Amiga 4000 Won't boot

[Ami_GFX]

I just got a new monitor to test with my Amigas and my A4000 which had been sitting idle--the last time I turned it on was several month's ago--wouldn't boot. The power light is solid green, the hard drive spins, the hard drive light comes on solid orange for about a minute and turns off, the and nothing happens afterwards. I tried booting from a 3.1 install floppy and nothing happened at all with the floppy drive. I took it apart and cleaned contacts and connectors, tried booting it with nothing but the MB, 3640, and floppy attached, nothing. The caps lock light turns on and I can reboot with ctrl A A. Unfortunately, I don't have a 15khz monitor on hand to see what the screen is doing so I have no idea how far it is getting in the boot sequence. I've been using it with a Picasso II.

I removed the battery when I got it and there was no new corrosion around where it was or any caps that looked like they leaked. The 3640 and MB look very clean all in all. There was just a small amount of dust and nothing that was obviously wrong.

[smerf]

Hi,

@AMI__GFX

Welcome aboard to Amiga, FNG.

OK, lets get started, you say you have been using a Picasso II card, on this card there should be a 23 pin amiga video connector to a vga connector hooked up. As you are looking at your computer from the back this connector should be hooked up from the Amiga 23 pin video out to the left hand vga port on the back of the Picasso II, a regular vga monitor or lcd screen should be plugged into the right side of the Picasso II card. I use a GVP IV 24 card so I use a VGA to VGA plug on my Picasso II. Anyhow without this connector the Amiga won't show anything.

Another thing you can do is try the Amiga 520 video adapter which takes the 23 pin output and converts the video to composite out.

It sounds like your Amiga 4000 is booting up, you just can't see the video.

smerf

[Ami_GFX]

A little more detail about the hardware. This is a Toaster 4000 Amiga that originally belonged to a Technical College in Pennsylvania. I have the 23 pin connector connected to a Sync Strainer and the 15 pin out of the Sync Strainer connected to the Picasso IIs input. It works well with my LCD monitors in both Picasso and DBL NTSC modes. When the Toaster is active and in genlock mode, I get composite out of 15khz Amiga modes from it.

Unfortunately I sold my 1080s monitor and an A520 would be the cheapest solution to see what's going on. I found a couple on ebay and put them on my watch list but it's going to take me some time to get one.

I don't think it is getting to the insert floppy screen because nothing happens when I put a floppy in, even with all the Zorro boards and IDE drives removed. It is getting somewhere in the boot sequence, far enough to recognize the keyboard. I think it might be a green screen. When I got it, it had some battery leakage and the MB and first simm slot had some corrosion from it and I got a green screen. I removed the battery and cleaned the simm socket and MB and it worked from then on. It doesn't look like there's been any further corrosion from any residue from the battery. The area around the battery on the MB looks clean. I took out all the simms and cleaned them and the sockets with contact cleaner. Possible that the chip ram simm has gone bad but not too likely. I've got a box of unsorted 72 pin simms and I might have one I can swap to test this.

[Dandy]

A little more detail about the hardware. This is a Toaster 4000 Amiga
...
Unfortunately I sold my 1080s monitor and an A520 would be the cheapest solution to see what's going on. I found a couple on ebay and put them on my watch list but it's going to take me some time to get one.

There's a small chance that your Miggy is getting to the insert floppy screen, but...

I don't think it is getting to the insert floppy screen because nothing happens when I put a floppy in,
...

...as nothing happens on inserting a floppy disk I highly doubt that.

From my A4000 with CSPPC I know this sort of problem.
In intervals of 1 - 1.5 years it simply refuses to boot (or it boots and freezes shortly after).
Reason here is that the contacts between motherboard and CPU board tend to corrode over time.
Up to now I always could solve this problem by cleaning the contacts between motherboard and CPU board with commercially available contact sprays.
Have you already tried this?

When I got it, it had some battery leakage and the MB and first simm slot had some corrosion from it and I got a green screen. I removed the battery and cleaned the simm socket and MB and it worked from then on.

I threw out my battery as well when I noticed it started leaking (luckily before the mobo was contaminated). I didn't replace it and automatically retrieve the actual date/time from the web as soon as I go online instead.

It doesn't look like there's been any further corrosion from any residue from the battery. The area around the battery on the MB looks clean. I took out all the simms and cleaned them and the sockets with contact cleaner. Possible that the chip ram simm has gone bad but not too likely. I've got a box of unsorted 72 pin simms and I might have one I can swap to test this.

You should try to clean the connectors between CPU board and mobo as well this way...

[Ami_GFX]

I tried a different Chip Ram Simm, no difference. I think the CPU is working from having the caps lock light come on and being able to reboot from the keyboard. I took the 3640 out yesterday and there was no obvious corrosion on the connector. The power supply voltages check out ok with a voltmeter. There are 2 NTSC A520s on eBay that end in a few days. I have a similar device for the Atari St and I might be able to rig up a cable for it with the video out dongle from a dead ST MB I have and either a VGA or 23 pin lead--I have both in my scrap pile. It seems to be getting somewhere in the boot cycle but I have no idea how far.

