Amiga 3000 VGA out not working

Zippy Zapp · 27 November 2014, 19:55

Hello,

Someone offered to sell me an Amiga 3000 but the VGA out does not work. I asked what about it does not work but have not heard back.

He said the standard Amiga video works fine.

What can cause this to not function and could it be an easy fix? Don't want to spend $400+ if it can't be fixed.

If it matters he said the floppy drive does not work. I have a few A2000 floppy drives, hoping those work.

Any thoughts? My research has been fruitless other than one old thread that talks about turning the pot to relieve garbled display.

EDIT: The previous owner said that he gets no signal from the VGA connector (31khz), if that helps. He said it was like that when he got it 5 or so years ago but that it is still a rock solid system, as long as you use the 15khz video.

Thanks!

Michael Sykes · 28 November 2014, 01:10

Never had a 3000 myself but maybe the build-in scandoubler is just dead.....

Zippy Zapp · 28 November 2014, 01:15

Yeah that could be the case too. I don't know $400 might be more than I want to spend for a 3000. One thing I thought of, looking at the motherboard, I wonder if it could be the toggle switch that you use to enable or disable. Commodore used those switched in a lot of their computers including on the 1581 drives and I had one go bad and it was stuck in the off position. Hmm...

alexh · 28 November 2014, 09:23

There is a switch at the back to select scandoubled or standard output on VGA. It must be set to scandoubled to work with modern monitor
The AMBER chip is a scandoubler, not a scan rate converter. You must be in a 60hz screen mode (i.e. NTSC) to work with most modern monitors
There is a screw next to the switch to fine tune the output. Try adjusting it?

Zippy Zapp · 28 November 2014, 09:29

Thanks for the replies.
The switch, I am told, is set to enable.
I don't know about the POT screw to adjust it or if that has been tried.
IT sounds like he tried all the normal troubleshooting so I am going to assume, as Michael stated that it could be something with the amber circuitry not working. It does look like there is some corrosion from a replaced battery. I see some signs of leaking caps too. I think Ill save my 400 quid. :-)

Franchute13 · 28 November 2014, 12:52

Hello.
1) Check the battery status. If battery acid leak perhaps the problem.
2) The Amber chip may be dead.
3) Problem with capacitors
4) Problem of some other chip like as the NE564

If you can, get a picture of the motherboard
regards

Zippy Zapp · 28 November 2014, 17:20

Thanks Franchute13.

Here is a picture of that area. I spotted a couple things near the battery. One is a capacitor that looks suspicious on the solder pad. And some other spots that look off.

Franchute13 · 28 November 2014, 18:43

Quote:

Originally Posted by Zippy Zapp

Thanks Franchute13.

Here is a picture of that area. I spotted a couple things near the battery. One is a capacitor that looks suspicious on the solder pad. And some other spots that look off.

Hello.
At first glance you need a capacitor. Watch the integrated U480 your photo and compares this photo.
http://www.bigbookofamigahardware.co...a3000rev89.jpg
Yellow capacitor (C495) is missing.
Near the capacitor is missing, there is a resistance (R469 - Brown Black Red Gold). A leg (oxidized) resistance it meets the leg 2 U477. Check continuity.
That I see in your photo.

Zippy Zapp · 28 November 2014, 19:18

Wow, good catch and comparison. That's fantastic that you caught those things and saved me $400. I'll save my money until a better A3000 comes along.

Thanks for the expert analysis and comparison photo, you saved me a lot of trouble. I am guessing since the rest of the Amiga works fine, that area must be for the Amber/Scandoubler circuit? If all those things were corrected it might work again. I just don't want to be the one to do it until my soldering skills are better.

Cheers,

Paul

Franchute13 · 28 November 2014, 20:30

Yes, this area is where the Amber / Scandoubler works.
Perhaps this document will help you understand and repair A3000.
http://www.amigawiki.de/dnl/schematics/a3000.pdf
regards

Zippy Zapp · 30 November 2014, 01:00

Thanks for the info, very helpful.

