RGB Scart on A1200 totally black

Megatron-UK · 06 April 2010, 20:34

I've recently moved house and have been setting up my dedicated games room, one of the systems I've set up is my old A1200. The last time I used it was around 18 months ago, when it was working fine.

In terms of video hardware it's standard, using a 23way to scart cable I've used for years.... however I'm now not getting any picture at all, just a black screen - while the Amiga continues to hunt for a floppy and then boot to workbench... well, I say just a black screen, but if I turn the brightness all the way to maximum I can just about make out the outlines of desktop icons and workbench bar - in desperation I disconnected everything - CF disk drive, 030 accelerator, even the mouse, instead I now just barely make out the shape of the disk-insert animation of the kickstart screen.

This is happening on *every* TV I've tried; very old 14" portables, a 15 year old 20" Mitsubishi that plays every single console I've hooked up to it, several newish LCD screens and a brand new Panasonic plasma display. All of which have had no trouble with this system on scart in the past. I've also used two known-good 23-way to scart cables, both with the same issue.

Help! Has anyone else come across this problem? I've taken a look at the pcb and cannot see any obvious signs of damage, shorting or corrosion.

John

alexh · 06 April 2010, 20:40

Your SCART cable might have resistors on the R, G, B wires. Other home computers such as the Spectrum +3 and Amstrad needed them but the Amiga does not. Can you ever remember this particular SCART cable ever working with any of these TV's?

Should only take a few minutes to check.

http://eab.abime.net/showpost.php?p=592491&postcount=1

Megatron-UK · 06 April 2010, 20:47

Neither cable has resistors on the r/g/b lines - they're straight through. They've both definitely worked before on the Mitsubishi crt, an old Microvitec Cub and several of my newer LCD tv's before it got packed away just under 2 years ago.

I thought it might have been the display settings from when I last used it on the LCD tv, I remember tweaking the monitor settings it to get the best refresh and overscan that was possible via the scart connection - that's why I also tried with the disk unplugged; but it seems more fundamental than that, as even the kickstart screen has the same issue.

alexh · 06 April 2010, 20:49

You tried an RF cable to the TV aerial?

That would confirm if it truly was fundamental or something to do with the cable / 23-pin plug.

Megatron-UK · 06 April 2010, 20:56

Sorry, yes, I should have said that. I *do* get a correct image via the composite jack.

Djay · 07 April 2010, 01:56

might be worth speaking with amigakit.com (they post here), they would probably be able to fix it (Analogue RGB video out DB-23M)... or buy a A1200 from ebay

rkauer · 07 April 2010, 05:10

Chances are the cable was disconnected while the Amiga was on.

In such a case you must check the internal SMD resistors right on the back of the RGB port.

SailorSat · 07 April 2010, 06:59

Sounds like there is no power on the cable and your screen thinks it is a composite image (this will lead to only dim outlines of pretty much everything)

Pin 16 on the SCART should be around 3V-5V.

While not every TV needs it, most do.

Megatron-UK · 07 April 2010, 09:50

I'll probably look at picking up another A1200 then, thanks.

alexh · 07 April 2010, 10:21

I'd look at getting a new cable first, or trying the one you have on a mates Amiga.

Megatron-UK · 07 April 2010, 10:49

I seem to remember an A500+ somewhere in my parents attic.... I'll see if it's still there this weekend - none of my mates are into older systems, so that's the only other option.

Megatron-UK · 07 April 2010, 20:44

Found the A500 this evening - I don't know why I kept it, as the keyboard doesn't work.... but it powers up fine and the kickstart logo is crystal clear on both of the db23<->scart cables I tried the A1200 with.

Looks like either I've fried the A1200 RGB output somehow, or it has died while in storage. Guess I'll have to look for another one

At least I can swap all of the upgrades across.

alexh · 07 April 2010, 20:58

If it is an A500+ then the keyboard problems are probably due to battery leakage. You could probably fix it in a few minutes. Even in poor condition the A500 is still worth something. If you have a full A501+ 1Mbyte RAM upgrade in your A500+ and a working floppy drive you could probably sell them for the price of an A1200 motherboard. The key-caps, case and trapdoor cover might be worth something if they are not too yellow.

If you are resigned to buying another A1200 motherboard and you have access to a multimeter and soldering iron why not have a go at fixing it? Members on this forum would walk you through it.

Megatron-UK · 07 April 2010, 21:10

They're very yellow

(from my online database of all my gaming items)

I'll put the A500 on the list of 'things to do'... I should probably try to sort it as it's in great condition other than the yellow case and keyboard problem.

