The Sinclair QL Forum

Hello,

my QL crashes/freezes after some time of use.
Could this be a general heat problem?

I made a picture of the board with a disk interface attached on the left.
This heat sink of the interface becomes VERY hot after a while!
And does anybody knows, if these "modification" on the CPU are standard or anything selfmade?



I don't know what is common for such an old machine and what is a real error - as far a I remember my first QL in the 80ies also crashed from time to time due to unknown reasons...

And this "new" German QL has also problems with the point command: it generates always two pixels (same as the first 25 years ago). Is there any known solution for this bug?

I have to admit that I don't use this machine very often but I would like to maintain it and resolf the major bugs.

Thanks for any feedback!

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

Hello Tobias,
thanks for all your information and for the hint with these regulators.
I exchanged both - in the QL and on the disk controller.
System is working, so my modification didn't damage anything.
Let's see, if it will be more stable in the future.

Andi B. wrote: Let's see, if it will be more stable in the future.

Andi,

please do report back on how this works.

Cheers,
Tobias

Horace goes QL'ing

vanpeebles wrote:Horace goes QL'ing

Horace on the hot tin roof (or rather heat sink?). See he nearly burnt his feet.

Poor Horace!

I never thought this board comes with different problems. It is a little bit hassle to do every modification. Hope everything will work fine after you did this.

With regards to the modifications to the QL board. You could remove the 2 chips and replace them with 2 unmodified chips to see what effect it has, without some research, not sure of the purpose. I will get back after looking at my QL Service manual.

The heat sink looks too small on the disk interface, but the designers must of calculated the minimum size for the interface to operate efficiently.

Derek