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Old 12 February 2019, 20:20   #1
Amaris
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Amiga 1200 Start-Up problems. Probably hardware damage

Hi @all,


I'm new here and I have some serious problem with my A1200. I will give a quite extensive description of the problem and what I have done already to solve it. So, prepare for a longer text ;-) BTW, English isn't my native language.



I bought this A1200 sometime around the year 2002 AFAIR. In about 2005 I put it in an Infinitiv tower case. Unfortunately this A1200 has had always troubles to start up. Often it would take 6-7 times switching it on and off until it finally booted up. It often did simply nothing. No reaction whatsoever. But after switching it on and of, finally it booted up at some time.


The configuration was and is:
A1200 with Elbox Mediator 1200 LT4 busboard
Blizzard 1260 Turbo car
CD-ROM drive
1 GB, 2,5" HDD

This was until about two weeks ago - when I decided to put it from the Infinitiv tower to a new "Elbox Black Box 1200" tower.

But since then, the Amiga is almost(!) dead. I don't know what made the start up problems so much worse.

The symptoms are as follows:

1. If you take the "naked" A1200 mainboard with no turbocard, no CD-ROM drive, but only disk drive and no hard disk - then it takes about 20 seconds to show the startup screen with the hand and disk

2. If you connect the CD-ROM drive additionaly to this, it boots to the "hand screen" instantly, with no delay whatsoever.

3. If you remove only the +12V cable from the CD-ROM drive, you are back to state 1.

4. If you connect the hard disk, the A1200 will not start up at all. No reaction. Nothing, besides an undefined black monitor signal.

5. If you connect the Blizzard 1260 card, you are also in state 4. No reaction

6. If you connect a Blizzard 1230 III card, which I also own, the Amiga started up a few times to the "hand screen" after 20 seconds. But after a few times failed to do so and then remained this way. Now the 1230 has the same effect as the 1260.

7. If you remove the disk drive, but connect the CD-ROM, then it boots to the hand screen after about 5 seconds.

I think the pattern here is quite obvious. Disk drive and CD-ROM have their own voltage connections of +12V. Contrary to that the 2,5" HDD and the turbo cards have not, but get their power from the mainboard. The first two devices "help" to boot up, while the others make it impossible.

There's some voltage issue behind this, I believe.

Well...in my "despair" I tried to replace all electrolytic capacitors. I replaced most of them. A few weren't in stock by my local dealer and I should get them in a few days.
But it helped nothing, so far. The Amiga still behaves exactly as before.

There is one additional important thing, I should mention.
This Amiga was definitely damaged before. I discovered that the ferrit bead, which is connected to Pin 23 of the video port is destroyed. Some previous owner bridged it with a fuse! It works, but seems a strange way to repair that. But this indicates that this mainboard was already damaged somehow, a long time ago.

I suspect that these issues are somehow connected, but I don't know what part could have been damaged in addition to the ferrit bead, which could cause my problems.

Yeah...that's it, so far.

If anyone would have any hint, what to do or where to look, I would be very grateful.


Sincerely,
Amaris
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Old 12 February 2019, 22:49   #2
utri007
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OK, I'm quite sure that I know what at least partially is reason for you problems.

I have infinitiv tower and Zorro extender and it used to have same problems.

A1200 mobo is power through mediator? If so problem is solved inserting more power to A1200. I used to have wires from PSU to A1200's floppy's power port, I know many people did this old days. Now i have soldered wires to place of original A1200 power connector, so that there is two power connectors, one for bus board and one for A1200. Works rock solid.
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Old 13 February 2019, 17:45   #3
Amaris
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Hi, thanks for your answer!



Quote:
Originally Posted by utri007 View Post

A1200 mobo is power through mediator? If so problem is solved inserting more power to A1200.



Well, usually it is powered through the mediator. But I tried it with the original Amiga PSU, too.
That means: Naked A1200 board, no mediator, no CD-ROM or anything. Same result. As soon as I connect a turbo card or HDD, the computer is dead.


Maybe you method would work. But I think it would be a workaround, at best. No real solution.


And the important point is - this problem didn't exist before I removed it from the Infinitiv tower. At least not in that severe form. The computer did start with turbo card & HDD. Now one of them alone is enough to prevent it from starting.
Something has made the previous problems much worse.
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Old 13 February 2019, 18:31   #4
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Can you measure the voltage on the 5V line? If you're careful, it can be measured at the IDE port, but otherwise at the floppy power connector.

Steps 1-3 are normal behaviour. It's very odd that a different drive would prevent it from booting if it had worked fine before, unless there is a power issue. If there's perhaps a partial short somewhere, you might already have a lower than normal 5V rail, and the extra drive is just enough to drop it too low to start the machine.
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Old 13 February 2019, 20:29   #5
Lord Aga
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Maybe try a CF card instead of an old n clunky hard drive?
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Old 13 February 2019, 20:48   #6
Amaris
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Quote:
Originally Posted by Daedalus View Post
Can you measure the voltage on the 5V line? If you're careful, it can be measured at the IDE port, but otherwise at the floppy power connector.

Okay, I tried it with both PSU's. The external Amiga-PSU and the ATX-PSU from the BlackBox1200 tower. With both I measured about 5.13V at Pin 41 of the IDE port, without any turbo card or HDD. And about 5.09V with either of my two turbo cards.
That is, there is obviously a small voltage drop at this point of the mainboard, but I'm not sure if this is relevant or not. My knowledge of electronics is too basic to judge that.



