Before we get lost in this, I just wanted to say...We have an exciting new feature for our Q68s. One that gives the Q68 access to floppies, microdrives and other QL expansions! Martyn Hill has adapted and written an amazing driver, and we should be focusing on the positives of that, rather than tearing down any accompanying hardware that doesn't fit our preconceived notions. I was so happy when Martyn announced his driver, because it opens up a realm of possibilities for the Q68 we didn't have before. I only designed the PCB, as open hardware that is freely available to the whole community to use or alter in any way they wish - including you, Derek - because I recently complained that it was a shame hardware developers were a bit stuck because software developers were not supporting our hardware creations with drivers. Much hardware does not exist just because of the prospect of absense of drivers. Why even develop the hardware if it will never work, because the community is too small to develop for and support it? When Martyn released this amazing new driver, I realised the opposite problem was also true, and that hardware should be quickly available.
Nobody is making anyone use the PCB, or stopping them from modifying it to their own design.
Derek_Stewart wrote:It is pity you never listed proposals before performing all the work on the PCB design.
It was based on previous work. It was already done. I didn't realise I needed to get or seek approval for my designs from anyone.
Can you please refer me to any documentation that describes the intended expansion connectors and board outlines for Q68 expansions? I have not seen any. The case was not designed to accommodate any kind of expansion, as none were anticipated.
Derek_Stewart wrote:It looks to me after an examination of the Q68 PCB, the logical way would be to orientate the expansion board perpendicular to the front panel or in line witht he expansion connector, only 2 holes would be required in the side of the case wall. The Network Sockets could be connected to the Expansion PCB by a wire link to the PCB. This would allow assembly of the Q68 to remain the same. But I am sure you will come up with all sorts of reasons why this should be done but I am reluctant to have the power switch at the side or an inline power switch on the power cable.
This is introducing non standard approach to the Q68 design.
You said, paraphrased, you do not like the power switch on the left side, because you have to "drill through the PCB guide rails and the drill bit might jam" and then said, "we should put the sockets on the left side," as if they are somehow immune to the drill bit problem.
I examined the case and PCB and made the following conclusions: I agree that putting any interface in the left side of the case is a nonsense, because it is not possible to assemble. The jacks do not have clearance to allow the Q68 PCB to slide into the case. The switch does, but only just. However, the switch is also on wires so has flexibility of motion relative to the PCB. I searched and did not find any panel mount 3.5mm sockets that also contained a switch. This is because the design of the 3.5mm jack requires a relatively short ground pin on the shaft. Even if I could, they couldn't clear the depth of the PCB guide rails combined with the enforced relationship with the power socket height. So the sockets available simply won't mount securely on the side and still allow assembly of the case.
How do you mount the sockets in the side holes then insert the PCB? You have to part-insert the PCB into the case so the power connector passes the mounting holes, then mount the two sockets, connect them to the PCB, then insert the PCB the rest of the way. They can't be soldered to the PCB or they would have a fixed relationship to the Q68 and would conflict with the case edge. If you recess them to where they would not conflict with the case when sliding the PCB in, an inserted jack would not latch and make full electrical contact.
Conclusion: side mounted anything: hard or impossible to mount, to assemble, and to obtain the parts.
I looked at the rear of the case. There is simply no clearance.
I looked at the front of the case. There is clearance along the entire top of the front of the case, except over the power socket, which lacks 2mm of clearance. I looked at placing the sockets over the SD slots, but it was problematic. I realised if the power switch were removed, and another hole drilled 10.5mm to the right, the two sockets would fit well, alongside the other thin cable that always has to be there for power and thin cable that might be there for audio. This also allowed the use of commodity parts, and the drilling of a flat, removable, replaceable plate.
The PCB does not preclude people from obtaining their own panel mount 3.5mm switched sockets and placing them anywhere they like. If they want to follow your scheme, they can. However, no such sockets are available on digikey, mouser, arrow, element14, or alibaba sites with the required 6mm threaded depth to allow securely fixing to the side wall of the case.
So, there was no need to list proposals. Once the obviously impossible options were ruled out, the only locations were "with all the other thin cables" or "in the way of the SD cards."
Take your pick
The logical answer is to add the expansion BELOW the Q68, which would give good clearance on all sides. The board I have designed will also fit below the Q68, if anyone desires to design a new case.
If you don't like my design, Derek, design a better one
. If you don't agree with my conclusions, test your own then discover why I excluded them early on.