The Sinclair QL Forum

I'm currently reverse engineering the layout of the SGC. If there isn't a published schematic I'll put mine up when it's done.

Sounds like time to hit that whole board with some contact cleaner, and to wiggle/reseat all the ICs.

Or I bought them and forgot One of those

I offered to buy them but nothing came of it. My offer stands.

Is that a smear of thermal paste on the CPU? Some thermal paste is also electrically conductive and it may be making a very slight short between pins? But also, SIP RAM is the likeliest cause as others have said.

Tetroid's already done that - just needs to pay the little extra to make it a 4-layer board. 98% of the effort is just in reproducing what he's already done. If I were going to invest that amount of effort I'd just finish Issue 8.

RC networks are fine if they're tuned to the characteristics of the circuit and the frequency of the rise time. The problem with the QL is that interfaces span enough period that the range of rise times/frequencies is quite broad, so you just have to target the center frequency. When I say, "fr...

Looks like questions were asked and eloquently answered. :D There's no need for termination on the backplane if a card occupies the last expansion slot. If a backplane were to have termination, it can become quite a complex issue. Passive termination usually involves a resistor to ground, but that r...

I use the quite nice Tetroid backplane in my set-up, especially as I am regularly adding and removing cards. I was testing a floppy interface and it failed after a few hours of use. It was the only card. The two failed 74-family logic ICs were replaced but it failed again shortly after, the same way...

What about using the AY-3-8910 or YM2149?