Black screen on 3000

[matt3k]

I recently replaced the battery on 3000, that already suffered damage long ago.  (My friends were neglectful with take care of their machines ).

Prior to replacing the battery everything was working perfectly.

I replaced the battery and again it worked fine.  After about 2 hours, we were given a black screen.

The power supply and roms are good, and I reseated all the IC's.

Now all I get is an dim power led and a flash on the monitor if I switch on and off the deinterlacer.

Any thoughts?

[matt3k]

Try removing all SCSI devices (external ones first, then internal).

This is probably not the cause of your problem, but it's worth a try.

I had an Amiga 3000 refuse to start up and behave very strangely when external devices were attached (i.e. the power button would not even turn the machine on when an external device was attached and powered up first).

Thanks Ral-Clan for the idea.

I already have all SCSI devices removed.

Wish it was that one...

[matt3k]

I hit both tuning pods, they had 2 connections each.  Replaced many custom chips.

The Keyboard light blinks when I turn it on, and I can turn caps on and off.

Still black screen, with dim power led, the monitor turns on from signal being sent.  turning on and off the deinterlacer still flickers the screen.

Any other ideas?

That happened to me once also. The tuning pod where it was mounted had a broken solder joint.. there is 3 points i believe where it is mounted, might wanna check that.
Do you hear the hard drive spin up? what kind of drive is it.. Maybe it needs the scsi prefs to be set up again. I had to put a boot delay of 5 secs to give spin up time for my hd. You might of lost settings when battery died? (that could be a long shot just putting it out there).  Check to see if floppy connections too are all in place. Neve know.

lost

[matt3k]

There is no composite out. The high-end Amiga 3000 and 4000 models lacked composite output of any kind.

could use the a520 modulator and see if it works with that. I bet its the zip ram.


lost.

The spec is a stock 3k @25MHz, 8 megs zip fast ram, 2 megs chip, latest chipset for everything.

I tried removing all fast and 1 mb of chip with the same result.

Not sure if I hook up my a520 if it will show anything, since the power led isn't cycling as a normal startup.  It starts and stays a dim green.

It was running fine for 2 hours and then it just stopped.  None of the chips seem to be running hot.

A real wing dinger here...

[matt3k]

Check the motherboard crystal, its not far above the 68030 chip. Sometimes they can work loose in the holder.

Az

The crystals on my motherboard are surface mounts.  I did hit the solder, to be sure...

[matt3k]

have you looked at this page ?

http://amiga.serveftp.net/A3000_HardwareGuide/booting-problems.html

lost

edit: by chance is all jumpers on motherboard in place???

I will look at them, but it was running fine for 2 hours, so I don't think that could be it.  But, here hoping ...

Yes, I went to the link for suggestions.  I should test the caps locks to see if the cpu if responsive.  The caps lock works but I have to do it multiple times to see if cpu is working.

Thanks for all the help.

[matt3k]

Is SCSI termination correct?  Even with no drive I had black screen boot issues if there was no termination.

Also my rev motherboard required a SCSI drive attached or I would get a black screen on boot.

Yes, termination is fine.  

I have removed the riser card to test so it should give a flashing yellow screen, it doesn't even get that far.  So it is early on that it fails...

[matt3k]

I tested the caps lock test for the cpu.

After 6 times pressing the caps lock, it stops working.  So the CPU isn't working.

[matt3k]

check power supply maybe. See if there is a enough voltage.. dunno grasping at straws now sorry. Reset roms? swap around cia chips? never know. Any blinks at all from the caps?

edit again lol: reading here it says :"Response from caps lock key means CIA and the CPU works.[5]"
http://en.wikipedia.org/wiki/Kickstart_%28Amiga%29
So if pressing it on and off and light goes on and off does that mean the cpu still works?

lost

I tried multiple power supplies so that's not it.  Tried different roms.  Will try new CIA's next.

The cap lock stops responding after pressing it 6 times.  So I'm guessing the CPU isn't working or working yet?

[matt3k]

Update:

Took all chips out and cleaned sockets.  Looked over well, the mb is is really good shape so I didn't see anything suspect.

I measured The clock chip pin 2 and ground and getting 5 volts, so I don't thinks it's low level at this point.

Do any troubleshooting or measuring spots guides exist for the amiga 3000?  I really need to measure voltages to troubleshoot at this point.

Kind regards,

Matt

[matt3k]

Whoever wrote that Wikipedia detail based on my article seems to have misinterpreted what I wrote.  I've since updated the Wikipedia page as follows:

"When the caps lock key is repeatedly pressed approx. 10 times, the caps lock LED turning on and off each time indicates the CPU is correctly reading the CIAs. If the caps lock LED sticks on or off, the CPU is not servicing CIA interrupt requests."

Feel free to re-word things if I've made an arse of explaining it.

Looks like your A3000 has some fundamental hardware issue going on.  The next easiest thing to do is look at the /ROMEN line (active low) to see if the CPU is at least attempting to access the ROMs and that the system address decoder is working.  You'll need an oscilloscope for this, or you might get a rough idea by using a logic probe.

If /ROMEN has no activity, you'll need to look closer at the CPU support and control.  e.g. make sure reset is high, all system clocks and clock dividers are working normally.

If you have OS2.x or 3.x in ROM and the Zorro riser card is not fitted, the CPU will generate an exception (yellow screen), but that happens quite a bit later during ROM execution; I think when expansion.library gets called.  Most of the hardware will need to be working for it to get this far.

Since the system was working before you replaced the battery, you've probably disturbed something.  Often this is caused by dodgy IC sockets.  Did you check for corrosion in the Densie/Paula sockets? (green/blue terminals)

Thanks for the great feedback.

I did have some green on a few spots in the denise socket.  I used a toothbrush and vinegar and scrubbed the area and rinsed it in water.

I then used a fiberglass pen to fully clean it and then sprayed all the sockets with circuit board cleaner.

At this point the board looks new off the factory line.

I did notice that underneath the board there was a few white spots.  I don't know if this is because that is where it laid on the cardboard  as it dried or if it might be a cap issue.

[matt3k]

Glad you brought your back to life!!!

I already measured for short, +5v on mb to ground gave a resisted measurement, so not so easy in my case...

Thanks for the idea though.

Your problem happened to me last weekend to me when i replaced the battery in my a3k. I just about crapped my pants! I removed the board again after and put it back in again REAL carefully and all worked again.. I think (well at least with me) it might of been touching the case some how. Maybe poked thur the plastic shielding at the bottom maybe, not sure what to tell the truth, but it worked again. So maybe it was grounding out somewhere. Did the 6 presses of the caps and black screen. Could be the same thing?

lost