Fun, Fancy, Frustrating, Floppy Drives - A4000D - Amiga 4000D

[dingebre]

I recently acquired an A4000D, Rev B motherboard in amazing condition. It was restored very nicely and was working great (notice "was")

Well, it actually is still running great with a small caveat. I can't seem to get the floppy drive configured properly. Background:

• The system came with a CF IDE disk with OS 3.1 and 3.9 installed with 3.1 ROMs.
• It had a CD drive.
• It had a stock 68040 Amiga 3640 CPU card.
• It had a 256 Mb RAM card (Individual Computers).

Booted, ran everything great.

I did the following:

• Added a MTN ZZ9000 RTG card and audio card.
• Installed 3.2.2 ROMs.
• Installed the new A3660 CPU card.
• Configured a new CF card with OS 3.2.2.1.

The PSU also happened to blow up (see here: https://forum.amiga.org/index.php?topic=76195.0). I repaired the PSU and the system seemed to be ok until I reconnected the floppy drive.

After reconnecting the floppy and CD ROM drive, I got a software error during startup. I had NOT changed any jumpers or anything other than installing the 3660, ZZ9000, and ROMs. I read the manual and I have to believe I'm not understanding something I thought I did understand. Right now, jumper J351 is "open" and jumper J352 is set to 1-2 which I understand is an internal DF0: (Changing it to "EXT" didn't really change much).

I have been able to get it booting and recognizing the floppy, sort of. Here are some details of what I've investigated and identified:

• I disconnected the CD ROM and floppy and it booted fine.
• Took turns with the CD ROM drive and floppy drive connected/disconnected and saw it was the floppy drive causing issues.
• I tried the A4000 floppy in my A3000 and it worked fine.
• I tried the floppy from my A3000 in the A4000 and it behaved the same as the A4000 floppy.
• I tried a GoTek on the A4000 and it worked.
• If I install a jumper on J351, DF0: is recognized but I get an "Unreadable DF1:" icon on the workbench.
• If I set the jumper on the floppy itself to "DF1:" the floppy is recognized as DF1: regardless if I use the middle connector or end connector with or without jumper J351 installed.
• I can pair the floppy with the GoTek and set either one to DF0: and the other to DF1: and the system sees them how they're jumpered, i.e.: DF0: and DF1:, regardless which one is on the middle connector and which is on the end connector.
• Jumper J352 doesn't seem to affect what is going on.
• Jumper J351 does seem to matter. I get the best behavior when it is not installed and I have both the floppy and GoTek.
• The external floppy port seems to work fine, at least with the GoTek. It didn't seem to recognize a real floppy drive.
• I tried to go back to 3.1 and am getting similar behavior.

Now for the final weirdness.

• I can't boot from a floppy or the GoTek regardless which one is DF0: or DF1:
• I can't double click and hold the mouse buttons and boot into the boot selector screen (sorry, I can't remember the proper name). That is, I hold down both mouse buttons and the system just won't boot. The power light just flashes. This occurs regardless the floppy configuration.
• I can get it to boot and the system is stable by tinkering as described above. However, it won't boot from the floppy or GoTek nor can I do a double mouse click on power up to select boot options.
• When I have the configuration such that is is seeing the floppy and/or the GoTek, the system reads and writes to them without issue.

I would greatly appreciate any thoughts or ideas here. I strongly suspect I'm missing something simple.

Thanks for your time and ideas!

David

[Boing-ball]

From what you are describing. The PSU when it blew might have done damage to one of CIA chips which governs I/O. There are 2 located above the IDE and floppy pins on the mainboard.
Any chance of getting hold of some DiagROMs and checking the CIAS are functioning?
Would say AmigaTestKit, but you don’t have any floppy drives booting.

[dingebre]

From what you are describing. The PSU when it blew might have done damage to one of CIA chips which governs I/O. There are 2 located above the IDE and floppy pins on the mainboard.
Any chance of getting hold of some DiagROMs and checking the CIAS are functioning?
Would say AmigaTestKit, but you don’t have any floppy drives booting.

Interesting. I don't have any DiagROMs handy, but I think I've seen them for sale. I'll look into this and maybe buy a couple of CIAs just in case.

Thanks
David

[dingebre]

From what you are describing. The PSU when it blew might have done damage to one of CIA chips which governs I/O. There are 2 located above the IDE and floppy pins on the mainboard.
Any chance of getting hold of some DiagROMs and checking the CIAS are functioning?
Would say AmigaTestKit, but you don’t have any floppy drives booting.

