A1200 won't boot - keeps rebooting

[kixs]

Hi there,

I have this problem with my A1200. The last time I used it, about a month ago, everything was OK. Then I moved to another flat and today I wanted to setup my computer desk.

Connected everything and turned the power on. It looks like it's in rebooting loop. The gray screen is for about 4 seconds then screen lightly blinks and again gray screen for 4 seconds and this on and on. It doesn't come to read the floopy.

I already disconnected the HDD and memory expansion board. Holding the two mouse buttons does nothing.

Any ideas?

Thanks!

[AlfaRomeo]

Hi kixs,

the first thing to do it´s open your A1200 and, gently, get rom chips out from their support and put them again to prevent bad contacts. Next inspect your mobo around capacitors to see if they hadn´t dropped any acid. If it´s wet around caps you has to clean it, if not, close your A1200 again and test it to see if it works again.

[kixs]

Did as you said, reinserted ROM chips. Capacitors look good. Still no progress as it reboots as before.

If I disconnect keyboard, floppy and HDD is it supposed to boot to the insert floppy screen or what happens in this case?

Any other ideas I should/could try?

Thanks

[FOL]

Originally Posted by kixs

Did as you said, reinserted ROM chips. Capacitors look good. Still no progress as it reboots as before.

If I disconnect keyboard, floppy and HDD is it supposed to boot to the insert floppy screen or what happens in this case?

Any other ideas I should/could try?

Thanks

If you have Kickstart 3.0, it will take about 10 seconds to show kick screen.
If you have Kickstart 3.1, it will take about 40 seconds to show kick screen.

[DH]

Not much help but check the screen colours here may help a little to as what's the problem http://eab.abime.net/showthread.php?t=20302

[prowler]

Originally Posted by DemonHellraiser

Not much help but check the screen colours here may help a little to as what's the problem http://eab.abime.net/showthread.php?t=20302

Originally Posted by kixs

Connected everything and turned the power on. It looks like it's in rebooting loop. The gray screen is for about 4 seconds then screen lightly blinks and again gray screen for 4 seconds and this on and on. It doesn't come to read the floopy.

Well, according to that thread, the colour gray indicates that the hardware, registers and software checks are satisfactory and the light blink (white?) indicates that the system is ready to boot (at least for an instant)... but then it reboots!

So the problem doesn't sound too serious: the initial checks are successful and the system is just getting ready to boot - when something triggers a reboot.

I am inclined to suspect the power supply.

[kixs]

Kickstart is V3.0 (39.106)

I have one other Amiga 1200 and that one works with the same power supply just fine.

About the boot colors, I checked that thread before thats why I described the reboot process in colors. That blink after 4s is just that - it just blinks kinda black but really fast - Amiga is connected to an LCD monitor and then it looks like this is doing repeatedly nonstop.

[Angus]

Originally Posted by kixs

Did as you said, reinserted ROM chips. Capacitors look good. Still no progress as it reboots as before.

If I disconnect keyboard, floppy and HDD is it supposed to boot to the insert floppy screen or what happens in this case?

Any other ideas I should/could try?

Thanks

What progress did you make disconnecting peripherals, Kixs?

I would think taking it gradually back to vanilla and seeing at what point it boots properly would be informative.

For some reason I'm wondering about the hard drive cable and its connection.

[kixs]

Right now everything is disconnected and the problem remains as described in post #1.

[rkauer]

Time to start replacing the capacitors and checking if one of the little SMD resistors din't break apart.

Patience, calm, a good light source and a magnifier can make things happen. Of course, better just replace the capacitors and the SMD 555 in the board before checking the hundreds of resistors on it.

[kixs]

I guess I'll have to make some time this weekend and replace at least the non SMD capacitors and the SMD 555 as you said.

thanks

[kixs]

Just replaced all the non-SMD caps and the problem stays, no improvement whatsoever.

On a closer look I think the C459 SMD and E232R look kinda suspicious. Does anyone know if these two could be in someway related to the problem?

One other thing... Even before this the signal from composite out was very bad with lots of interference - this hasn't changed.

Hopefully someone can make something out of this.

Thanks

[AlfaRomeo]

If I was you would replace all smd caps. If you utilize the rkauer´s technics (two solder irons)to desolder smd caps it´s very easy. To solder the caps again you can utilize standard caps as it´s is more easy to solder and still do the same effect

[kixs]

Probably the best idea, 'couse I can't get the required SMD caps.

[AlfaRomeo]

Originally Posted by kixs

Probably the best idea, 'couse I can't get the required SMD caps.

yeah I did that with my A600 caps because despite I can get the required SMD caps some of them are larger than the originals and didn´t fit in the original place.
In standard caps I cut their legs so keep about 1cm of the legs, then I bend the final 2mm of each leg in 90 degrees and solder these 2mm of each leg in the original place.
Keep in mind that the caps are polarized, the minus signal of caps leg fits in oposite of + sign drawn in the original places

[rkauer]

Before do some radical thing like replacing discrete capacitors, look close to other places that can affect the motherboard behaviour, like cold joints.

Special attention must be paid for the power connector and those ferrite coils right on the Amiga left side.