Freeze after warmup

[Mike]

That solder blob between the 7406 and C18 on the IRQ line definitely needs to be tidied up!

It's just a fraction of a millimetre away from the NMI line that comes from VIA #1 Pin 21. Either the blob makes direct contact between both lines or it could make a capacitive coupling at least.

You really should remove that 7406 (once again), clear up all traces in its vicinity, put in a socket instead first, re-check all traces, and then put in a new 7406.

[Linzino]

Hi!

The "solder blob" is a real mess I did
It is just partially scratched traces that may look like a solder blob.
I should have been more careful with the screwdriver... and use some plastic tool instead.
This also caused one broken trace above, which I repaired with a bridge and the
that is the reason why I could not insert a socket.

I have some questions

(1) How do I clear up the partially scratched traces? Would gently scratching the space between the traces suffice?
I can re-check the continuity and if the traces below UB4 make direct contact.
I remember checking all those traces below UB4. All seemed OK.

(2) Any advice on how to insert a socket and the bridge?
I fear I won't be able to install a socket because its legs may not be long enough to accommodate a bridge solder.

(3) Should I suspect any other chips? Color RAM? RAM? Any TTL?

[mrr19121970]

The soldering generally looks dodgy. Is PIN8 even making contact? It looks like this is not even soldered.

Sadly the boards are very fragile, and ripping an eyelet or trace can happen (I did it myself desoldering the 4066 here. It can be repaired, but is fiddly and annoying. The GND eyelet and 1mm trace managed to come off with the 4066. A small scratch & tin and a resistor leg has repaired this. Another eyelet was also slightly damaged, but the continuity meter proved there was a good contact with the trace and socket.