I ordered a set of DiagROMs and a couple of CIAs, just in case. I need to do a little more reading on the operation of the CIAs, but from the little I know, your thought the PSU blowing up did take a CIA with it is certainly worth checking. The PSU is definitely something that "changed" between when it was working and now

 I'm not sure now how thoroughly I tried booting from the external port. I'll give that a more concentrated try tomorrow. If I can get something to boot, I'll throw AmigaTestKit in and see.

David

[Castellen]

What's the floppy drive type in your A4000, one of the standard Chinon models?  They need a straight wired 34-way cable, i.e. no twists.  Which should be what you have already.

Have you tried another 34-way cable?  Intermittent IDC crimp connectors is a fairly common problem that can develop while removing the cable, and that can cause any number of problems with the floppy drive.

I'm not sure how much DiagROM would help you at this point, though Amiga Test Kit is a good idea.  You don't need a working floppy drive to run it.  Providing you can get the executable onto the hard drive, you can run it directly from there in order to further test the floppy drive interface.  It works very well; you'll need a fairly good understanding of how the floppy drive interface works in order to test it and interpret what you're seeing.  Fortunately it's not complicated.

I'd suggest finding exactly which input/output isn't working before ordering expensive parts and blindly replacing things, you don't want to potentially introduce new problems into the mix.  Besides, you might find it's just a $1 tri-state buffer that's damaged.

[dingebre]

What's the floppy drive type in your A4000, one of the standard Chinon models?  They need a straight wired 34-way cable, i.e. no twists.  Which should be what you have already.

Have you tried another 34-way cable?  Intermittent IDC crimp connectors is a fairly common problem that can develop while removing the cable, and that can cause any number of problems with the floppy drive.

I'm not sure how much DiagROM would help you at this point, though Amiga Test Kit is a good idea.  You don't need a working floppy drive to run it.  Providing you can get the executable onto the hard drive, you can run it directly from there in order to further test the floppy drive interface.  It works very well; you'll need a fairly good understanding of how the floppy drive interface works in order to test it and interpret what you're seeing.  Fortunately it's not complicated.

I'd suggest finding exactly which input/output isn't working before ordering expensive parts and blindly replacing things, you don't want to potentially introduce new problems into the mix.  Besides, you might find it's just a $1 tri-state buffer that's damaged.

The A4000 drive is a stock Chinon Amiga floppy drive. The A3000 is also a stock Amiga Chinon floppy. I do have the standard two floppy cable. The middle connector is "straight" the end connector has the twist.

I agree with the comment on "blindly replacing things." I have a thing about having spare parts, though I don't mind having a few spare chips, etc. around. Like with my PSU repair, I tested extensively before replacing anything.

I've never been able to get AmigaTestKit to run from the HD. It either brings up the screen and freezes or just a black screen on both my A3000s, and now the A4000.

I can pull the cable from one of my A3000s and give it a go. The fact that the A4000 floppy drive, the GoTek, and the A3000 floppy drive eventually are recognized and seem to read/write and otherwise work fine in certain configurations doesn't seem like a cable problem, though.

When I have a second floppy/GoTek connected, the A4000 boots and the drives are recognized and work. I would like to see if the DiagROM will give me some insight.

Thanks for the help.

David

[dingebre]

What's the floppy drive type in your A4000, one of the standard Chinon models?  They need a straight wired 34-way cable, i.e. no twists.  Which should be what you have already.

Have you tried another 34-way cable?  Intermittent IDC crimp connectors is a fairly common problem that can develop while removing the cable, and that can cause any number of problems with the floppy drive.

I'm not sure how much DiagROM would help you at this point, though Amiga Test Kit is a good idea.  You don't need a working floppy drive to run it.  Providing you can get the executable onto the hard drive, you can run it directly from there in order to further test the floppy drive interface.  It works very well; you'll need a fairly good understanding of how the floppy drive interface works in order to test it and interpret what you're seeing.  Fortunately it's not complicated.

I'd suggest finding exactly which input/output isn't working before ordering expensive parts and blindly replacing things, you don't want to potentially introduce new problems into the mix.  Besides, you might find it's just a $1 tri-state buffer that's damaged.

This is getting more and more curious. I think I need to step back for a bit and regroup and rethink things.

