Our Amiga 500 project

[Planetinfinity]

Originally Posted by Daedalus

Do you mean the Caps Lock LED is constantly on? If so, try booting the machine without the keyboard connected. Keyboard errors can cause the rest of the machine to not boot, and a keyboard isn't required for it to boot.

No, I meant the red power led. The Caps Lock LED is working without problems.

Without a disk in the drive, booting to the insert disk screen is typically a matter of seconds. With a faulty drive or no drive, that can take longer but still less than 30 seconds.

Currently no drive is connected right now, but we waited 5 minutes.

I would agree that Kickstart 2.04 isn't the best choice. If the machine is just to play games, 1.2 or 1.3 will give the best compatibility, and if you're going to sacrifice that compatibility for user experience with the OS, 3.1 offers similar compatibility to 2.04 but makes many more improvements without requiring the extra RAM of 3.2. Ultimately though, if OS use is the way you're going, some extra RAM would be a good thing anyway, in which case 3.2(.1) is as up-to-date as you can get.

But Kickstart 2.04 should at least show the kickstart screen.

[Planetinfinity]

Originally Posted by indigolemon

I would carefully remove and re-seat the reset of the DIP chips, checking the legs for corrosion.

Beyond that, a DiagROM might be your next choice to aid you in troubleshooting the issue.

We cleaned every chip on the mainboard by removing it and clean it with alcohol and a thoothbrush. What does a DiagROM do and where do I find such a ROM ?

[indigolemon]

This should explain what Diagrom is: https://www.diagrom.com/index.php/20...at-is-diagrom/

You can find them on eBay, or someone local might be able to create on for you?

[Daedalus]

Originally Posted by Planetinfinity

No, I meant the red power led. The Caps Lock LED is working without problems.

Ah, cool. Does it keep working no matter how many times you press it, or does it stop working after, say, 9 or 10 times? If it stops working, it shows there's a pretty fundamental issue and either the CPU isn't running or interrupts aren't working.

But Kickstart 2.04 should at least show the kickstart screen.

Indeed, they all should. It was just to counter the suggestion further up to upgrade to 2.04.

[8bitbubsy]

Chip U15 has clearly been unsoldered and removed. It's located below the audio RCA connectors.
Not sure if it's required for seeing a picture, it's connected to the mouse and joystick ports.

[Planetinfinity]

Originally Posted by 8bitbubsy

Chip U15 has clearly been unsoldered and removed. It's located below the audio RCA connectors.
Not sure if it's required for seeing a picture, it's connected to the mouse and joystick ports.

Your eyes are really good, I didn't find the missing chip for minutes even you told me how I could find it.

Do you know what it this for a chip and do you know if it is possible to buy one without buying a whole mainboard ?

[8bitbubsy]

It's a 74LS157N chip (16DIP package). A common and compatible part name that is readily available for buying is SN74LS157N.
Just google it and you will find several online store that sell them. Just make sure you get the 16DIP (aka. DIP-16) version of the chip.

According to the schematics image I attached, it looks to me like the system should be able to work without this chip, but you will get severe issues with mouse/joystick input. In other words, your black screen most likely comes from something else.

[Photon]

Edit: Missed changed information on page 2...

Rev 6A is one of the most compatible, and using it with Kickstart 1.3 will run the largest percentage of games and programs from the A500 era. Only if you intend running early games up until mid 1988 would I recommend an earlier revision and Kickstart, and then that setup would be perfect for that application.

I recommend 1.3 or 3.1 over any other Kickstart version for the A500.

It's unusual for an Amiga or motherboard to be sold with an empty Kickstart socket. All custom chips removed, sure, but with only the ROM removed, why?

I have a feeling Gary (upper chip here) or something related to the ROM socket is at fault, rather than which version of Kickstart is used.

I understand the purple screen color is with 1.3 in the socket, since 3.2 won't work on unexpanded (and some expanded) A500s. You probably already know what to expect: dark, medium, light gray and then the disk hand on a white background.

(General advice): I would start with everything detached but PSU and monitor. Then I would make 1 change to the setup at a time to determine what's wrong. You can then swap over socketed chips from a known good Amiga, one at a time, and observe any changes in boot-up. This method is very often successful, because all the components involved in boot-up are solid-state, apart from the PSU.

A chip is missing. 74157 is a mux, which could be used for addressing the ROM.

[Planetinfinity]

Hello,

in the meantime we tested a couple of things. So I will quickly describe the tests and the results.

1. Check with diagrom 1.2.1 -> no output

We received the diagrom we ordered. One thing I am not sure is whether I really have to (hard) push the rom to the socket because the diagrom has already a socket and even with medium preasure I was not able to push the ROM into the mainboard socket (03_diagrom_2.jpg).

However I also hope that the direction of the ROM was correct. We followed the direction of the hole on the mainboard socket.

However usually we didn't get any output but for one test we saw a red screen output.(04_diagrom_output.jpg).

Unfortunately I don't have a serial 25port cable to 9port cable and an adapter from 9 port to usb at the moment in order to see the output via serial interface.

2. Check with ROM 1.2 -> output
We had the chance to use a kickstart ROM 1.2 in our mainboard. Afterwards we were able to see the kickstart 1.2 message at the screen (06_rom12_output.jpg).

3. Check with ROM 2.0.4 -> no output
We bought kickstart rom 2.0.4 but we are not able to see any output (08_rom204_output.jpg).

Hopefully this clarifies the current status of our tests.

[Jope]

That 2.04 ROM only contains half of the kickstart. It is the high ROM from an A3000.

You'll need to find an A500/600/2000 Kick ROM.