Atari diag card issue

[rubber_jonnie]

I'd agree with @exxos regarding the 74HC86, if you're not up to speed with surface mount soldering it may get worse.

If you are then that's up to you really.

I would get the board under a microscope on both sides before soldering though to be sure that there is nothing shorted or damaged before you start desoldering items as it may be something physical that is more easily fixed.

Generally speaking an all white screen often means that no ROM is found, and a white border with black screen is a RAM issue just for your information.

Is it possible the owner has installed it upside down? These are simple boards that are tested before dispatch, so it's quite unusual for one to be dead as you describe.

[Badwolf]

???, Don't work, I can't be any clearer than that.
White screen ,no respond.

White screen (and yes, that's more specific) is interesting. That tends to mean ROM isn't executing (as opposed to black screen which usually implicates RAM), a red screen which means the cartridge ROM has signalled error or a blue screen which is it's crashed after initialisaion.

So either the cartridge ROM is being picked up and crashing early, or the physical cartridge is trashing the bus stopping anything working. A bad connection would normally mean you boot to desktop as the magic word, checked early in the boot, is never detected.

What happens if you boot with the cartridge in, but the PLCC ROM removed?

BW

[Giants]

#What happens if you boot with the cartridge in, but the PLCC ROM removed?
Atari boot normaly to Desktop.

Replacing the SMD is no problem.
I already repair all types of Amiga models (500–4000).
I have training in electronics and am equipped to work on SMDs of any size without any issues.
I have extensive experience in this area.

The PCB has already been examined under a microscope, and the PLCC socket has also been checked on all its pins.

Actually, I just had a major doubt about the DIP switch configuration.

I’ve already built and shared projects with the community, such as:
- SMD audio sampler for Amiga
- Amiga repairs (and sometimes a few Ataris, though I find their schematics less clean and practically no two models are alike, LOL)
- Replicas (C64, Amstrad 6128, Amiga 500, 600, 1200, 2000)
- Amiga Repair
- PS4 repair
...
- The list is too long

Anyway, it won’t be a problem to replace this SMD

I will keep inform you when I will receive it.

[Badwolf]

#What happens if you boot with the cartridge in, but the PLCC ROM removed?
Atari boot normaly to Desktop.

Now that's interesting.

So that implies it's either a problem with the content of the ROM chip, the ROM chip itself is making a bad connection in the socket causing crashing or the ROM chip is being active when it shouldn't be.

The first seems unlikely as you've dumped it.

The second is perfectly possible, but then if you've tried all combinations of jumpers the YAARTT setting should not stop the machine booting, even if rubbish is being read off the chip. Can you reconfirm that's the symptom in YAARTT mode?

The third one is possible if one of the components was damaged somehow causing the CE and OE lines to be active when they shouldn't be. Usually that would be all the time if there's been a chip failure. Assuming of course, you've been thorough in ruling out line shorts.

Since you've done so many previous electronics jobs, you probably have a scope to hand. I would suggest probing the CE and OE lines. One should pulse at best or one be constantly high at worst. If both are constantly low, then you probably have got a blown logic chip.

BW