Brett's STE - Repair thread

[rubber_jonnie]

Just a thought.. When you say your limiting the amps, do you mean you have the psu set to limit at say 2.5amps, or have you limited the amps the STE is trying to pull ?

It is dependent on voltage and other things, but a machine doesn't always pull the same amount as another. So if the machine is trying to pull 2 Amps, and your limiting to 1.8amps, then it will add to your troubles.

My spare SR98 is rated for 3A at 5v, so I did try it with 3A on the bench PSU, but never saw much over 1.5A, so I set it to that initially, but it was hitting the limit with Brett's machine, so I upped it slightly.

I currently (!!) have current limiting on the bench PSU set to 1.6A @ 5v. It does work for my own STE, which peaks at about 1.3A and Brett's is 1.5A

Testing his CPU in my STE, you could see it pulling more, so the extra is definitely his CPU compared to mine.

Bottom line is I changed this pretty early on to take account of the bench PSU hitting my limit and potentially causing problem with Brett's machine. It's no longer hitting the limit any more.

I don't want to work on a machine directly connected to the mains, with mains voltage on the heatsinks, plus I wanted to limit the max current in case of a short, Hence the bench PSU.

[Badwolf]

I can see the headline: "Squid like creature attacks Atari STE"

That's not a knife...

IMG_5078.jpeg

:lol:

BW

[rubber_jonnie]

I can see the headline: "Squid like creature attacks Atari STE"

That's not a knife...



IMG_5078.jpeg


:lol:

BW

Lol, that all seems a bit familiar!! Even to the extent of the LA being upside down :)

[olivier.jan]

I did try both diag carts, but still nothing. I need to hook up my 2nd bench PSU before I try the serial port though as I think the serial ICs need 12v. I'll see if I can at least do that. I had done it initially but got nothing.

If you’ve got a usb to serial adapter you can also grab RX and TX from pins 8 and 9 of MFP at 5V and avoid adding a second bench PSU.

[rubber_jonnie]

I did try both diag carts, but still nothing. I need to hook up my 2nd bench PSU before I try the serial port though as I think the serial ICs need 12v. I'll see if I can at least do that. I had done it initially but got nothing.

If you’ve got a usb to serial adapter you can also grab RX and TX from pins 8 and 9 of MFP at 5V and avoid adding a second bench PSU.

Annoyingly I don't have a USB to serial adapter!! I did have but now can't find it :(

As for bench PSUs I do have two, precisely for this sort of thing, so it's not too much of a problem.

[rubber_jonnie]

@BrettRogersUK I think you're going to like this post.

This was my workbench earlier after going through all of the connections on the ROM sockets:

IMG_20220130_185856.jpg

So why not woking still I was wondering, I have traced all of the lines top and bottom and they ALL go to where they should.

Then I was probing the lower data strobe at the CPU and this happened when I hit reset:

IMG_20220130_190953.jpg

Ok, so the diag cart works, lets see if we can get to the desktop, so pulled the diag cart and this:

IMG_20220130_191030.jpg

So it seems there is a second problem with the CPU socket not making good contact with the CPU. Unfortunately I can't get it to boot and be stable right now, so I need to do some work on the socket, possibly even replace it, though I will try to fix it first.

Feel free to have a bit of a celebration, because we now now that the ROM socket and trace repairs are probably good and we just need to deal with the CPU socket now.

Pheeew! That was a lot of buzzing out this afternoon just to prove my work!!

[exxos]

:bravo: :goodpost:

[stephen_usher]

:dualthumbup: :yay2: :yay: :girldance: :bravo:

[DoG]

:thumbup:

[JezC]

@rubber_jonnie Excellent progress!

Well done that man! :2k2: