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Re: V2.6 under design.

Posted: Wed Dec 27, 2017 9:53 pm
by exxos
Only just got home again, but had the idea to try my plug-in prototype STE booster into this problematic board..

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IMG_2140.JPG (119.32 KiB) Viewed 2207 times

Lo and behold...

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IMG_2141.JPG (71.96 KiB) Viewed 2207 times

It is still running down and just passed 31 ram test cycles..

So I think this is still the socket problems :roll:

It is difficult to test the connection in between CPU and the socket itself. I did try testing the power rails as there is more than one connection on the CPU, and this seemed fine. So would assume all the pins would be fine as well, but it seems not :roll: all the sockets I use previously all seem to be basically fine, so I doubt this would affect any kits currently on sale in my store such as the STE booster.. Problem with sockets only seems to be more recently when I ran out of sockets during the last batch of STE boosters.

I emailed the company who claims to have invented the PLCC socket in 1965 or something.. And ask them about this issue.. So far no reply.. But then again it could be due to the holiday break..

But I think it really does not matter, I think the conclusion is that much just forget totally using PLCC sockets for the processor at least. For older chips like the blitter etc, there is unlikely to be issues with those. I never really had problems with older chips and sockets of any kind as previously mentioned in my socket thread. But I think the time is here to totally avoid using them in any new booster builds..

... And this means yet again, I have to design yet another booster PCB before I can continue with this work any more :roll:

Re: V2.6 under design.

Posted: Thu Dec 28, 2017 8:44 am
by Maeke
This also means you'll have to use smt cpu, and thus probably sell the boosters with cpu presoldered as not everyone is skillfull enough to do it or have appropriate tools.

Re: V2.6 under design.

Posted: Thu Dec 28, 2017 1:40 pm
by exxos
Maeke wrote:
Thu Dec 28, 2017 8:44 am
This also means you'll have to use smt cpu, and thus probably sell the boosters with cpu presoldered as not everyone is skillfull enough to do it or have appropriate tools.
The PLCC CPU can be solder direct to the board, but like you say, a lot of people wouldn't be able to solder this.. The problem is also, I do not have time to solder kits together either :roll:

Re: V2.6 under design.

Posted: Thu Dec 28, 2017 1:47 pm
by exxos
I managed to get the GAL into the circuit today. But I am having problems getting it running at 16Mhz. Everything looks fine signal wise, so I'm not sure what is going on here. It is all stable at 8 MHz. I think it may be an issue to do with /DTACK arriving fractionally too early again :roll:

I think on the original the 2.2 design the signals are cleaned up and actually slightly harder to drive than this new circuit which is actually altering the timings just enough for it not to function. On my the 2.5 design, I had to re-sync /DTACK by the PLD in order for it to work at all. I cannot do this with the current GALs or design :( so I think I'm just going to abandon this series totally now.

Originally I thought it will be relatively straightforward and simple to create a lower cost V2.2 booster design where I could produce it in lower quantities. Considering this is turned into a total nightmare, I think it is just better to abandon this design totally and move on with the v2.5 design is listed here.

viewtopic.php?f=7&t=45

With that design I use a larger PLD, where I rooted a lot of signals via the PLD so I have better control of timings and can fix potential errors. There is honestly no use in trying to fix this current design, when the fixes basically to use larger PLD, which I've already started in another V2 variation.

Re: V2.6 under design.

Posted: Thu Dec 28, 2017 5:43 pm
by IngoQ
exxos wrote:
Thu Dec 28, 2017 1:40 pm
The problem is also, I do not have time to solder kids together either :roll:
New hobby of yours? :mrgreen:

Sorry, couldn't resist ;)

Re: V2.6 under design.

Posted: Thu Dec 28, 2017 5:52 pm
by exxos
IngoQ wrote:
Thu Dec 28, 2017 5:43 pm
New hobby of yours? :mrgreen:

Sorry, couldn't resist ;)
ahh, voice recognition doesn't always get it right, and I don't always notice :lol:

Re: V2.6 under design.

Posted: Thu Dec 28, 2017 6:56 pm
by exxos
Project abandoned.

As mentioned previously, I am abandoning the 2.6 design altogether and concentrating on the 2.5 design is stated in the thread below.

I am also officially discontinuing the 2.2 design also.

viewtopic.php?f=7&t=45

This topic is now locked as there will be no more posts relating to this design.