Board Status
2016-09-30:
Switching out the bus driver from a TI- to an NPX-model unfortunately did not solve the problems. This presents a true challenge for Medusa, since some of the behaviours of the board still are a mystery. You can probably imagine the enormous pressure this puts mostly on Fredi Aschwanden, in order to finally begin delivery of the computers. Nevertheless, we will only start with that as soon as all problems are actually solved. We want the computers to work a 100%, just like the first series. For this reason, we would like to thank all of you end-users for your infinite patience. Especially those, who have made a down payment a long time ago already.
As next steps, we will try to tackle the issue with two measures. On the one hand, the thermal pad of the bus driver will be removed from one of the boards. The "thermal pad" is a metal surface on the lower side of the chips which is connected with 3V3. It serves to dissipate the heat over the layer surface, in this case 3V3. This "pad" should not have contact to any other connector of the chip, according to the specification. But apparently there is contact as soon as the chip is powered on; contact which heates the chip, and leads to an increase in power consumption so strong that the power supply collapses. On the other hand, we will have one of the boards fitted with an identical bus driver instead of the current one, but one which contains internal pullups, preventing the inputs from falling into undefined states. The reason is that there is a suspicion that these inputs start to oscillate or assume irregular states during power-up, and by doing so, destroy the chip.
We hope that one of these two measures will lead to a solution for the problem, but at this point, we cannot make any promises. Additionally, Wolfgang Förster has just recently offered his help, being one of the few with deep hardware knowledge.
Since there was a question in a forum about the technical realisation of such a "component exchange", we want to assure you that this is carried out absolutely professionally by the assembly company. It would be wrong to think of this as some manual tinkering and soldering. There are several highly complex automatic machines for such tasks used by the assembly company. As a result, a user will not even notice if any component of the board had been replaced. This wouldn't even be possible to do in any different way, with close to 1000 SMD parts on an 8-layer curcuit board. Here is an infomercial of such a machine: https://www.youtube.com/watch?v=UY2MFbk-bN0, in this case a Zevac Onyx. As was always the case, the boards will be delivered by Medusa with a 2-year warranty!
 2 Comments
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 | JoeIron :: 2016-10-04 07:27:40
Thanks for the update and the dedicated work of the whole team!
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| Vido :: 2016-10-04 08:39:15
Thanks JoeIron! I believe you can expect soon more encouraging (good) news ;)
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