[N8VEM: 18408] Mark IV Troubleshooting

Discussion:

Anthony DeStefano

2014-07-10 01:18:15 UTC

I've been banging my head for about 3 days now trying to get a Mark IV
to run the TEST1B.BIN successfully. So far I can verify the following:

1. I'm using a Z8S18033 with a 18.432 oscillator and have a good clock
on pin 3 and 1/2 on PHI pin 68.
2. The power LED goes green and stays green.
3. I checked all sockets for voltage and ground and all are okay.
Nothing it getting hot to indicate a true short
4. Reset seems to be working correctly. At least I see it drop on pin 1
of U31.
5. ROM is a SST39SF040 flash programmed with the minipro programmer. P11
and P12 are in the 2-3 position for flash.
6. I'm using SN74LS for all the logic chips.

Like many on the list this is my first major digital electronics
project. I do have access to a scope and a Salaea 16 port logic probe.
Poking around I see various things twiddle, but I'm not sure where to
look for the fault. I've thought about trying a slower oscillator, but
would need to order one.

Any help would be appreciated.

--
Anthony DeStefano
adx-97jfqw80gc6171pxa8y+***@public.gmane.org

John Coffman

2014-07-10 08:58:15 UTC

Permalink

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Anthony, 
 
I would assume that TEST1B came from the updated zip file. 
 
LED should be green during RESET.  Good. 
 
Do you have experience wiring RS-232 communications cables?  The
output from the Mark IV board, like the SBC v1/v2, looks like a
terminal.  Hence, to connect to a terminal you must cross lines
through a null modem. 
 
Check the Serial Interface tutorial; it applies to all boards: 
<a
href="http://n8vem-sbc.pbworks.com/w/page/44302435/Serial%20Interface%20tutorial">http://n8vem-sbc.pbworks.com/w/page/44302435/Serial%20Interface%20tutorial</a> 
 
Make sure the TXD from the Mark IV is connected to the RXD of your
PC or Terminal.  Electrically, see if the output is toggling as
characters are transmitted.  Trace back through the MAX233 to be
sure the TTL level output from the Z180 is transmitting, too. 
 
Q:  Are you running the board standalone, or plugged into a
backplane?  You said you had checked the Vcc voltages across the
board. 
 
--John 
 
 
 
On 07/09/2014 06:18 PM, Anthony DeStefano wrote:
<blockquote
cite="mid:1404955095.20981.139973353.00FC1067-***@public.gmane.org"
type="cite">
<pre wrap="">I've been banging my head for about 3 days now trying to get a Mark IV
to run the TEST1B.BIN successfully. So far I can verify the following:

1. I'm using a Z8S18033 with a 18.432 oscillator and have a good clock
on pin 3 and 1/2 on PHI pin 68.
2. The power LED goes green and stays green.
3. I checked all sockets for voltage and ground and all are okay.
Nothing it getting hot to indicate a true short
4. Reset seems to be working correctly. At least I see it drop on pin 1
of U31.
5. ROM is a SST39SF040 flash programmed with the minipro programmer. P11
and P12 are in the 2-3 position for flash.
6. I'm using SN74LS for all the logic chips.

Like many on the list this is my first major digital electronics
project. I do have access to a scope and a Salaea 16 port logic probe.
Poking around I see various things twiddle, but I'm not sure where to
look for the fault. I've thought about trying a slower oscillator, but
would need to order one.

Any help would be appreciated.

</pre>
</blockquote>
</body>
</html>



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Anthony DeStefano

2014-07-12 00:13:06 UTC

Permalink

I have semi-success with TEST1B.BIN! I get the serial output,
but the SD LED doesn't turn on.

I found two problems. The first was that half of my U3 was
dead. The three inverters between pins 8-12 were all dead. I
put in a new chip tonight and it still wasn't working. Banged
my head against the wall some more, did some more logic
probing, and then finally came to the conclusion it had to be
something within the ROM access logic. So I started tracing out
all the A and D lines to the flash chip. They all looked good.
Next step was to start tracing back the CE logic. I started
getting towards the end of the chain and then I don't have
continuity between U31.1 and U29.11. Here I forgot to solder
U31.1!