I'm actually reasonable with a soldering iron... I guess I can give it a go; any ideas where I should start? I've got the motherboard removed.

alexh · 07 April 2010, 21:13

You sure it is an A500 plus? That doesn't look like one.

If that is the wrong photo, and it is an A500+ then get that battery out ASAP. The longer it is in the more damage is being done. It will take no more than 30 mins to an hour to get it out.

http://eab.abime.net/showthread.php?t=47185

Megatron-UK · 07 April 2010, 21:22

I could be wrong... I haven't used an A500 since I was 15 or 16 (this one was a freebie from a family friend 3-4 years ago and I powered it up, tested it worked and put it straight in the attic), so that's probably a good 16 years or so ago.

It has a ram expansion/battery backed clock in the trapdoor:
http://targetearth.dyndns.org/vgdb_a...ry/bysystem/16

edit: actually, looking back the images I took of it when I added it to my inventory, it's clearly an A500 by the sticker on the bottom of the case... doh

rkauer · 08 April 2010, 04:45

You mentioned a bit of "fur" in the battery: that's leakage!

Remove the battery in a hurry, before it destroys the RAM expansion.

Megatron-UK · 08 April 2010, 10:10

I did clean it off with some acetone after I took the pictures... it seemed fine after that.

fitzsteve · 08 April 2010, 10:25

Quote:

Originally Posted by Megatron-UK

I did clean it off with some acetone after I took the pictures... it seemed fine after that.

As rkauer says get that battery out of there ASAP or else it will kill your Miggy...

Also, if you really want a working Battery, Amigakit sell replacements.

I've lost a Ram expansion due to leakage on my A1200

rkauer · 08 April 2010, 18:49

@Fitzsteve: worst than you, I lost an A1200 accelerator!

OK, was not a terrible thing: was an Apollo 1220 and the rechargeable battery blew up, taking the board with it.

06 April 2010, 20:34	#1
Megatron-UK Registered User Join Date: Aug 2009 Location: UK Posts: 30	RGB Scart on A1200 totally black I've recently moved house and have been setting up my dedicated games room, one of the systems I've set up is my old A1200. The last time I used it was around 18 months ago, when it was working fine. In terms of video hardware it's standard, using a 23way to scart cable I've used for years.... however I'm now not getting any picture at all, just a black screen - while the Amiga continues to hunt for a floppy and then boot to workbench... well, I say just a black screen, but if I turn the brightness all the way to maximum I can just about make out the outlines of desktop icons and workbench bar - in desperation I disconnected everything - CF disk drive, 030 accelerator, even the mouse, instead I now just barely make out the shape of the disk-insert animation of the kickstart screen. This is happening on every TV I've tried; very old 14" portables, a 15 year old 20" Mitsubishi that plays every single console I've hooked up to it, several newish LCD screens and a brand new Panasonic plasma display. All of which have had no trouble with this system on scart in the past. I've also used two known-good 23-way to scart cables, both with the same issue. Help! Has anyone else come across this problem? I've taken a look at the pcb and cannot see any obvious signs of damage, shorting or corrosion. John

07 April 2010, 21:22	#16
Megatron-UK Registered User Join Date: Aug 2009 Location: UK Posts: 30	I could be wrong... I haven't used an A500 since I was 15 or 16 (this one was a freebie from a family friend 3-4 years ago and I powered it up, tested it worked and put it straight in the attic), so that's probably a good 16 years or so ago. It has a ram expansion/battery backed clock in the trapdoor: http://targetearth.dyndns.org/vgdb_a...ry/bysystem/16 edit: actually, looking back the images I took of it when I added it to my inventory, it's clearly an A500 by the sticker on the bottom of the case... doh Last edited by Megatron-UK; 07 April 2010 at 21:33.

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06 April 2010, 20:40	#2
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,470	Your SCART cable might have resistors on the R, G, B wires. Other home computers such as the Spectrum +3 and Amstrad needed them but the Amiga does not. Can you ever remember this particular SCART cable ever working with any of these TV's? Should only take a few minutes to check. http://eab.abime.net/showpost.php?p=592491&postcount=1

06 April 2010, 20:47	#3
Megatron-UK Registered User Join Date: Aug 2009 Location: UK Posts: 30	Neither cable has resistors on the r/g/b lines - they're straight through. They've both definitely worked before on the Mitsubishi crt, an old Microvitec Cub and several of my newer LCD tv's before it got packed away just under 2 years ago. I thought it might have been the display settings from when I last used it on the LCD tv, I remember tweaking the monitor settings it to get the best refresh and overscan that was possible via the scart connection - that's why I also tried with the disk unplugged; but it seems more fundamental than that, as even the kickstart screen has the same issue.

