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Author Topic: Amiga 4000 Won't boot  (Read 5623 times)

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Offline Ami_GFXTopic starter

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Amiga 4000 Won't boot
« on: July 04, 2011, 01:39:38 AM »
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.
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A2500 owned since 1993 with A2630/DKB 2632, DKB Megachip, GVP EGS Spectrum, A2320 and GVP HC+8 on the inside and a DCTV on the outside. A4000D with CSPPC, Cybervision 64 and a Flicker Magic flicker fixer. A4000T Toaster Flyer & CSMKII. All systems completly retro and classic and mostly used to do geometic art as in my avatar.
 

Offline Ami_GFXTopic starter

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Re: Amiga 4000 Won't boot
« Reply #1 on: July 04, 2011, 02:58:15 AM »
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.
« Last Edit: July 04, 2011, 03:09:52 AM by Ami_GFX »
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A2500 owned since 1993 with A2630/DKB 2632, DKB Megachip, GVP EGS Spectrum, A2320 and GVP HC+8 on the inside and a DCTV on the outside. A4000D with CSPPC, Cybervision 64 and a Flicker Magic flicker fixer. A4000T Toaster Flyer & CSMKII. All systems completly retro and classic and mostly used to do geometic art as in my avatar.
 

Offline Ami_GFXTopic starter

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Re: Amiga 4000 Won't boot
« Reply #2 on: July 04, 2011, 04:23:57 PM »
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.
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A2500 owned since 1993 with A2630/DKB 2632, DKB Megachip, GVP EGS Spectrum, A2320 and GVP HC+8 on the inside and a DCTV on the outside. A4000D with CSPPC, Cybervision 64 and a Flicker Magic flicker fixer. A4000T Toaster Flyer & CSMKII. All systems completly retro and classic and mostly used to do geometic art as in my avatar.
 

Offline Ami_GFXTopic starter

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Re: Amiga 4000 Won't boot
« Reply #3 on: July 25, 2011, 02:16:02 AM »
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.
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A2500 owned since 1993 with A2630/DKB 2632, DKB Megachip, GVP EGS Spectrum, A2320 and GVP HC+8 on the inside and a DCTV on the outside. A4000D with CSPPC, Cybervision 64 and a Flicker Magic flicker fixer. A4000T Toaster Flyer & CSMKII. All systems completly retro and classic and mostly used to do geometic art as in my avatar.
 

Offline Ami_GFXTopic starter

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Re: Amiga 4000 Won't boot
« Reply #4 on: July 25, 2011, 04:38:50 AM »
Quote from: HammerD;651552
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.
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A2500 owned since 1993 with A2630/DKB 2632, DKB Megachip, GVP EGS Spectrum, A2320 and GVP HC+8 on the inside and a DCTV on the outside. A4000D with CSPPC, Cybervision 64 and a Flicker Magic flicker fixer. A4000T Toaster Flyer & CSMKII. All systems completly retro and classic and mostly used to do geometic art as in my avatar.
 

Offline Ami_GFXTopic starter

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Re: Amiga 4000 Won't boot
« Reply #5 on: August 03, 2011, 12:48:58 AM »
Quote from: HammerD;651552
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.
« Last Edit: August 03, 2011, 12:58:10 AM by Ami_GFX »
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A2500 owned since 1993 with A2630/DKB 2632, DKB Megachip, GVP EGS Spectrum, A2320 and GVP HC+8 on the inside and a DCTV on the outside. A4000D with CSPPC, Cybervision 64 and a Flicker Magic flicker fixer. A4000T Toaster Flyer & CSMKII. All systems completly retro and classic and mostly used to do geometic art as in my avatar.
 

Offline Ami_GFXTopic starter

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Re: Amiga 4000 Won't boot
« Reply #6 on: September 05, 2011, 05:48:17 PM »
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.
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A2500 owned since 1993 with A2630/DKB 2632, DKB Megachip, GVP EGS Spectrum, A2320 and GVP HC+8 on the inside and a DCTV on the outside. A4000D with CSPPC, Cybervision 64 and a Flicker Magic flicker fixer. A4000T Toaster Flyer & CSMKII. All systems completly retro and classic and mostly used to do geometic art as in my avatar.
 
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