exxos's Atari, Amiga & retro forum

terriblefire wrote: ↑Tue Aug 20, 2019 7:39 am I did a video way back of this job. It was a nightmare and those SOJ chips never stayed soldered down properly. :/

You're so not wrong, everything looks fine, and I've cleaned up a few spots with solder wick where it was bridging connections, but I just get a black screen with white borders on power up, or a red crashy screen if I boot with my diag cart plugged in, so next steps are to have a prod around see if there are any shorts I can't see under the chips, which I'm not looking forward to.

Whilst the chips appear to be nicely soldered down, it's difficult to tell, even with strong magnification, if any of the pins are not connected.

I kind of wish I hadn't started down this road now, but at least I can remove them and get it running back at 512MB if I can't fix it.

Can you get anything over serial from the diag-cart ?

I tried to solder one of those chips once, drove me nuts. Then I took to the heatgun, and the PCB warped, so I just vowed never to try it again

I was going to try this upgrade. Dont think I'll bother now

exxos wrote: ↑Sun Aug 25, 2019 9:57 am Can you get anything over serial from the diag-cart ?

I tried to solder one of those chips once, drove me nuts. Then I took to the heatgun, and the PCB warped, so I just vowed never to try it again

So far no heat damage, the solder is relatively low melting point, and I used kapton tape to insulate other components.

There are several problems here:

1. Although the pads are relatively large, chip alignment is quite difficult, and perhaps a jig may have helped.
2. The pins on the chips, despite looking even, didn't always solder correctly.
3. There is no way to see under the chip and check for shorts, even with a strong magnifying glass and really bright light.

On a positive note I have improved my hot air techniques and don't seem to be scorching/burning/warping anything any more!

I need to decide do I just remove and stay 512KB, which is a pain, or go for it and troubleshoot.

In terms of serial, is it a case of plugging in a laptop via serial and using telnet or similar over serial to connect whilst powering up to see messages?

PhilC wrote: ↑Sun Aug 25, 2019 10:27 am I was going to try this upgrade. Dont think I'll bother now

Yeah, it's a bit arse.

rubber_jonnie wrote: ↑Sun Aug 25, 2019 10:35 am
1. Although the pads are relatively large, chip alignment is quite difficult, and perhaps a jig may have helped.
2. The pins on the chips, despite looking even, didn't always solder correctly.
3. There is no way to see under the chip and check for shorts, even with a strong magnifying glass and really bright light.

Know those issues. Its one set of issues I had with the CPU soldered down on the later STE boosters. Only takes 1 pin... They all look soldered down, but normally 1 pin which is sat "in" the solder, but not actually soldered. Wiping all the pins with IPA before soldering does help, but can't solve bent pins, or pins which look OK, but are actually bent.. total PITA.

Because of all the socket issues, I went to just soldering the CPU on the PCB.. but that created even more issues, to the point, the evil sockets were lesser of the 2 evils Then there is all crazy "tolerances" on the GALs... argh....

rubber_jonnie wrote: ↑Sun Aug 25, 2019 10:35 am In terms of serial, is it a case of plugging in a laptop via serial and using telnet or similar over serial to connect whilst powering up to see messages?

Yep.

exxos wrote: ↑Sun Aug 25, 2019 10:42 am
In terms of serial, is it a case of plugging in a laptop via serial and using telnet or similar over serial to connect whilst powering up to see messages?

Yep.

Will give it a go, see what turns up then.

Ok, back to this and now got a serial cable hooked up, but even when I try a working machine, I'm not getting anything through.

I'm using HyperTerm (oldie but goodie) via an old Win 2000 laptop I use for FloImg, can anybody advise on default settings that I nee to use in terms of baud rate etc.

Thanks in advance

rubber_jonnie wrote: ↑Tue Nov 05, 2019 10:41 pm Ok, back to this and now got a serial cable hooked up, but even when I try a working machine, I'm not getting anything through.

I'm using HyperTerm (oldie but goodie) via an old Win 2000 laptop I use for FloImg, can anybody advise on default settings that I nee to use in terms of baud rate etc.

Thanks in advance

I think when I was doing this on the ALPHA I had 9600 Baud 8N1 with RTS and DTR off and Xon/Xoff handshake. I'm going from memory but am sure thats what they were.

EDIT: Just checked and yes works with those settings.

Icky wrote: ↑Tue Nov 05, 2019 11:04 pm
I think when I was doing this on the ALPHA I had 9600 Baud 8N1 with RTS and DTR off and Xon/Xoff handshake. I'm going from memory but am sure thats what they were.

EDIT: Just checked and yes works with those settings.

Thanks, I'll give it a go.