Amiga 3000 will not boot - no video

[simon_m74]

Hi
I have 2 Amiga 3000`s that both seem to do nothing at all.

No video output at all.

When doing a keyboard reset - the power LED does not flash - stays on.

Tried diagrom, KS3.1 - both known working.
Boards are Rev9.#

One of these Amigas used to give a black screen but nothing else - but nothing at all now.

Any ideas where to start looking?

what are the minimum chips to have in when trying to boot with diagrom?

[matt3k]

Look for bad traces around the battery.
Replace the gals.
Make sure the jumpers are set correctly.
Make sure chips are all seated.

The led should go low to high intensity.

[SpaceAce]

Originally Posted by matt3k

Look for bad traces around the battery.

If the original battery is still in there, my guess is that it has leaked all over the motherboard and corroded through it. New board time.

[simon_m74]

Battery is out on both.
Both have a little corrosion, but I have working boards with more damage.
I will check for any damages in traces there though.

I`m sure all jumpers are ok, as I compared them to my working one.
Chips have all been pressed in firmly, and in some cases cleaned legs and sockets. (Paula and Denise)

LED has no brightness change at all while system is powered - even on keyboard reset

Gals...?
Which ones... Unless taking from a `working` board, which I`d rather not, where can I get some from?

[Warty]

Have you tried swapping the PSU from the one you have that works? Or measuring the voltage on the different lines?

I do suspect the battery corrosion of course but….

Err, you’ve tried both video outputs with same result?

[simon_m74]

Good question on PSU.

As I have designed daughterboard that accepts an ATX, I`ll try that.

[amiman99]

Maybe CPU is bad, my A3000 CPU is bad, it happens.
Try external CPU board, change jumpers to enable that.

[DarrenHD]

Originally Posted by amiman99

Maybe CPU is bad, my A3000 CPU is bad, it happens.
Try external CPU board, change jumpers to enable that.

Yes if no power LED dim on start it can be CPU not responding. Try it with a 3640 accelerator card and change the jumpers for that, see if it changes things.

[simon_m74]

I have tried the accelerator on both... still blue / no video.

[Warty]

When you say "blue"... that's the screen is blue? So there is video?

You also mentioned the LEDs don't change, but does that mean it's showing a solid green power LED?

Can you pull the PSU power plug from the board, and stick a multimeter in it and measure the various voltages? I would guess the LEDs are running off the +5, but there should be -5, +5, +12, and -12 (from memory). having the PSU go back would not be very surprising.

[simon_m74]

I`ll check PSU soon.
blue : the TV `no signal` colour... the Amigas are outputting nothing.

[mousehouse]

Is the daughter-board installed? I think the 3000D does not boot without it.

[Warty]

I believe you get a video signal with a 3000 even when the daughter board is removed. It won’t boot of course.

You might try swapping a known good Denise, etc in. Let’s hope it’s the PSU.

[DarrenHD]

Just to throw this in here. I had similar symptoms (black screen, no boot) on one of my A3000's and it turned out it was the SuperDMAC chip. It was dead. Replaced it and then it worked fine.

Darren

[simon_m74]

I`m working on finishing my amiga 3000 checkmate kits at the moment - plan to reinvestigate the other amigas when i`m done - but maybe having an extension to the house sooner than later - so that will mean all workspace out of action till complete.