Quote:
Steps 1-3 are normal behaviour.
They are?

I read about that boot delay for HDD's with Kick 3.1. But how is this connected to the CD-ROM drive?



Quote:
It's very odd that a different drive would prevent it from booting if it had worked fine before, unless there is a power issue.
Well, I use a 2,5" HDD, which has no seperate power connection to the PSU like a CD-ROM drive or 3,5" HDD has.



Quote:
If there's perhaps a partial short somewhere, you might already have a lower than normal 5V rail, and the extra drive is just enough to drop it too low to start the machine.
That was my suspection as well, yes.



Quote:
Originally Posted by Lord Aga View Post
Maybe try a CF card instead of an old n clunky hard drive?

No, that's not an option. First, the turbo cards have the same effect as the hard drive. I would be permanently unable to use turbo cards.


And second, there is obviously something wrong with this mainboard. I think the right way is to search for the problem, not circumvent it. Actually I lived about 15 years with an unstable Amiga and now that it's gotten much worse, I finally want to solve the problem.
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Old 13 February 2019, 20:53   #7
Lord Aga
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Quote:
Originally Posted by Amaris View Post
No, that's not an option. First, the turbo cards have the same effect as the hard drive. I would be permanently unable to use turbo cards.

And second, there is obviously something wrong with this mainboard. I think the right way is to search for the problem, not circumvent it. Actually I lived about 15 years with an unstable Amiga and now that it's gotten much worse, I finally want to solve the problem.
But it would help you with diagnostic. CF cards use less power. So if it works, it very well may indicate a power problem.

That old hard drive probably uses a WWII submarine engine motor drawing 10KW at startup. It is wise to get rid of it entirely and even when everything is fixed stick with the CF card.
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Old 13 February 2019, 21:15   #8
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Quote:
Originally Posted by Amaris View Post
With both I measured about 5.13V at Pin 41 of the IDE port, without any turbo card or HDD. And about 5.09V with either of my two turbo cards.
That is, there is obviously a small voltage drop at this point of the mainboard, but I'm not sure if this is relevant or not. My knowledge of electronics is too basic to judge that.
No, there's nothing wrong with those levels. A small drop is fine, but if it was down around 4.8 I'd say that was your problem. But at least it's ruled out an undervoltage issue.

Quote:
They are?

I read about that boot delay for HDD's with Kick 3.1. But how is this connected to the CD-ROM drive?
Yep. The delay in 3.1 is to allow slow drives to spin up, which sometimes caused issues with not being detected under 3.0. But the delay is cancelled as soon as the hard drive responds, which is usually a second or two after power up, so you don't sit waiting when the drive is ready. A CD-ROM drive doesn't have such a spin-up and so responds immediately, causing the delay to be cut to a fraction of a second.

Quote:
Well, I use a 2,5" HDD, which has no seperate power connection to the PSU like a CD-ROM drive or 3,5" HDD has.
Indeed, it was the only theory I had, that the 5V requirement was the difference that stopped it booting. So I'm kinda stumped now.
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Old 13 February 2019, 22:51   #9
Amaris
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Quote:
Originally Posted by Lord Aga View Post
But it would help you with diagnostic. CF cards use less power. So if it works, it very well may indicate a power problem.

Hmm...I think that the symptoms indicate a power problem, already. Since it boots up and e.g. loads the Workbench from a floppy disk without problems, if no HDD is connected (and no turbo card).
I don't think that more can be learned about the problem by using a CF card. If only the HDD would cause the problem, I would say you are right and let's try a CF card. But the turbo cards have the same effect!

Still, I appreciate your advice and....

Quote:
That old hard drive probably uses a WWII submarine engine motor drawing 10KW at startup. It is wise to get rid of it entirely and even when everything is fixed stick with the CF card.
...this is surely true
If this problem is solved, maybe I will get one.


Quote:
Originally Posted by Daedalus View Post
A CD-ROM drive doesn't have such a spin-up and so responds immediately, causing the delay to be cut to a fraction of a second.

Ah, I see. That was my suspection.


Quote:
Indeed, it was the only theory I had, that the 5V requirement was the difference that stopped it booting. So I'm kinda stumped now.
Me too. But somehow...I still think there must be an undervoltage at some point of the board. All indicators point to it, I would say.


There something I didn't mention, yet. But I don't know if anything can be learned from it.

If you connect the HDD and the CD-ROM. Then it doesn't boot up, like I said. But if you then pull the HDD from the cable (while the Amiga is running and showing an almost black screen), it boots up instantly. I wonder what is happening, just when you pull it. If one could find this out, it would surely point directly to the cause of the problem.


Probably the same thing would happen if you pull a connected turbo card. But I didn't dare to do this.


There's another thing: When I measured the voltages today and the 1230 turbo card was connected - it did more than nothing, this time. There were some flickering horizontal red lines, then the same screen as during the boot delay (waiting for HDD spin up), then red lines again and so on. After a while then, I got a yellow screen, which means the CPU encountered some error.

http://wiki.classicamiga.com/Amiga_b...r_code_colours


The 1260 card did nothing, as usual.
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