There are some significant differences which need to be addressed between the Rev 3 and previous boards. A few of these are:
The board on the right was soldered down using solder paste and hot air.
The Rev 3 board requires a rework wire to allow the Pi to program the CPLD in-system. See the Errata section below for details.
The photo on the right shows a board with all three buttons mounted.
Next you should decide where to mount the Raspberry Pi to the Amiga Video to Pi HDMI board.
You should base this decision on whether you want the Pi's mini-HDMI connector or a full size HDMI connector exposed at the rear of the Amiga. If you want the Pi's mini-HDMI connector exposed at the rear of the Amiga (as seen on the left), this will greatly simplify the remaining work. You just need to mount the female 2x20 pin header in the far right position, as seen on the right.
If you instead want a full size HDMI connector exposed at the rear of the Amiga, such as what you see on the left, then you need to mount the female 2x20 pin header in the far left position. The photo on the right shows this.
This configuration involves more components and work, as you will need to solder down two HDMI connectors (a male at the top of the board and a female facing the rear). You will also need a left angle mini-HDMI male to full size female cable.
There is another choice, and that is if you happen to have a Pi with the header mounted on the bottom side of the board [The particular Pi in the photo actually has long pins exposed on both sides of the board].
This is what the middle (and only the middle) connector may be used for. You can mount a Pi face-up instead of face-down. Be aware that the Pi microSD card, for all Rev 3 mounting options, must face away from the card edge. This is a requirement. You can damage your Raspberry Pi and possibly your Amiga if you plug the Pi in upside-down.
The board on the right has two Pi connectors installed. You can either mount the Pi Zero face-down (using the left connector), or face-up (using the middle connector).
Once you figure out where you want to install the 2x20 pin female header, the actual installation is not too difficult. Insert the header into the desired position and use a piece of tape or tack putty to hold it in place. Flip the board over and solder one pin at an end. Press on the PCB and re-heat the pin to ensure the header is flush to the PCB. Do the same with a pin on the opposite corner of the header. Inspect to be sure the header is flush to the PCB. Now, solder all remaining pins of the header.
If you decided on an option which uses the full-size HDMI female connector at the rear of the computer, you will want to install the male and female HDMI connectors next. The female connector is a challenge to get aligned correctly on the pads. You may find, as I did, that you will need to bend out the two shield pins on one side of the connector so that the pads line up when the connector is placed on the board.
To get a good solder bond between the connector and the PCB, you may want to apply solder paste to the pads at this point.
Once you get the desired alignment of the pads, solder down one of the shield pins to hold the connector in place and inspect to verify the pads are still aligned. Now solder down the remaining shield pins using either hot air or a pencil tip soldering iron. Be careful not to touch the plastic of the HDMI connector with your soldering iron; it will melt.
The HDMI connector pads are very fine pitch. I recommend using a microscope or a strong magnifier while soldering the pads. Inspect thoroughly for shorts or poor solder junctions.
Next solder down the male HDMI connector to the top of the board. There is an odd number of pads on one side of the board and even number on the other. So long as the pins of the connector line up with all the pads, you can be confident that you've placed the connector with the correct orientation.
I recommend using solder paste, as with the female connector. Apply the solder paste before inserting the male HDMI connector in position. Solder down one shield pin and verify the pads are still aligned. Then solder down the other shield pin and both shield pins to the other side of the PCB.
Finally solder down the signal pins using either hot air or a pencil tip soldering iron. Be aware that unlike the female connector, you need to solder pins down on both sides of the PCB.
As stated above, you will want a left-angle mini-HDMI male to full-size HDMI female cable. You likely can find these on Amazon or eBay.
You may need to trim away part of the plastic shroud of the female connector. A razor blade can be used for this.
The need for trimming was due to an oversight in placement of the pads for the male HDMI connector on the card. It's too close to the button.
This problem will be corrected in the next version of the board.
Don't forget to get a 2x20 pin male header with your Raspberry Pi. Amazon eBay
The installed microSD card should have the RGBtoHDMI software, which you can find here: https://github.com/hoglet67/RGBtoHDMI/releases
The first time you start up your Amiga with the Amiga video to Pi HDMI board installed, you will need to program the CPLD. You can do this using software on the Raspberry Pi. After the Raspberry Pi has booted (just a few seconds), press the top button. The on-screen menu should appear. Use the middle button to move the cursor (arrows) down to the CPLD Recovery Menu. Press the top button to enter the CPLD Recovery Menu. Press the middle button until you reach the latest 6-12_BIT_RGB_CPLD_vXX firmware version, then press the top button to select it. Press the top button a second time to confirm, and the CPLD will be programmed. After this, you may need to power cycle your Amiga for the CPLD to begin using the new firmware. You should then see the Amiga's screen on the HDMI output of the Raspberry Pi.
If your Amiga video output from the Pi is unstable at this point, you should check that the correct Profile and Sub-Profile are set. Press the top menu button to enter the Main Menu. Press the middle button until you reach the Profile. In the case of my 60MHz NTSC Amiga 2000 and Amiga 3000, I found that Amiga 2000 works best for the Profile. You should also set the Sub-Profile. For the same Amiga, I found that Amiga 2000 60Hz is the best Sub-Profile for NTSC Amigas. After you find a profile which gives good video, be sure to use the Save Configuration menu option to save it so that your Pi will use it from cold power-on.
You can test whether the save was successful by rebooting the Pi. Go to the Information menu and select Reboot. Once the profile is configured, you should see good video sync, but there might be observable sparkle. This can be eliminated by fine tuning the sampling phase. Go to the Sampling menu and change the Sampling Phase value until no more sparkle is visible. In my Amigas, a number of 4 or 5 seems to work pretty well for the Sampling Phase.
Please check out LinuxJedi's excellent Github repository for his CPLD version of AmigaRGBtoHDMI. Most of the CPLD programming and software installation instructions are directly applicable to this board.
The Rev3 board requires a bodge wire to be installed for the Raspberry Pi to program the CPLD in-system. This bodge wire should connect pin 24 (TDO) of the CPLD to the right pad of R2.
The angle of the photo makes it a bit difficult to see where pin 24 is. It's the second pin down on the left side of the CPLD in the orientation shown.