Tracking down TT / ST-RAM errors

[PacificState]

I have a TT which is upgraded to 8MB of ST-RAM - it came with 2MB of SMD chips which I removed with hot air and replaced with higher capacity chips. I'm now struggling with intermittent system errors (two bombs), with YAART's ram test showingan error at 0x0033b12a.

I suspect a pin or two of the soldering is off, but it'd be great to be able to pinpoint the error in case one of the ICs is bad - is there a way to map the address to a chip? Thanks!

[frank.lukas]

Read the posts there ...
https://forum.atari-home.de/index.php/t ... 540.0.html

[PacificState]

Thank-you! I actually noticed that one of the pins at the end of the big custom ASIC on the ram card *somehow* wasn't soldered, and was making intermittent contact. It now seems to be OK having touched it up.

[PacificState]

I now need a bit more help with a reset issue! I'm finding that which the machine is now stable when booted, after leaving the it powered down for some time, the TT fails to start when turning on the power switch - there's a single click from the speaker, but the screen stays black. Furthermore, reset doesn't help at all and I have to turn the switch off and on again - after which it will start up OK (with two clicks audible from the speaker).

Couple of things:

- The machine has 10MB of ST RAM, along with Thunder, Storm, and Lightning boards

- I've replaced the two 10uF reset capacitors, with no apparent effect

I have a scope, but I'm not sure where to start. However, it makes me wonder if it could be PSU related. Any ideas? Thanks in advance!

[frank.lukas]

Check the PowerGood Line ...

... on the PowerSupply and on the Mainboard, see the schematics.

[mikro]

I would definitely start with stripping the machine off to the bare PCB - 2 MB ST RAM and nothing else.