4mb STFM SMD Ram upgrade - FAILS TO BOOT :(

[Lurch]

I have (had!) A fully working 520 STFM C070789-001 Rev:F2 board.

I've done the lastest SMD 4mb ram upgrade on it, plugged everything back in (NOT assembled) and........

Yellow border and black paper screen is all i get - no beeps, just that image.

ANYone know something from the above screen colours that would point to the fault?

Thanks

[PhilC]

Hi @Lurch the black foreground is usually a sign of a memory issue, so id investigate that first.

[DoG]

Have you desoldered the old ram or deactivate the old onboard ram? Check and recheck everything you have done. Most likely a bad connection or some bridge somewhere.

Please provide photos of the board and fitting of the connections if you can. That is easier for all of us to spot anything out of the ordinary.

[Lurch]

Hi Folks,
Thanks for the answers - I've gone over each solder point for the board and cannot see anything bridged

I added the 3 Resistors as mentioned at 68R - however the others in the board are a different level!

So, here is A picture of the screen output now, and a closeup of the resistors

(I removed ALL the ram IC's from the board)

Output AFTER ram upgrade

Atari_Screen.JPG (271.19 KiB) Viewed 4520 times

PResistors are a different value to others populating the board

Atari_Res.JPG (338.88 KiB) Viewed 4520 times

[exxos]

Have you wired up the 4MB wire ? You may want to remove it in case its in the wrong place.

[Lurch]

Have you wired up the 4MB wire ? You may want to remove it in case its in the wrong place.

The wire going to A9 you mean?

[exxos]

The wire going to A9 you mean?

Yes... Well its MAD9 not A9.

[Lurch]

The wire going to A9 you mean?

Yes... Well its MAD9 not A9.

I can just unsolder the Ram board side, or would you say remove from the MMU?

Those resistors ok too?

Just thought they all should have been the same value?

[exxos]

I think your over thinking all this. I only suggest you just unsolder the wire, from the RAM PCB is fine, to see if 1MB RAM works... That's all.

You likely have a bad solder joint somewhere. So I would suggest you check all your soldering. If it still doesn't work then you really need a diagnostic cartridge to diagnose where the faults are.

It looks like you have 68R resistors in there.. 33R is better. But again removing the wire will help diagnose.

[Lurch]

Thanks, I'll give it a try in the morning - unsoldering the switch wouldnt help test it?

Again, thanks for your help