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Re: non-socketed CPU

Posted: Tue Oct 17, 2017 8:58 am
by IngoQ
Hiya,

Since I have the STE booster, could the same be achieved with this one, or do I really have to toss it and buy another one?

Re: non-socketed CPU

Posted: Tue Oct 17, 2017 9:00 am
by exxos
IngoQ wrote:
Tue Oct 17, 2017 8:58 am
Hiya,

Since I have the STE booster, could the same be achieved with this one, or do I really have to toss it and buy another one?
The both pretty much the same design. Just different PCB layout.

Re: non-socketed CPU

Posted: Thu Oct 19, 2017 4:18 pm
by IngoQ
exxos wrote:
Mon Oct 09, 2017 4:28 pm
Also you will need to change the resistor packs on the motherboard for 2.2K ones, as the ones on the booster board will be isolated from the CPU.
Slowly trying to understand, how this all works... until now it only was mechanics for me, basically ;)

As far as I understood, this refers to the pull-ups on adress and databus, so P101-P103 and P104-P105, am I right? These have originally (at least in the schematics) 4.7k and 10k. You change them to 2.2k, because the original ones do not raise the levels fast enough for 32MHz?

Re: non-socketed CPU

Posted: Thu Oct 19, 2017 4:28 pm
by exxos
IngoQ wrote:
Thu Oct 19, 2017 4:18 pm


Slowly trying to understand, how this all works... until now it only was mechanics for me, basically ;)

As far as I understood, this refers to the pull-ups on adress and databus, so P101-P103 and P104-P105, am I right? These have originally (at least in the schematics) 4.7k and 10k. You change them to 2.2k, because the original ones do not raise the levels fast enough for 32MHz?
The address and databus resistors which are 4.7k and 10k, I change them all for 2.2K. Without them machine is just simply unstable. Signals have to change faster at 32 MHz so it needs a lower value resistor.

Basically to save changing them on the motherboard, I just included them on the STE booster board itself. They then get linked with the ones on the motherboard, so the values of actually going to work out a little less than 2.2K.

Re: non-socketed CPU

Posted: Thu Oct 19, 2017 4:49 pm
by IngoQ
exxos wrote:
Thu Oct 19, 2017 4:28 pm
They then get linked with the ones on the motherboard, so the values of actually going to work out a little less than 2.2K.
Should I use 1.5k for P101-P103 and 1.8k for P104 and P105 then?

(Because 4.7k and 2.2k parallel is 1.5k and of course 10k and 2.2k parallel is 1.8k ...)

Re: non-socketed CPU

Posted: Thu Oct 19, 2017 4:52 pm
by exxos
IngoQ wrote:
Thu Oct 19, 2017 4:49 pm
Should I use 1.5k for P101-P103 and 1.8k for P104 and P105 then?

(Because 4.7k and 2.2k parallel is 1.5k and of course 10k and 2.2k parallel is 1.8k ...)
If you're removing the resistors, just use 2.2 K as replacements.

Re: non-socketed CPU

Posted: Tue Oct 31, 2017 12:01 pm
by IngoQ
Hmm, I guess the machine should start with only the resistors replaced and everything else stock? If so, then I might have another issue with this system...

Re: non-socketed CPU

Posted: Tue Oct 31, 2017 1:29 pm
by exxos
IngoQ wrote:
Tue Oct 31, 2017 12:01 pm
Hmm, I guess the machine should start with only the resistors replaced and everything else stock? If so, then I might have another issue with this system...
Yes, and apparently yes ;)

Re: non-socketed CPU

Posted: Tue Oct 31, 2017 2:03 pm
by IngoQ
Found it... while removing the resistor packages, I damaged two address lines :-( Repaired now, but I am certainly never going to change them back ;)

Re: non-socketed CPU

Posted: Tue Oct 31, 2017 3:38 pm
by IngoQ
exxos wrote:
Mon Aug 28, 2017 5:02 pm
Image
I'm not that cofortable with bending up CPU pins. I am afraid, they might break. In the above picture, it looks like you found another way of isolating the CPU clock... did you cut a trace somewhere? I followed the CPU clock until it disappeared under U203, but did not find any nice solder points...