My A4000 is slowly dying?

[mfletcher]

Hi,

Ive noticed that 20% of the time when my A4000 boots, the display can be a little bit garbled, with horizontal lines running down the screen. Shutting it down and restarting it solves this. Im 100% sure that it is not the monitor as I use the same monitor with my Mac Pro all the time and I have not seen this issue occur.

Im wondering if this is a sign that my A4000 is slowly failing. Is there any diagnostics I can run to check this, or is there any way that this can be fixed short of getting a new motherboard?

Thanks,

Mark

[rkauer]

Hi,

Ive noticed that 20% of the time when my A4000 boots, the display can be a little bit garbled, with horizontal lines running down the screen. Shutting it down and restarting it solves this. Im 100% sure that it is not the monitor as I use the same monitor with my Mac Pro all the time and I have not seen this issue occur.

Im wondering if this is a sign that my A4000 is slowly failing. Is there any diagnostics I can run to check this, or is there any way that this can be fixed short of getting a new motherboard?

Thanks,

Mark

Just swap the electrolytic caps in the main board and PSU and you will see a shine, steady picture. And no GURU 's, of course.

Those SMD caps (as the regular ones, too), have a lifetime of 15~20 years, top.

Replace 'em and be happy again.:D

[mfletcher]

Heres an example of what Im seeing: Heres a "good" screen.

http://www.markfletcher.org/amiga/dscf0005.jpg

And heres an example of a bad screenhttp://www.markfletcher.org/amiga/dscf0004.jpg

I think the vertical banding is due to the converter that Im using, but the corruption of the text in the bad image i cant explain.

Mark

[rkauer]

--snip--
I think the vertical banding is due to the converter that Im using, but the corruption of the text in the bad image i cant explain.
Mark


That misbehaving is explained by the near-the-end capacitors. When they heat a bit, they start to act like a "normal" one. But they aren't.:blased

Electrolytic capacitors dry as the years passing. That's why I told you to swap 'em ASAP.

[Jope]

The banding is because your converter's output resolution is not the same as the TFTs native resolution.

The corruption looks like it's doing deinterlacing but has the fields in the wrong order.

To solve the banding, get a converter that outputs the same resolution as is the TFTs native, to solve the corruption, try and power cycle the converter, perhaps it'll resync.

[mfletcher]

An external scandoubler arrived at the beginning of this week - I suppose I could try that and see if htat fixes the problem.

[Jope]

The banding problem probably won't go away, but the garbling problem should be solved.

[mfletcher]

I fired up the A4000 tonight with the external scandoubler flicker fixer.

One thing I tried was checking the boot screen (insert disk prompt), by unplugging the HD cable. Repeated this about 10 times - no garbling / corruption problem was noticed. Spurred on by this I then tried just booting up to WB 3.1 using the WB 3.1 floppy. Again, repeated this about 10 times, no trouble found.

Finally tried plugging back in the HD cable and booting up off the HD. Display came up fine first time. But when I rebooted, I saw the garbling / corruption issue. Im thinking at this time, its the OS on the HD, OS 3.9. Just to make sure, I rebooted a few more times to the WB 3.1 floppy and no troubles found.

I cant explain why I see this kind of behaviour in OS 3.9 (I dont know enough about it), but Im beginning to think the best thing might be to wipe the drive and go back to something like WB classic...

[coze]

is there a difference between the screenmode used by 3.9 and 3.1 floppy ?