DKB Cobra reboot issue - caused by overheating?

[mingle]

Hi,

Yesterday my DKB Cobra 40MHz starting behaving is a slightly worrying manner, for no apparent reason:

When I performed a warm boot (CTRL-AMIGA-AMIGA) the system woudl start to reset (the green power LED would dim) but then nothing, just a blank screen.

Then I turned the power off (cold boot) and the same thing.

I had to power off and unplug the PSU for about 30 seconds before I could get it to power up. But I still had the same warm boot issue. Somethime I could get a warm-boot if I held the CTRL-AMIGA-AMIGA keys down for around 5-10 seconds.

The only thing  can think of is perhaps the board/CPU was overheating, since it was around 10-15 degrees C hotter yesterday. Or possibly the (weedy!) 22W A1200 PSU was also feeling the heat?

Does this sound possible?

Cheers,

Mike.

[mingle]

Hi,

Yeah, I tried all of the obvious things first.

Without the Cobra card installed the system seems to be fine, so the issue must be either a fault with the card or the PSU being too weak to drive it.

But it was working fine prior to yesterday - the only difference I can see is that it was a hot day (inside and out!).

Can heat affect the power supply?

Cheers,

Mike.

[mingle]

Hi Az,

Thanks for the info...

The PSU didn't feel particularly hot, but it is one of teh really wimpy 22W ones. I have the DKB Cobra (40MHz) plus 16MB of RAM, plus the Ferret SCSI adaptor and an IBM 4GB HDD - does this sound a bit much?

It's a pretty warm one again today and the A1200's been misbehaving a  bit again.

The CPU on the Cobra card was too hot to touch, but this may be normal, I don't know...

I might have a go at rigging up an old ATX power supply to give it some more juice...

Cheers,

Mike.

[mingle]

Luckily (?) mine is a late Escom A1200, so hopefully it'll be okay for a while longer!

@Az,

Do you have any pics or more detailed info on the heatsinks and how you go about selecting/fitting them?

When you say hotmelt glue, do you mean using those glueguns that take the hard glue-sticks? Does that stand up to the heat generated by the ICs?

Cheers,

Mike.

[mingle]

Hi All,

Thanks for the many and varied comments and suggestions! :-)

Today (about 15 degrees cooler than yesterday!) it's been a bit better.

I've still to muck around with the PSU (converting an old PC PSU) to confirm it's at fault...

The only issue seems to be rebooting - once it's up the A1200/Cobra will run fine without any issues (touch wood!) apart from the CPU getting very warm...

I've always found DKB stuff to be very good - the documentation with the Cobra is admittedly pretty poor, but my old DKB1202 RAM/clock card was very well made and came with great documentation.

Cheers,

Mike.

[mingle]

Hi All,

The ongoing saga with my A1200 & DKB Cobra 030 card:

It doesn't appear to be the PSU, since I've tried two different A500 35W units and it's still misbehaving.

The funny thing is that if the A1200 resets due to a software failure, it will ALWAYS restart without any issues.

It's only when I do a CTRL-AMIGA-AMIGA reset that the reboot seems to stall.

I've also discovered that if I do multiple key presses (CTRL-AMIGA-AMIGA) that will sometimes make it reboot, without having to power it down.

It's still bloody annoying that I have to press and press and PRESS to do a warm boot!

The card will run fine, there's no problem there, it's just it seems to randomly refuse to do a warm boot when I want it to...

Has anyone heard of this type of issue before and is there a solution? Is the reset signal somehow not reliably getting through to the CPU on the Cobra card?

Cheers,

Mike.