Looks like I'll be getting a Mega ST4 soon

[exxos]

Spray the socket and CPU with this

https://www.rapidonline.com/electrolube ... ml-87-0706

[rubber_jonnie]

Spray the socket and CPU with this

https://www.rapidonline.com/electrolube ... ml-87-0706

So your suggesting that the socket may have a coating from manufacture that's preventing good contact?

[exxos]

Assuming the soldering is good and you not damaged any tracks or pads, then bad contacts is next logical step. I've had troubles with solder pins and sockets. Any contacts are always questionable even more so when stuff ages.

[rubber_jonnie]

@exxos

I guess that is reasonable.

Quick q, when using the diag ROM cart in ST mode, does the serial cable need to be null modem?

[exxos]

Quick q, when using the diag ROM cart in ST mode, does the serial cable need to be null modem?

No idea sorry. Think I just got a serial cable off evilbay years ago and it worked.

[rubber_jonnie]

OK, thanks.

[exxos]

Assume they just a normal crossover serial cable. But if your CPU isn't running the diagnostic cart isn't going to help anyway.

[DoG]

If you connect computer thru computer, you will need a null modem cable. There is a few lines that crossed in the cable. Like transmit-receive, handshake and one more. But there are different kind I suppose.

[derkom]

Quick q, when using the diag ROM cart in ST mode, does the serial cable need to be null modem?

I have used the diag cartridge successfully with a null modem cable. Never tried a straight through, but I imagine it would not work.

[rubber_jonnie]

Thanks all, I did try the diag cart with a working machine, but got zilch, so I'll have to pay a visit to my big box o' cables as I think I have some null modem adapters in a bag.

If not I'll see what I can do about getting one sorted.

Typically this sort of thing usually requires null modem but it's nice to be sure.

Having had a really close look at all of the sockets, as there are quite a few socketed chips (ROMs, Shifter, DMA, Blitter, Glue & MMU), the contacts are all badly oxidised/dirty, so I think a can of contact cleaner is in my future.