Dual Tos Fast switcher...

[DoG]

On the motherboard. To the right of the roms. W102, W103 and W104 should all be linked 2-3. Middle-Right

ste_pcb.gif

[rubber_jonnie]

Jumper links???

Here is a photo of mine:

Jumpers.jpg

What you'll likely have rather than jumpers, are zero ohm links, which look like this:

zero.jpeg

However you can see clearly from the picture the position that the jumpers are in, with pins 2-3 connected.

If you are desoldering the zero ohm links, then I'd suggest you may as well also install jumpers as I have.

BTW, is it just the TOS switcher you have installed at present, or have you also installed the booster too?

[Shugs81]

Booster too... Hope it is the jumpers!! Shame I've got to wait till I finish work to mess about...

[Shugs81]

Oh arse... I've just realised it worked with just the dual tos in it...

I've buggered the booster... Meh...

[rubber_jonnie]

Oh arse... I've just realised it worked with just the dual tos in it...

I've buggered the booster... Meh...

I wouldn't decide it's the booster just yet.

Make sure the TOS switcher is correctly seated if in sockets, you may even want to eliminate it by putting the original 2 ROM set back in whilst you're troubleshooting, it will eliminate one component from the investigation.

Take your time and flux/resolder the connections, check all the wires are correctly connected, buzz them out if you need to, check the CPU is fitted in the correct orientation, make sure that there are no solder whiskers causing shorts (Magnifying glass essential) and to begin with, run it in 8Mhz mode to make sure it runs as a normal STE.

[Shugs81]

Just a thought... If I've put the wires on for switches... But no switches... will that cause issues?

[rubber_jonnie]

Just a thought... If I've put the wires on for switches... But no switches... will that cause issues?

Depends what the end of the wires are touching. Just put on some insulating tape on the loose ends of the wires, so they can't touch anything, and test at 8Mhz before you move on. If it won't work at 8Mhz, then it won't at 32Mhz, so you need to run down what the problem is first.

Do you have any photos of the booster installation, so the underside of the mainboard, and the booster itself. Also worth trying it with the original CPU installed to see if that works at 8Mhz.

Go over your install with reference to this: http://www.exxosforum.co.uk/atari/last/V1STE/index.htm to make sure everything is correct.

To force 8Mhz you'll need to connect the SW wire from the booster to GND, for that just use the GND ring that runs around the edge of the mainboard.

If you've connected the wire from the booster to the TOS switcher, you may well want to remove that until 8Mhz operation is verified.

You may also want to check this from the above linked page: "It has come to my attention ( here ) that some STE's may have a 74S257chip for U405. This chip does not output correct TTL voltages to drive the booster. As such the machine will likely be unstable or not boot. This IC should be replaced with a 74F257 IC. "

[exxos]

I would solder the SW pad to 0V somewhere to force 8MHz mode and see if that works first of all. You can leave CE disconnected for that test.

[Shugs81]

Nards... I have the 74s257 chip... I was determined to check that beforehand cause I thought at the time I would have it cause its just my luck... But obviously I forgot... I'll report back once I get the new chip.. Meh...

[exxos]

Nards... I have the 74s257 chip... I was determined to check that beforehand cause I thought at the time I would have it cause its just my luck... But obviously I forgot... I'll report back once I get the new chip.. Meh...

If your not working at 8MHz then the chip isn't relevant at this point.. you can rule it out just by leaving off the 32MHz wire to the booster and connect SW to GND to enable 8MHz...

Mostly issues are bad soldering jobs I have seen on the boosters, or damage to the motherboard when removing the socket.. You will have to check every CPU pin to some other ICs like the ROM sockets, you can check most of the address and databus that way so it would be a start.