The red screen boot of the Jaguar usually means it cannot read the game. However there are many hardware faults that can cause this failure to boot.

Below are a few common culprits (other than actually have a bad game/dirty game slot) that can cause various red screen issues.

Most of the time it is the top row of RAM and Buffers below the cartridge connector, and it obviously could be many things, but below is a good list of typical/more common culprits to errors.

NOTE: It is super useful to have a Game Drive when diagnosing as it allows for further granularity in testing as you will see below.

Thanks to Crossface Gaming and RetroHQ for assisting with this information also.

If you get a glitchy red screen then it is very likely RAM.



If you have a Game Drive then you should probably see a Menu Error! to further confirm it.



If you see this issue, or the Game Drive not even loading at all, start by investigating the acutal cartridge first, then U14.

Check it out in action here https://www.tiktok.com/@crossfacegaming/video/7243190174975315243?_r=1&_t=8d3tUAU7gju

Many things can cause instant red screen boot including:

Because the BIOS shares the lower expansion address pins, it is very uncommon to have bad lower address pin buffers and still get to red screen, as the BIOS would fail to load.

Because the BIOS shares the lower expansion data pins, it cannot be bad lower data pins otherwise the BIOS would not successfully load in order to show the red screen.

However if just pin EA15 or EA16 are faulty for example, you could get to red screen but with no audio (EA16) or a jumbled logo (EA15).

A delayed red screen where the console comes on but takes longer to red screen. By delayed I mean you see the Jaguar text in red with black background for a short period before it turns all red, instead of instantly turning red as the Jaguar text appears.

Many things can cause delayed red screen boot including:

Something that would be a common issue is if you replace your capacitors on the Atari Jaguar with capacitors kits from eBay or Console 5 for example, who's kits have been confirmed to be wrong.

In short, the C147 and C150 capacitors are very important to be low ESR. If they are not, they introduce significant ripple on the 5V rail.

This often results in a very strange behaviour such as random game crashes, glitched graphics, and most notably seems to cause the delayed red light boot as EA19+ pins fail to read.

This is likely due to EA19 being the furthest away from the power supply so the added noise from the wrong capacitors starts to take effect around there.

Make sure to use our capacitors or those you can trust.

I have observed and tested this using a logic analyser and found that the expansion address pins that are driven by Tom/Jerry through the expansion address buffers (U30, U31, U14).

These address pins tell the game which data to read (from which address).

As the lower address pins that are shared with the BIOS (A0 to A16), if they are faulty, you will not make it to boot screen, as the BIOS would fail to load (with the exception of a single A15 or A16 pin fault, which would cause no audio, or jumbled Jaguar logo).

So a delay red boot is only possible if the higher expansion address pins (EA15 to EA23, most typically EA17 to EA20) are bad. This can be caused by:

If EA15 is bad, you will have delayed boot and a jumbled Jaguar logo.

If EA16 is bad, you will have a delayed boot and no audio.

If EA7-20 are bad, you will have a delayed boot.

NOTE: Using Cybermorph as an example game, it does not use EA21, 22 or 23, so if those pins were pad it would still load Cybermorph.

If using a game that uses EA21-23 and they are bad, you will have a delayed boot.

If you have a bad U12 (74AC244 Buffer), because it interfaces with Jerry on the IO Read/Write and Interrupt pins that are used to control reading/writing from the expansion slot (game slot), it can cause delayed red screen.