Hi Andi,
this looks like a late MGG (Samsung-made) QL. My (as-new, because bought as a backup machine that never came to real use) MGG model looks similar. I'm not sure if it's just the picture, but the modifications yours has don't look ex-works to me. I seem to recognize some flux residues. My QL has similar modifications, but a bit more professionally made. Keep them as they are.
The disk interface (with the toy-size heatsink) also looks very much like my old Sandy board.
And yes, they used to have heat problems. A lot. The linear current regulators 7805 in the QLs produce a lot of heat.
There are several possible approaches to that:
- Fit a larger heatsink (if space allows)
- improve ventilation (doesn't help too much). Some people started drilling orgies on their QL cases
- replace the 7805 regulator with a higher spec (2 Amps type 78S05)
- replace the 7805 with a drop-in switching regulator (like here:
http://www.dimensionengineering.com/products/de-sw050). I would consider this the best possible solution provided your expansion board leaves enough room. Once you're at it, you might also want to replace the QL's own regulator.
BTW: Those guys have a German distributor:
http://www.lipoly.de/index.php?main_pag ... 80_884_931. 12€, and it's yours
More drastic methods:
Some have modified their expansion boards to live from 5 Volts as opposed to the 9 (more like 12V) in the standard QL - You need a new power supply, however). There's also a chance to destroy your modified expansion board if plugged into an unmodified QL.
Other standard problems were corrosion in the cheap IC sockets that Sinclair used. It sometimes already helps when the ICs are removed from their sockets and thoroughly cleaned.
The well-known "POINT bug" was also a feature introduced in the MGG QLs that was never fixed by Sinclair. Toolkit II (to be had from Dylwin's site) helps here.
Hope this helps,
Tobias