A new cable did nothing to help.

I decided to go back to a configuration that I know was working without any issues. I replaced the 3.1 ROMs, replaced the A3640 CPU card, I installed the CF card with OS 3.1/3.9 on it. It would not boot at all regardless the floppy configuration. Power went low/high, the HD light flickered, then the power light went low/high again quite fast, the HD light flickered for 10'ish seconds then nothing. Nothing on the screen. Put the 3.2.2 ROMs in, the A3660, OS 3.2.2.1 and I could get it to boot again.

If either of you, Boing-ball or Castellen, have an idea, I'd love to hear it (many thanks again for your thoughts you've shared already). I am simply quite ignorant with the specific Amiga architecture and don't quite know where to go now. I am more than 50% convinced (barely, like 50.000000000001%) that when the power supply fried, it did do some damage to the motherboard. At least that's the theory right now, but it sort of works . The fact I couldn't go back to the original working system after the PSU blew up seems to support that conclusion. Hope I didn't fry any of the programmable logic arrays.

I found some schematics and the "Amiga PCB Explorer" which are helping, but I need more foundation I think.

Ah well...

David

[Castellen]

Sounds as though there's more going on than possible floppy drive issues.

At this point I'd suggest testing the following simple as possible configuration:
- v40.68 (OS3.1) ROMs fitted
- A3640 CPU board fitted (both main board clock source jumpers need to be set to EXT)
- Both floppy drive and hard drive disconnected from the main board
- No expansion cards fitted

As above with nothing else connected to the main board except the power supply and the monitor, when you power on the machine, you should eventually get the purple 'insert disk' screen after about 30-40 seconds (of staring at the black screen).  At power on, the power LED should change brightness once.  If you see it flashing as you described, then you probably won't see the 'insert disk' screen, and there's some other hardware problem preventing it from booting.

At this point if you have boot problems, remove all 4 fast memory SIMMs (the 4 nearest the outside of the board), leaving only the innermost chip memory SIMM present.  Repeat the same tests above and see if it boots or not.  If so, you might have a bad fast memory SIMM.

Also try a known good chip memory SIMM if you have a spare (specifically needs to be 2MB, double sided).  As the memory tests in ROM aren't thorough, it can try to boot (and fail) under certain failed memory conditions.

Else there's probably some kind of hardware issue with the main board.  At this point DiagROM would help to see more of what's going on.  The latest version of DiagROM (v1.3) includes good chip memory tests.  If that doesn't narrow it down, then you could send it to me for repair.  I have a run-time hardware debugger that shows the detail of what's happening internally to see where the ROM software is failing, in order to narrow down what area of the hardware is causing issues.

[dingebre]

Sounds as though there's more going on than possible floppy drive issues.

At this point I'd suggest testing the following simple as possible configuration:
- v40.68 (OS3.1) ROMs fitted
- A3640 CPU board fitted (both main board clock source jumpers need to be set to EXT)
- Both floppy drive and hard drive disconnected from the main board
- No expansion cards fitted

As above with nothing else connected to the main board except the power supply and the monitor, when you power on the machine, you should eventually get the purple 'insert disk' screen after about 30-40 seconds (of staring at the black screen).  At power on, the power LED should change brightness once.  If you see it flashing as you described, then you probably won't see the 'insert disk' screen, and there's some other hardware problem preventing it from booting.

At this point if you have boot problems, remove all 4 fast memory SIMMs (the 4 nearest the outside of the board), leaving only the innermost chip memory SIMM present.  Repeat the same tests above and see if it boots or not.  If so, you might have a bad fast memory SIMM.

Also try a known good chip memory SIMM if you have a spare (specifically needs to be 2MB, double sided).  As the memory tests in ROM aren't thorough, it can try to boot (and fail) under certain failed memory conditions.

Else there's probably some kind of hardware issue with the main board.  At this point DiagROM would help to see more of what's going on.  The latest version of DiagROM (v1.3) includes good chip memory tests.  If that doesn't narrow it down, then you could send it to me for repair.  I have a run-time hardware debugger that shows the detail of what's happening internally to see where the ROM software is failing, in order to narrow down what area of the hardware is causing issues.

Thank you for the suggestions. I will certainly try these steps as soon as I can and will report back here. Probably not til over the weekend.

The offer to repair is very generous. If it comes to that, I'll send a D.M. and we can work out the details.

