Megachip woes

[KatManDEW]

Is the attached image the correct way to install a Megachip? Installed this way, the Fat Lady is oriented the same way she is oriented without the Megachip board, but I have no video with the Megachip installed.

When I reinstall my original Fat Lady, I have video again.

[Fingers]

http://amiga.resource.cx/manual/MegAChip.pdf

PZ.

[orb85750]

The orientation looks correct.  And your jumper is connected properly to Gary?

[Fingers]

*edit*

That's an A3000 Agnus in there.

Are they compatible with the MegAChip? I'd imagine so, but you never know.

Did you check/modify your motherboard revision as per the manual?

PZ.

[KatManDEW]

Thanks for all the replys!

I had a printout of the PDF file laying beside my Miggy while installing the Megachip, but the PDF instructions were confusing as for the orientation. The PDF said "To install the MegAChip 2000/500™ in your computer you need to hold the board with the Agnus chip facing you and in the same orientation as it was in the computer. Holding the MegAChip 2000/500™ in your hand by the edge of the board, the adaptor plug on the MegAChip 2000/500™ should be to the left over the Agnus socket with the memory chips on the MegAChip 2000/500
™ to the right."

They didn't mention which way the motherboatd should be facing....

[KatManDEW]

According to the PDF instrustions, I didn't need to modify my motherboard because I already had 1 meg of chip RAM (I think I made the modifications many many years ago, when I upgraded from 512k to 1 meg).

The PDF instructions say "Part number 318069-11 is for NTSC use and part number 318069-10 is for PAL operation."

My chip is 318069-19. Some info I read on The Big Book of Amiga Hardware said the Megachip allowed using a A3000 Agnus...

I got the Megachip from SoftHut, and they originally sent me a "MegIchip", without any jumper wires, and I only had 512k of chip RAM with it installed. They sent me the current MegAchip as a replacement, but the jumper wire was broken off and I had to solder it back on.

I just checked the MegIchip that they sent me, and it has a 318069-11 on it. Maybe I chould try that chip in the MegAchip?

[Damion]

You got the orientation right.

I just checked the MegIchip that they sent me, and it has a 318069-11 on it. Maybe I chould try that chip in the MegAchip?

I think your problem is the Agnus revision in the MegaChip, it should work fine with the the "-11" part (it's what's in mine). Is your other one a DCE MegiChip? Most (all?) of those had the Agnus soldered on. :/

*edit* they must have sent you one of these? In which case you're golden, swap the Agnus and I bet it works.

[KatManDEW]

The first one they sent me has the Agnus soldered on  :boohoo: But it doesn't have the "jumper socket" to go under the Gary chip :madashell:

[Fingers]

Soldering time! 8-)

PZ.

[Damion]

Fingers wrote:
Soldering time! 8-)

PZ.

Yeah, I would get a socket and solder the wires (good pics of where they go on amiga resource). Kind of a PITA, but with the correct 8375 Agnus (NTSC versions are somewhat easy to find) and your MegIChip fixed, you'll have two working units. :-)

[KatManDEW]

Any reason I couldn't just two jumper wires with the MegIchip, instead of the Gary "jumper socket"?

[alexh]

Fingers wrote:
That's an A3000 Agnus in there.

It is an Agnus which has been spotted in an A3000. It is not necessarily an A3000 specific Agnus. No-one has been able to successfully work out what, why, where all the different versions mean (other than where they have seen them in use)

MegAchips were designed to take different Agnus chips depending on how the PCB was wired up (resistors, zero ohm links etc.) so DKB could use which ever Agnus was cheaper that week.

If that MegAchip came from the manufacturer with the -19 chip then it was designed to use that chip.

[Damion]

KatManDEW wrote:
Any reason I couldn't just two jumper wires with the MegIchip, instead of the Gary "jumper socket"?

None at all, that would work fine.

[KatManDEW]

[/quote]

Yeah, I would get a socket and solder the wires (good pics of where they go on amiga resource). Kind of a PITA, but with the correct 8375 Agnus (NTSC versions are somewhat easy to find) and your MegIChip fixed, you'll have two working units. :-)
[/quote]

Thanks again for the info.

I would settle for one that works :boohoo:

Where would I find a NTSC 8375 Agnus?

[KatManDEW]

None of the MegIchip photos look like mine, so I'm not sure which wire goes to which pin on the Gary chip?