The Sinclair QL Forum

NormanDunbar wrote:What I find amazing about the people on here is that even though the QL is, ahem, 35 years old nearly, we still have people coming up with great ideas on how to make it better.

Sometimes I miss being able to get my hands on the new stuff as it never seems to wotk with QPC due to an incompatible extension slot!

Cheers,
Norm.

plenty of the old black boxes coming up on Ebay at the moment

I have three dead ones in a box in my basement. A project for "some time when I have time". I think it's mostly keyboard membrane problems, but after a few years in a box, possibly the electrolytics are shot, perhaps.

Cheers,
Norm.

NormanDunbar wrote:I think it's mostly keyboard membrane problems, but after a few years in a box, possibly the electrolytics are shot, perhaps.

Normally, the electrolytic capacitors in a QL are fine. And even if some have degraded, it's not terminal.

Mark

The electrolytics in the QL power section are pretty solid. I don't think I have ever seen one fail.

That said, I would make changes. Given newer chemistries that make capacitors smaller with larger capacities, I would:

Swap C42, 47uF 10v for 200uF, and also place 22uF ceramic caps across input to ground and output to ground on the 7805. Finally, you couldn't do more for your QL than to run a thicker wire directly from the output of the 7805 to the +5v pin right in the middle of the DRAM (pin 28 of IC4 and IC13.) Finally, a 47uf 6v electrolytic across pin 13 (+) and pin 15 or 35 (-) of the CPU is a pretty cool thing to do to your system too.

Wow, we totally hijacked this thread!

Cheers Dave. When, if, I get a chance, I'll see what transpires.


Nirm.

Dave wrote: Wow, we totally hijacked this thread!

Don't worry about it, it will return to it's path as soon as i can make the sugested things, meanwhile, the lessons are very interesting............