Franchute13 · 02 December 2014, 03:05

Hi!
Look at this thread. I had problem with the flicker and repair it.
http://eab.abime.net/showthread.php?t=75257&page=2

27 November 2014, 19:55	#1
Zippy Zapp Registered User Join Date: Sep 2013 Location: CA/USA Posts: 346	Amiga 3000 VGA out not working Hello, Someone offered to sell me an Amiga 3000 but the VGA out does not work. I asked what about it does not work but have not heard back. He said the standard Amiga video works fine. What can cause this to not function and could it be an easy fix? Don't want to spend $400+ if it can't be fixed. If it matters he said the floppy drive does not work. I have a few A2000 floppy drives, hoping those work. Any thoughts? My research has been fruitless other than one old thread that talks about turning the pot to relieve garbled display. EDIT: The previous owner said that he gets no signal from the VGA connector (31khz), if that helps. He said it was like that when he got it 5 or so years ago but that it is still a rock solid system, as long as you use the 15khz video. Thanks! Last edited by Zippy Zapp; 28 November 2014 at 00:53.

28 November 2014, 09:23	#4
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,448	There is a switch at the back to select scandoubled or standard output on VGA. It must be set to scandoubled to work with modern monitor The AMBER chip is a scandoubler, not a scan rate converter. You must be in a 60hz screen mode (i.e. NTSC) to work with most modern monitors There is a screw next to the switch to fine tune the output. Try adjusting it?

28 November 2014, 17:20	#7
Zippy Zapp Registered User Join Date: Sep 2013 Location: CA/USA Posts: 346	Thanks Franchute13. Here is a picture of that area. I spotted a couple things near the battery. One is a capacitor that looks suspicious on the solder pad. And some other spots that look off. Attached Thumbnails

02 December 2014, 03:05	#12
Franchute13 Registered User Join Date: Feb 2013 Location: Argentina Posts: 281	Hi! Look at this thread. I had problem with the flicker and repair it. http://eab.abime.net/showthread.php?t=75257&page=2 Last edited by Franchute13; 02 December 2014 at 04:23.

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28 November 2014, 01:10	#2
Michael Sykes WinUAE end user Join Date: Jan 2014 Location: Bremen Age: 44 Posts: 649	Never had a 3000 myself but maybe the build-in scandoubler is just dead.....

28 November 2014, 01:15	#3
Zippy Zapp Registered User Join Date: Sep 2013 Location: CA/USA Posts: 346	Yeah that could be the case too. I don't know $400 might be more than I want to spend for a 3000. One thing I thought of, looking at the motherboard, I wonder if it could be the toggle switch that you use to enable or disable. Commodore used those switched in a lot of their computers including on the 1581 drives and I had one go bad and it was stuck in the off position. Hmm...

28 November 2014, 09:29	#5
Zippy Zapp Registered User Join Date: Sep 2013 Location: CA/USA Posts: 346	Thanks for the replies. The switch, I am told, is set to enable. I don't know about the POT screw to adjust it or if that has been tried. IT sounds like he tried all the normal troubleshooting so I am going to assume, as Michael stated that it could be something with the amber circuitry not working. It does look like there is some corrosion from a replaced battery. I see some signs of leaking caps too. I think Ill save my 400 quid. :-)

28 November 2014, 12:52	#6
Franchute13 Registered User Join Date: Feb 2013 Location: Argentina Posts: 281	Hello. 1) Check the battery status. If battery acid leak perhaps the problem. 2) The Amber chip may be dead. 3) Problem with capacitors 4) Problem of some other chip like as the NE564 If you can, get a picture of the motherboard regards

28 November 2014, 19:18	#9
Zippy Zapp Registered User Join Date: Sep 2013 Location: CA/USA Posts: 346	Wow, good catch and comparison. That's fantastic that you caught those things and saved me $400. I'll save my money until a better A3000 comes along. Thanks for the expert analysis and comparison photo, you saved me a lot of trouble. I am guessing since the rest of the Amiga works fine, that area must be for the Amber/Scandoubler circuit? If all those things were corrected it might work again. I just don't want to be the one to do it until my soldering skills are better. Cheers, Paul

28 November 2014, 20:30	#10
Franchute13 Registered User Join Date: Feb 2013 Location: Argentina Posts: 281	Yes, this area is where the Amber / Scandoubler works. Perhaps this document will help you understand and repair A3000. http://www.amigawiki.de/dnl/schematics/a3000.pdf regards

30 November 2014, 01:00	#11
Zippy Zapp Registered User Join Date: Sep 2013 Location: CA/USA Posts: 346	Thanks for the info, very helpful.

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