Diagnostic cartridge issues MSTE

[exxos]

Now the question is, how do I find a replacement for this component, and do you think it's safe to temporarily "shunt" it with a wire to see if that fixes the issue?

You can just wire link over it, but of course if you short out something out on the cartridge port, it could vaporise the PCB traces on the 5V to it..

If you have any sort of <1A fast blow fuse that would be better... Or even something like a 1/4 watt <10R resistor would be at least some safety.

[Dbug]

And we have a winner \o/

image_2021-09-24_181536.png

Damn you F21!

image_2021-09-24_181549.png

So I guess the fuse must have partially blown, may some static discharge, making the expansion bus to not be working as expected.

Now the question is: Could this also have impacted other things?

[exxos]

So I guess the fuse must have partially blown, may some static discharge, making the expansion bus to not be working as expected.

Now the question is: Could this also have impacted other things?

While I have seen fuses do odd things in the past, is probable that the "5V" supplied by the address/dataline via the ROM. It's why I always say cutting the power to chip does not disable it, because it can be powered via its IO lines.. So I assume this is what you are seeing rather than a "iffy fuse".

[Dbug]

I guess to replace F21 I need something that is 0.5 amp, small enough to fit, and with pins so it can be soldered.

Would this type of fuse work?

https://no.rs-online.com/web/c/fuses-so ... 4294574006

I checked the Service Manual but could not find a reference for this fuse, if anyone can think of a proper replacement, please share :)

[exxos]

You just want a Axial quick blow 0.5A fuse..

I really would avoid those resettable ones.. Things tend to catch fire and explode by the time they have tripped.

[Dbug]

You just want a Axial quick blow 0.5A fuse..

I really would avoid those resettable ones.. Things tend to catch fire and explode by the time they have tripped.

Ouch, that sounds bad!

Would any of these work? (In Norway I'm somewhat restricted to what I can get fast or a decent prices)
https://no.rs-online.com/web/c/fuses-so ... 4294583822

So, I continued my investigation, and after doing this fuse shunt, I actually managed to get the MonSTer card working *with the blitter*, so the machine correctly reports 4 megs of ST ram and 6 megs of ALT ram, which is good.

What's less good, is that with or without the MonSTer, my VME cards (I have a Spektrum 1 (the 256 colors model) and a Nova (with a ATI Mach32 card)), and they don't work, when I run the diagnostic cartridge it tells me "No vme board found in system".

How should I troubleshot that? Are there any "usual suspects"?

Thanks again for the help so far :D

[Steve]

What's less good, is that with or without the MonSTer, my VME cards (I have a Spektrum 1 (the 256 colors model) and a Nova (with a ATI Mach32 card)), and they don't work, when I run the diagnostic cartridge it tells me "No vme board found in system".

How should I troubleshot that? Are there any "usual suspects"?

Thanks again for the help so far :D

You'll find the VME bus schematics on page 9 here: https://exxosforum.co.uk/downloads/MegaS ... 4_1992.pdf

It's definitely not something simple to diagnose... but I would start with making sure your cards are receiving the correct voltages first, just like with your cart problem. Also make sure on the Nova that it is set to MSTE, I know they have a jumper for TT/MSTE.

@frank.lukas has probably the most experience with VME, perhaps he might have some ideas too.

[frank.lukas]

Diagnostic Cartridge for Atari TT and Mega STE with the VME Test need a spezial VME Bus Ramcard with 1MB Ram I think. See the Service Manual for the Diagnostic Stuff ...


https://exxosforum.co.uk/atari/mirror/go ... GA_STE.pdf

page 21

[Dbug]

Diagnostic Cartridge for Atari TT and Mega STE with the VME Test need a spezial VME Bus Ramcard with 1MB Ram I think. See the Service Manual for the Diagnostic Stuff ...


https://exxosforum.co.uk/atari/mirror/go ... GA_STE.pdf

page 21

Haaa, did not know that.
So the Spektrum card may be working, just that the diagnostic cartridge does not know about it.

Thanks.

[Dbug]

Well, I guess I got it working.

Too bad my Spektrum card seems dead :-/