Why revive this thread again.
Not going down this rabbit hole again.

The following articles have been added to the website of the Amiga magazine Obligement (http://obligement.free.fr) during the last two months:

- News for March/April 2024.
- Old articles from Generation 4 13 to 15: File: Lovecraft, Review of Chessmaster 2100, Review of 89 La Révolution Française, Review of Rick Dangerous, Review of Black Magic, Interview with Doug Glen, Interview with Jean Baudlot, Interview with Gary Gygax, File: Lucasfilm, cinema and video games, Review of 3D Pool, Review of Wind Surf Willy, etc.
- Interview with Camilla Boeman (AmigaOS 68k developer).
- Interview with Frédéric Autechaud (former editor of ANews).
- Review of AmiFox 0.3 to 0.6.
- Review of Simple Transfer.
- Review of Amiga Boot Selector 0.4.
- Review of IBrowse 3.0a.
- The best of Byte from October to December 1986.
- File: The Amiga in TV and movies (update).
- File: Utilities included in MorphOS.
- File: A history of software piracy in Italy (1983-1993).
- DIY: Restoring an Amiga 2500UX.
- Tutorial: Quick start guide for new A1222 users (update).
- Tutorial: Configuration of RoadShow 1.14/1.15 for a Freebox Revolution.
- Point of view: Rave development (part 7).
- Programming: Animating an image in C and SDL2 on MorphOS.
- Special quiz about Dave Haynie.

Rendez-vous on http://obligement.free.fr for this nice reading.
Our X page: https://twitter.com/obligement
Feel free to contribute. Please contact David "Daff" Brunet for more info.

OS 4.1

Truly,
Robert Bernardo
Fresno Commodore User Group - http://www.dickestel.com/fcug.htm
Southern California Commodore & Amiga Network - http://www.portcommodore.com/sccan
June 22-23 Pacific Commodore Expo NW 2024 - http://www.portcommodore.com/pacommex

@SpeedGeek This is from the original admin/mod discussion on the subject

He asked for help to recover his account, which we did. After regaining access, he emailed again asking if we could merge his two accounts. We replied that you are not allowed two accounts and banned the second account and gave him warning points for breaking the rules. He replied saying I was "mean" and "bye bye amibay".

1. He did NOT contact us about losing access to his original account before creating a new one.
2. We did not know he had a second account until he ADMITTED IT.
3. We carried out the appropriate actions (banned second account, issued warning points).
4. Normal, well adjusted members at that point would of apologised.

As you can see from the above HE asked for his account to be closed and we obliged.

I measured the voltage coming out of these two, and its showing 3.9v, which seems way above the 1.5 - 2.5v your sheet indicates is correct.

It's probably OK, I would have noted those values while working on some working systems, and it's likely there will be some variation between different machines.  If you see the datasheet you referenced, you'll see the voltage on COMP is a function of the reference voltage and the 'full scale adjust' input.

And you'll see it is saying the outputs are in the 20-30mV range...

I'm curious about how you're measuring the RGB output signal.  It's a complex waveform (see page 7 of your referenced datasheet), not a static DC voltage.  It's also important to note that the RGB outputs of the DAC are current sources (see the explanation on page 8), meaning that the voltages observed will depend on the impedance presented to the RGB outputs.  What that means is that unless the monitor with your SCART cable terminates each of these three signals with 75 Ohms, the voltage won't be correct, which could explain your issue.

As a point of reference, I've measured one of the RGB outputs of an A500 at the 23-way connector, with the signal driving a 1084S test monitor, correctly displaying the RGB colour bars test screen on Amiga Test Kit at the normal/correct intensity.  A correctly working A4000 will show the same waveform.  See attached, which shows three complete horizontal lines.  Given the large proportion of the white level, the three lines shown likely correspond to the horizontal white bars displayed on the test image.  The scope is showing 500mV/division.  You'll note the 'blank level' is at 500mV, while the full scale 'white level' is around 1.6V, or 600mV above the 'blank level'.


This might be a good time to check the unknowns around your SCART cable if there's any doubt with that, else you may be going down the rabbit hole of fixing something that isn't broken.  Another idea is to connect the A4000 to a known good RGB test monitor such as a 1084S using the standard RGB cable, which will isolate your issue to the A4000, or to your monitor/cable.