Amiga 4000 boots and works on RTG but black screen on AGA

[reflex]

Hello

i hava an Amiga 4000 desktop inside a microbic tower with a CyberstormPPC improved by statchu100.
IT has a ZZ9000 and two more grafic boards on the mediator (a voodoo 3 and a Radeon 9200).
Now the problem is that the computer boots up nicely with RTG modes, but i cannot get any display on AGA modes, i cannot get any Early Startup menu too.
Id i unplug mediator and all the boards the screen starts low grey then light grey, the floppy stars clicking but i don't get the purple screen that invites me to put a floppy inside.
If i boots with floppy inserted it loads workbench (i can hear the noise) but the screens stays black.

It looks like the computer works but there is some kind of problem with the chips or memory.
Am i right?
What did happen?

[alexh]

I'd bet money your display does not support 15KHz @ 50Hz

[reflex]

Originally Posted by alexh

I'd bet money your display does not support 15KHz @ 50Hz

yes it does.
it's a TV/Monitor and anyway ZZ9000 has a scandoubler.
I used SCART port too and everything was working fine until a few days ago.

[Channel-Z]

The problem with the Mediator setup is you loose the Amiga's video passthrough slot on the original DB, The ZZ9000 plugs into this port so Amiga native RGB modes can pass thought the ZZ9000 and out the HDMI to your monitor.

[alexh]

If you had a chip RAM problem you'd get a GREEN screen during boot. A ROM issue a RED screen.

Looks like something affecting the video out circuit. That on the A4000 is coming from the Alice chip.

Perhaps a broken track around the Alice chip? Did you ever have an Indivision scandoubler or something which plugs onto the Alice?

Try to use a DiagROM?

https://www.diagrom.com/

[alexh]

Originally Posted by Channel-Z

The problem with the Mediator setup is you loose the Amiga's video passthrough slot on the original DB

Mediator A4000 D(i) has a Video Slot

[reflex]

I know the meaning of the colors of the screen but i know that they are not 100% reliable.

I guessed an hardware problem but i never had an indivision or anything like that, just a Picasso IV in the past and now the ZZ9000
I have a ZIP drive and severa different amiga installation in different autobot ZIP disk, i have a 3.1 installation and tried a boot and it worked once, i got some glitches on the screen opening the drawers but when i dragged the screen down everything become black.

Originally Posted by alexh

If you had a chip RAM problem you'd get a GREEN screen during boot. A ROM issue a RED screen.

Looks like something affecting the video out circuit. That on the A4000 is coming from the Alice chip.

Perhaps a broken track around the Alice chip? Did you ever have an Indivision scandoubler or something which plugs onto the Alice?

Try to use a DiagROM?

https://www.diagrom.com/

[alexh]

Originally Posted by reflex

I know that they [Kickstart ROM ChipRAM tests] are not 100% reliable.

It could be ChipRAM but it would have to be pretty catastrophic to black screen. Battery leaks on the A4000 are known to affect the area where ChipRAM is. Even if the leak was many years ago and the battery has since been removed if the alkali is not neutralised it can continue to eat tracks, especially under sockets and chips. Also the clips for the SIMM sockets are known to weaken.

You could look around that area, perhaps apply a small amount of pressure to the ChipRAM SIMM while booting. See if anything helps.

DiagROM is your best chance of diagnosing a ChipRAM memory fault.

[reflex]

Originally Posted by alexh

DiagROM is your best chance of diagnosing a ChipRAM memory fault.

i used Diagrom.

Chip memory is ok, but RBG test fail most of the times.

[alexh]

I'm afraid I don't know what that test does and what a fail means

[Kin Hell]

RGB test failing in what manner?

[reflex]

Originally Posted by Kin Hell

RGB test failing in what manner?

it displays the colors, then glitches and finally i get black screen.

[Kin Hell]

Have you tried stripping the Amiga back to a stock A4KD?

Have you tried another RGB cable?

Does the Caps Lock LED stop lighting up for pressing every one second?

[reflex]

Originally Posted by Kin Hell

Have you tried stripping the Amiga back to a stock A4KD?

Have you tried another RGB cable?

Does the Caps Lock LED stop lighting up for pressing every one second?

it's not a cable-related problem as sometimes the AGA output works but then glitches. Why do the case influence the custom chip output?

[Kin Hell]

Originally Posted by reflex

it's not a cable-related problem as sometimes the AGA output works but then glitches. Why do the case influence the custom chip output?

But have you tried running AGA on your Motherboard with nothing else set up in it?

For my money & only because you mention Voodoo & Radeon in the same breath....

Either/Or require a fresh install. - This means you can not use Voodoo & Radeon on a single Amiga setup. Both require their own "Fresh" install.

So...... Have you tried running AGA on your Motherboard with nothing else set up in it? - Hard drives out, boot from floppy... Does AGA work?

[reflex]

Originally Posted by Kin Hell

But have you tried running AGA on your Motherboard with nothing else set up in it?

For my money & only because you mention Voodoo & Radeon in the same breath....

Either/Or require a fresh install. - This means you can not use Voodoo & Radeon on a single Amiga setup. Both require their own "Fresh" install.

So...... Have you tried running AGA on your Motherboard with nothing else set up in it? - Hard drives out, boot from floppy... Does AGA work?

hello.
I tried without any board and any HD, there is the problem even with the insert floppy animation at boot up.

[van_dammesque]

Use a volt meter and check if the motherboard is getting the correct voltages to try rule out the PSU. Use extreme caution!

[reflex]

Originally Posted by van_dammesque

Use a volt meter and check if the motherboard is getting the correct voltages to try rule out the PSU. Use extreme caution!

3 years ago i bought a this 500watt ATX PSU,
https://www.amazon.it/gp/product/B01...0?ie=UTF8&th=1

i guessed it was a good one, is that really possible an output issue?.

Anyway i have a multimeter, do i have to check the 5v tensione on the molex connector or somewhere on the MoBo?

[RetroPassionUK]

Originally Posted by reflex

Hello

i hava an Amiga 4000 desktop inside a microbic tower with a CyberstormPPC improved by statchu100.
IT has a ZZ9000 and two more grafic boards on the mediator (a voodoo 3 and a Radeon 9200).
Now the problem is that the computer boots up nicely with RTG modes, but i cannot get any display on AGA modes, i cannot get any Early Startup menu too.
Id i unplug mediator and all the boards the screen starts low grey then light grey, the floppy stars clicking but i don't get the purple screen that invites me to put a floppy inside.
If i boots with floppy inserted it loads workbench (i can hear the noise) but the screens stays black.

It looks like the computer works but there is some kind of problem with the chips or memory.
Am i right?
What did happen?

Sounds like chip/track damage going to U976 which of course is near the battery. Missing AGA, that's your chip you need to check, well replace and check the tracks all around it.