A2000 GVP or Mega Chip Problem

[gertsy]

I have an A2000 rev 6.4, GVP 040 Combo w 16Mb, Mega Chip 2000 2Mb, & A2320.  Randomly on startup both the 16Mb and Mega Chip will drop out. After a few reboots they will come back. Either both out or both available, never one or the other.
Repositioning seems to fix on the next startup but the problem will happen again on a random following reboot.
I've never had a dropout while active.
I thought power supply but basic volt checking on startup shows 11.88v and 4.9v on 12 & 5v supply.

N E 1 else had a simular issue ?

[gertsy]

Bump. No thoughts ?

[Xanxi]

I would double check a bad contact issue with the Mega Chip. Do you get green screens?

[Gilloo]

Bump. No thoughts ?

Similar to what happens to my B2000 4.4, with external 4MB card, the megachip was present or make a blank or a green screen.

Take a white eraser and clean Agnus chip and megachip contacts... (not the socket)
Check the wire and the grip...
Clean also the cards connectors with the eraser.
Remove all shavings

Never occurs since this cleanup.
Otherwise, check capacitors shape on the motherboard... perhaps it's time to change them...

[gertsy]

Cheers Gilloo.  Capacitors looked okay last checked 18 months ago, no swelling, yellow stains, or dust gathering.
Will clean the megachip contacts.  I remember they did look a bit agricultural.
It's a bit of a job getting in there, but, must be done.  The old girls need TLC.

[save2600]

What kind of shape is the lead that connects from the MegaChip to pin #36 of Gary in? Good solid connection there?

[orcish75]

Do you still have your original Agnus lying around? If so, remove the Megachip and replace it with the original Agnus. At least then you've eliminated any fault with the Megachip, the wire connecting Gary, the RAM, PAL etc..

I had a problem with my Megachip and my A2286 bridgeboard. The bridgeboard would intermittently freeze and then get a Green Screen of Death. It was the wire connecting to Gary that had broken within the plastic sheath and was losing connection as soon as the cable warmed up a touch.

[gertsy]

Do you still have your original Agnus lying around? If so, remove the Megachip and replace it with the original Agnus. At least then you've eliminated any fault with the Megachip, the wire connecting Gary, the RAM, PAL etc..

I had a problem with my Megachip and my A2286 bridgeboard. The bridgeboard would intermittently freeze and then get a Green Screen of Death. It was the wire connecting to Gary that had broken within the plastic sheath and was losing connection as soon as the cable warmed up a touch.

Interesting.
Well I took everything apart, cleaned all the contacts on the Agnus socket in the a2000 and the pins on the Megachip re-ran the connector to the Gary chip I thought I'd fixed it but on a cold start today same problem. 2 MB of chip ram drops to 1MB and my 16MB on the GVP disappears.  Also the machine is very sluggish WB wise. I fired up Sysinfo and it said my 040 was there but when I ran a speed test it posted A600 speeds.
 Once it is warmed up if I turn it on it comes back.  Maybe I have the opposite problem the wire loses contact when it is cold but once warmed up...?

BTW: I have a PAL A2000 6.4Motherboard but my Agnus is NTSC but seems to display the PAL screenmodes fine. I think its an 8372B.

I'll test the Gary wire continuity while cold.

[orcish75]

Is the Agnus on the the Megachip board soldered on or is it in a socket? If it's in a socket, try taking it out and reseating it. Also check all the pins of the Megachip board plug that plugs into the Agnus socket on the mobo.

One of the pins may have detached from the solder pad on the Megachip board after being unplugged and plugged back in a few times. You'll probably have to check it with a magnifying glass as the break may be too small to see with the naked eye.

Also check all the solder connections of the RAM chips and the GAL/PAL.

[kronuz]

Got my megachip today....only getting green static or blinking screen or white and grey alternating screens :/