay - so shop around.
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Old 23 November 2019, 16:47   #37
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Where do recommend I start? with the CIA sockets?

I would start with reseating (with PLCC extractor, or by pushing it through from underneath through the two holes - be careful!!) and cleaning Agnus pins and sockets.

Then it is the painful task of checking all the memory address and data lines. And do it several times, because you WILL miss some! Find a methodical process that you are comfortable with to minimise missing and mis-testing the traces. Again, use http://www.amigapcb.org/ and https://www.amigawiki.org/doku.php?i...chematics#a500 to help with this.
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Old 23 November 2019, 16:52   #38
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Could you get a close up of your trapdoor expansion port, both top and bottom sides - from the picture of the bottom of the board it looks like there has been some work on it?
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Old 23 November 2019, 17:03   #39
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Could you get a close up of your trapdoor expansion port, both top and bottom sides - from the picture of the bottom of the board it looks like there has been some work on it?
Here you go. How do I test the memory address and data lines, put one tip of the multimeter on a ram chip leg and the other on...?

Will those boards help me as they are rev 6,7 and 8. Mine is a rev 5?

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Old 23 November 2019, 17:12   #40
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I would start with reseating (with PLCC extractor, or by pushing it through from underneath through the two holes - be careful!!) and cleaning Agnus pins and sockets.

Then it is the painful task of checking all the memory address and data lines. And do it several times, because you WILL miss some! Find a methodical process that you are comfortable with to minimise missing and mis-testing the traces. Again, use http://www.amigapcb.org/ and https://www.amigawiki.org/doku.php?i...chematics#a500 to help with this.
I have PLCC extractor now, what is the best way to clean this chip and socket?

Thanks
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