Hi Mattis !
I'm afraid I do not have the required skills :-/
I have never used this kind of tools. However I recovered this recently:
http://actingmachines.com/img/photos/package/europacorp/tektronix_1240_b.jpg
But in the present state of my knowledge, I could not use it. Is it
difficult for a novice to learn how to use it?
If I could just know what is the principle of the verification system of
the PIO's channels A & B, and also what are the integrated circuits
concerned? That would be valuable information.
Dominique
On 17/10/2017 17:09, Mattis Lind wrote:
2017-10-17 13:56 GMT+02:00 Dominique Carlier via cctalk
<cctalk@classiccmp.org <mailto:cctalk@classiccmp.org>>:
Hi guys!
Nobody here has any information to help me to solve my problem?
Do you think I should talk about this breakdown on another forum?
If yes, have you an address to recommend me?
Thanks
Dominique
I don't know anything about the system you are about to repair but it
make use of a standard CPU which is kind of useful when the schematic
is missing. If I were you I would attach my trusty logic analyzer over
the CPU to try to trace what it is doing. Which ROM does it access
when it is doing the power up self test? Use a disassmbler on that
particular ROM and work out what flow the CPU takes in the ROM
contents and try to understand what causes it to take the decision
that something is broken.
Since my logic analyzer has fairly limited memory depth I would have
it to trigger on for example accessing the SIO.
/Mattis
On 15/10/2017 23:12, Dominique Carlier via cctalk wrote:
Hi everybody,
As I have no documentation / schematics I started to look for
computer schematics where it is about Z80 and “serial I/O
channel B”, I found a lot of data about this subject that I do
not know at all.
These information would allow me to better target the
breakdown, if any of you would consent to pass on some of his
knowledge.
In all documentation on Z80 based machines, I find the same
elements, similar architectures: CPU, PIO, CTC, SIO.
http://www.z80.info/gfx/nascom1main.gif
<http://www.z80.info/gfx/nascom1main.gif>
http://www.ep128.hu/Sp_Konyv/Pic/SIO_11.gif
<http://www.ep128.hu/Sp_Konyv/Pic/SIO_11.gif>
I interchanged with the IC of my other CPU board which are of
the same model.
http://www.zeltrax.com/classiccmp_forum/sio_issue_01.jpg
<http://www.zeltrax.com/classiccmp_forum/sio_issue_01.jpg>
But the error persists, so the problem is around.
I'm trying to find out why the SIO detects a problem on the
channel B. How does this detection system work? What are the
solicited ICs? Do they communicate through other ICs like
multiplexers or others?
I would also like to simulate the absence of this problem in
order to see if this allows my UTS to have a successful POC
test, to have again access to the setup page of the machine.
Is it possible to do something at the SIO pin 30 (W/RDYB) to
pretend that the B channel is OK?
http://www.sbprojects.net/projects/izabella/assets/images/sio1.jpg
<http://www.sbprojects.net/projects/izabella/assets/images/sio1.jpg>
Can we imagine that the problem would be at the level of what
checks channel B and not channel B itself?
I also read a lot of obscure thing about memory, and I still
wonder if a memory problem could also play a part in this
failure? You must understand that I continue to try to
troubleshoot this machine like the others, comparative logic
without advanced academic knowledge, a challenge every time.
It's even harder because I have trouble identifying the
components. I do not find any results concerning the 3/4 of
the ICs, as for example these:
http://www.zeltrax.com/classiccmp_forum/sio_issue_02.jpg
<http://www.zeltrax.com/classiccmp_forum/sio_issue_02.jpg>
And even for components like this, "AVX 224Z 8238"
http://www.zeltrax.com/classiccmp_forum/sio_issue_03.jpg
<http://www.zeltrax.com/classiccmp_forum/sio_issue_03.jpg>
(ceramic capacitor of 220nf 50v? not sure)
There is also the fact that the tracks are not visible on the
CPU board which I try to repair, so I try to locate myself by
comparing component location to the original CPU board, in
short a beautiful mess.
Meanwhile, I restore this beautiful Key Tronics keyboard which
was in a very sad condition. Here are some pictures of this
restoration (work in progress)
http://www.zeltrax.com/classiccmp_forum/keyboard2_01.jpg
<http://www.zeltrax.com/classiccmp_forum/keyboard2_01.jpg>
http://www.zeltrax.com/classiccmp_forum/keyboard2_02.jpg
<http://www.zeltrax.com/classiccmp_forum/keyboard2_02.jpg>
http://www.zeltrax.com/classiccmp_forum/keyboard2_03.jpg
<http://www.zeltrax.com/classiccmp_forum/keyboard2_03.jpg>
<http://www.zeltrax.com/classiccmp_forum/keyboard2_03.jpg
<http://www.zeltrax.com/classiccmp_forum/keyboard2_03.jpg>>
http://www.zeltrax.com/classiccmp_forum/keyboard2_04.jpg
<http://www.zeltrax.com/classiccmp_forum/keyboard2_04.jpg>
http://www.zeltrax.com/classiccmp_forum/keyboard2_05.jpg
<http://www.zeltrax.com/classiccmp_forum/keyboard2_05.jpg>
<http://www.zeltrax.com/classiccmp_forum/keyboard2_05.jpg
<http://www.zeltrax.com/classiccmp_forum/keyboard2_05.jpg>>
http://www.zeltrax.com/classiccmp_forum/keyboard2_06.jpg
<http://www.zeltrax.com/classiccmp_forum/keyboard2_06.jpg>
<http://www.zeltrax.com/classiccmp_forum/keyboard2_06.jpg
<http://www.zeltrax.com/classiccmp_forum/keyboard2_06.jpg>>
http://www.zeltrax.com/classiccmp_forum/keyboard2_07.jpg
<http://www.zeltrax.com/classiccmp_forum/keyboard2_07.jpg>
In any case I hold on, restarting this machine has become an
obsession, but without help I will still be on it for the next
10 years, thus HELP! ;-)
Everything would be perfectly fine if most of the time I
did not have at startup an error at line 9. of the POC test:
SERIAL I / O CHANNEL B: FAILED