06 April 2010, 20:49	#4
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,470	You tried an RF cable to the TV aerial? That would confirm if it truly was fundamental or something to do with the cable / 23-pin plug.

06 April 2010, 20:56	#5
Megatron-UK Registered User Join Date: Aug 2009 Location: UK Posts: 30	Sorry, yes, I should have said that. I do get a correct image via the composite jack.

07 April 2010, 01:56	#6
Djay 95th User Join Date: May 2001 Location: Brighton/UK Age: 48 Posts: 3,120	might be worth speaking with amigakit.com (they post here), they would probably be able to fix it (Analogue RGB video out DB-23M)... or buy a A1200 from ebay

07 April 2010, 05:10	#7
rkauer I hate potatos and shirts Join Date: Oct 2007 Location: Sao Leopoldo / Brazil Age: 58 Posts: 3,482	Chances are the cable was disconnected while the Amiga was on. In such a case you must check the internal SMD resistors right on the back of the RGB port.

07 April 2010, 06:59	#8
SailorSat Registered User Join Date: Jun 2009 Location: Hanau / Germany Age: 41 Posts: 65	Sounds like there is no power on the cable and your screen thinks it is a composite image (this will lead to only dim outlines of pretty much everything) Pin 16 on the SCART should be around 3V-5V. While not every TV needs it, most do.

07 April 2010, 09:50	#9
Megatron-UK Registered User Join Date: Aug 2009 Location: UK Posts: 30	I'll probably look at picking up another A1200 then, thanks.

07 April 2010, 10:21	#10
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,470	I'd look at getting a new cable first, or trying the one you have on a mates Amiga.

07 April 2010, 10:49	#11
Megatron-UK Registered User Join Date: Aug 2009 Location: UK Posts: 30	I seem to remember an A500+ somewhere in my parents attic.... I'll see if it's still there this weekend - none of my mates are into older systems, so that's the only other option.

07 April 2010, 20:44	#12
Megatron-UK Registered User Join Date: Aug 2009 Location: UK Posts: 30	Found the A500 this evening - I don't know why I kept it, as the keyboard doesn't work.... but it powers up fine and the kickstart logo is crystal clear on both of the db23<->scart cables I tried the A1200 with. Looks like either I've fried the A1200 RGB output somehow, or it has died while in storage. Guess I'll have to look for another one At least I can swap all of the upgrades across.

07 April 2010, 20:58	#13
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,470	If it is an A500+ then the keyboard problems are probably due to battery leakage. You could probably fix it in a few minutes. Even in poor condition the A500 is still worth something. If you have a full A501+ 1Mbyte RAM upgrade in your A500+ and a working floppy drive you could probably sell them for the price of an A1200 motherboard. The key-caps, case and trapdoor cover might be worth something if they are not too yellow. If you are resigned to buying another A1200 motherboard and you have access to a multimeter and soldering iron why not have a go at fixing it? Members on this forum would walk you through it.

07 April 2010, 21:10	#14
Megatron-UK Registered User Join Date: Aug 2009 Location: UK Posts: 30	They're very yellow (from my online database of all my gaming items) I'll put the A500 on the list of 'things to do'... I should probably try to sort it as it's in great condition other than the yellow case and keyboard problem. I'm actually reasonable with a soldering iron... I guess I can give it a go; any ideas where I should start? I've got the motherboard removed.

07 April 2010, 21:13	#15
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,470	You sure it is an A500 plus? That doesn't look like one. If that is the wrong photo, and it is an A500+ then get that battery out ASAP. The longer it is in the more damage is being done. It will take no more than 30 mins to an hour to get it out. http://eab.abime.net/showthread.php?t=47185

08 April 2010, 04:45	#17
rkauer I hate potatos and shirts Join Date: Oct 2007 Location: Sao Leopoldo / Brazil Age: 58 Posts: 3,482	You mentioned a bit of "fur" in the battery: that's leakage! Remove the battery in a hurry, before it destroys the RAM expansion.

08 April 2010, 10:10	#18
Megatron-UK Registered User Join Date: Aug 2009 Location: UK Posts: 30	I did clean it off with some acetone after I took the pictures... it seemed fine after that.

08 April 2010, 18:49	#20
rkauer I hate potatos and shirts Join Date: Oct 2007 Location: Sao Leopoldo / Brazil Age: 58 Posts: 3,482	@Fitzsteve: worst than you, I lost an A1200 accelerator! OK, was not a terrible thing: was an Apollo 1220 and the rechargeable battery blew up, taking the board with it.

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