David

[F0LLETT]

Thank you for the suggestions. I will certainly try these steps as soon as I can and will report back here. Probably not til over the weekend.

The offer to repair is very generous. If it comes to that, I'll send a D.M. and we can work out the details.

David

Hi,

I think I may have deleted your last post by mistake, while I was getting rid of that spam thread. If I have, I'm very sorry.

[dingebre]

Hi,

I think I may have deleted your last post by mistake, while I was getting rid of that spam thread. If I have, I'm very sorry.

You did delete it. No worries.

David

[dingebre]

Thank you for the suggestions. I will certainly try these steps as soon as I can and will report back here. Probably not til over the weekend.

The offer to repair is very generous. If it comes to that, I'll send a D.M. and we can work out the details.

David

Don't know if you saw my last reply, it was deleted by mistake (see above).

Basically, I was starting your checklist and when inserting ROMs, one DIP socket cracked and a piece broke off. I think it was still making electrical contact, but I think I'd better replace the sockets first. I ordered some and they came. If this week slows down at all, I'll be able to install them and try your suggestions. I also ordered a "Medusa Retro Scandoubler" to have in case I need it. I don't have an RGB monitor nor a VGA monitor that will sync to 15kHz.

Anyway, I'll report the findings here when I'm done. Early tries (with the sketchy ROM socket) give a black screen with no drives connected. But with the CF "hard drive" it boots and it seems to report the correct FAST memory amount and the extended memory on the ZZ9000 (at least with SysInfo). Noting these were quick and dirty preliminary tests and I will be more careful and thorough after the new ROM sockets.

David

[Castellen]

The offer to repair is very generous. If it comes to that, I'll send a D.M. and we can work out the details.

It's not that generous.  Amiga repairs have been one of my normal jobs for the last 25 years.

Anyway, I'll report the findings here when I'm done. Early tries (with the sketchy ROM socket) give a black screen with no drives connected. But with the CF "hard drive" it boots and it seems to report the correct FAST memory amount and the extended memory on the ZZ9000 (at least with SysInfo). Noting these were quick and dirty preliminary tests and I will be more careful and thorough after the new ROM sockets.

I'm not familiar with the ZZ9000 or if it might affect the floppy drive operation or not.  You wouldn't expect so, but I can't say for sure.

I'd agree with replacing the damaged ROM socket as that can cause future problems.  IC sockets are troublesome at the best of times, more so when they're physically damaged.  Though if the system shows normal signs of life, you should be able to continue with some basic checks on the floppy drive interface.  I'd suggest starting with the latest version of Amiga Test Kit, which you can run directly from the hard drive in order to do the floppy drive tests.  Some people apparently have trouble running ATK from the hard drive, though it's always worked fine for me.  If there are problems running it, I'd suggest trying without startup sequence.

[dingebre]

It's not that generous.  Amiga repairs have been one of my normal jobs for the last 25 years.



I'm not familiar with the ZZ9000 or if it might affect the floppy drive operation or not.  You wouldn't expect so, but I can't say for sure.

I'd agree with replacing the damaged ROM socket as that can cause future problems.  IC sockets are troublesome at the best of times, more so when they're physically damaged.  Though if the system shows normal signs of life, you should be able to continue with some basic checks on the floppy drive interface.  I'd suggest starting with the latest version of Amiga Test Kit, which you can run directly from the hard drive in order to do the floppy drive tests.  Some people apparently have trouble running ATK from the hard drive, though it's always worked fine for me.  If there are problems running it, I'd suggest trying without startup sequence.

Hobby stuff is on hold til next week I'm afraid. Some parts have arrived and I'm waiting on some other stuff. I'll be able to make some time next week to do a careful analysis and some testing.

David

[dingebre]

I think I have the tools now to explore deeper into the motherboard. Got the DiagROMs and serial loop back connector, a scan doubler so I can remove the MTN ZZ9000, new 40 pin sockets, and some spare "custom" chips just in case. I also have some new floppy cables. I haven't dug into the serial terminal communication for the DiagROMs, but I'm hoping I don't need to. I'll go through your suggestions and will first check for a boot screen with no fast memory, discs, or any expansion cards. Then proceed from there.

I also have influenza (edit: COVID, man I still feel horrible) . Thank you to a family member hacking all over the place at the family Christmas Eve party. I should be back at it next week.

David