[smerf]

I tried a different Chip Ram Simm, no difference. I think the CPU is working from having the caps lock light come on and being able to reboot from the keyboard. I took the 3640 out yesterday and there was no obvious corrosion on the connector. The power supply voltages check out ok with a voltmeter. There are 2 NTSC A520s on eBay that end in a few days. I have a similar device for the Atari St and I might be able to rig up a cable for it with the video out dongle from a dead ST MB I have and either a VGA or 23 pin lead--I have both in my scrap pile. It seems to be getting somewhere in the boot cycle but I have no idea how far.

Ok, We are up to the floppy drive, do you have any other Amiga's that you know work, try you floppy in them to make sure it will boot up, (luckily I have an A1200 for my testing) Once you know that you have a good floppy, take everything out of your Amiga, get it down to the barest minimum. If you have a A520 plug that in and get a good old composite device, monitor, TV even a vcr (hopefully you still have one (but do we remember how it works),

look at your floppy drive ribbon, is it plugged in right, is the red line on the floppy connector connected to pin 1. L

next look at the back of the floppy, is the power plug in right, is the ribbon cable plugged into all pins on the drive.

I also have a Toaster 4000, every now and then, it stops working, and I go through the same ritual, I open the box take it down to bare minimum, then I start pressing on chips, wiggling the ribbon cable on the floppy, taking off and putting back on the power cord, and reseating the accelerator card. I swear that all A4000 have poor solder joints, because sometimes it takes an hour of playing around with objects in the floppy area to get it working again.

I don't think it is really dead, just something that came loose, mine does this at least once every 3 months.

[Dandy]

...
I took the 3640 out yesterday and there was no obvious corrosion on the connector.
...

The corrosion isn't necessarily obvious - in my A4k it never was obvious.
But each time I treated contacts in the connector between CSPPC and mobo with commercially available contact sprays, the system worked flawlessly afterwards for the next 1 - 1.5 years...

[Ami_GFX]

Thanks for all the help. I suddenly got very busy and haven't had time to take my A4000 apart. I lost several eBay auctions for an A520 and this morning bid on a DCE Flicker Magic internal scan doubler, left for work, and when I came home was surprised to find that I had won it for a little more than the minimum bid so when it arrives, I will take the A4000 apart and start working on it again. Once again, thanks to all who have posted their advice.

[HammerD]

Thanks for all the help. I suddenly got very busy and haven't had time to take my A4000 apart. I lost several eBay auctions for an A520 and this morning bid on a DCE Flicker Magic internal scan doubler, left for work, and when I came home was surprised to find that I had won it for a little more than the minimum bid so when it arrives, I will take the A4000 apart and start working on it again. Once again, thanks to all who have posted their advice.

An easy way to test if the 68K is responding (thus the CPU card working) is to keep pressing the CAPS LOCK key - the LED should blink on and off as you press the button.

Keep pressing it.  If it eventually stops toggling from on and off then the CPU is not responding.

If the CPU is working, the LED will keep toggling on and off for as long as you keep pressing the CAPS LOCK key.

[Ami_GFX]

An easy way to test if the 68K is responding (thus the CPU card working) is to keep pressing the CAPS LOCK key - the LED should blink on and off as you press the button.

Keep pressing it.  If it eventually stops toggling from on and off then the CPU is not responding.

If the CPU is working, the LED will keep toggling on and off for as long as you keep pressing the CAPS LOCK key.

It passes that test. The CPU seems to be working. It looks more like a memory or drive controller problem. With no way to see the RGB boot video out, it has been hard to diagnose. I'm happy to get the internal flicker fixer which should not only give me a way to see the RGB boot video out but be a major upgrade when I get it fixed.

[Ami_GFX]

An easy way to test if the 68K is responding (thus the CPU card working) is to keep pressing the CAPS LOCK key - the LED should blink on and off as you press the button.

Keep pressing it.  If it eventually stops toggling from on and off then the CPU is not responding.

If the CPU is working, the LED will keep toggling on and off for as long as you keep pressing the CAPS LOCK key.

It looks like you're right. I got the flicker magic installed and I got a totally black screen. I did the caps lock test and after about 6 presses it went off and wouldn't turn on again. I took out the CPU card and I got the exact same result with the caps lock test so it looks like the CPU card has failed. I'm dousing the contacts with cleaner and seeing if it responds but I see a trace of corrosion by one of the capacitors and that might be the problem.

[Ami_GFX]

It's working again. I checked the capacitors on the A3640. It was one of the rev 3.1 A3640s with 3 capicitors inserted backwards but the leaky cap was, ironically, one of the 2 inserted correctly. I removed all 5 capacitors, cleaned up the circuit board and soldered on good capacitors but still no go. I bought another A3640 and tested it, and my A4000 came back to life. I carefully removed the bad caps on my new A3640 and soldered in new bipolar 22mf 25 volt capacitors so this won't happen again.

The only issue now is that the Flicker Magic and the Video Toaster card don't work well together at all but that's something for another post.