All of this over a missing solder joint! However, I did learn a
lot about what the Z180 does while it has nothing else to do
and learned a lot about how to interpret the data coming out of
a logic analyzer so not all was lost. However, looking back
over things and trying it while it's working I should have
noticed that CE wasn't wiggling on U32.22 and instead was just
staying high. However, now I know for next time.

Off to try some other ROM images!

And now that I have one under my belt, maybe I should get a
6x0x board, too.

--
Anthony DeStefano
adx-97jfqw80gc6171pxa8y+***@public.gmane.org

On Thu, Jul 10, 2014, at 04:58 AM, John Coffman wrote:

Anthony,

I would assume that TEST1B came from the updated zip file.

LED should be green during RESET. Good.

Do you have experience wiring RS-232 communications cables?
The output from the Mark IV board, like the SBC v1/v2, looks
like a terminal. Hence, to connect to a terminal you must
cross lines through a null modem.

Check the Serial Interface tutorial; it applies to all boards:

[1]http://n8vem-sbc.pbworks.com/w/page/44302435/Serial%20Interf
ace%20tutorial

Make sure the TXD from the Mark IV is connected to the RXD of
your PC or Terminal. Electrically, see if the output is
toggling as characters are transmitted. Trace back through the
MAX233 to be sure the TTL level output from the Z180 is
transmitting, too.

Q: Are you running the board standalone, or plugged into a
backplane? You said you had checked the Vcc voltages across
the board.

--John

On 07/09/2014 06:18 PM, Anthony DeStefano wrote:

I've been banging my head for about 3 days now trying to get a Mark IV
to run the TEST1B.BIN successfully. So far I can verify the following:

1. I'm using a Z8S18033 with a 18.432 oscillator and have a good clock
on pin 3 and 1/2 on PHI pin 68.
2. The power LED goes green and stays green.
3. I checked all sockets for voltage and ground and all are okay.
Nothing it getting hot to indicate a true short
4. Reset seems to be working correctly. At least I see it drop on pin 1
of U31.
5. ROM is a SST39SF040 flash programmed with the minipro programmer. P11
and P12 are in the 2-3 position for flash.
6. I'm using SN74LS for all the logic chips.

Like many on the list this is my first major digital electronics
project. I do have access to a scope and a Salaea 16 port logic probe.
Poking around I see various things twiddle, but I'm not sure where to
look for the fault. I've thought about trying a slower oscillator, but
would need to order one.

Any help would be appreciated.

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References

1. http://n8vem-sbc.pbworks.com/w/page/44302435/Serial%20Interface%20tutorial
2. mailto:n8vem+unsubscribe-/***@public.gmane.org
3. mailto:n8vem-/***@public.gmane.org
4. http://groups.google.com/group/n8vem
5. https://groups.google.com/d/optout

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Anthony DeStefano

2014-07-12 00:31:22 UTC

Permalink

Quick follow-up. The SD LED is working fine. The problem is my
yellow LEDs are very dim and I didn't notice the quick blink
with my lamp shining down on the board.

--
Anthony DeStefano
adx-97jfqw80gc6171pxa8y+***@public.gmane.org

On Fri, Jul 11, 2014, at 08:13 PM, Anthony DeStefano wrote:

I have semi-success with TEST1B.BIN! I get the serial output,
but the SD LED doesn't turn on.

I found two problems. The first was that half of my U3 was
dead. The three inverters between pins 8-12 were all dead. I
put in a new chip tonight and it still wasn't working. Banged
my head against the wall some more, did some more logic
probing, and then finally came to the conclusion it had to be
something within the ROM access logic. So I started tracing out
all the A and D lines to the flash chip. They all looked good.
Next step was to start tracing back the CE logic. I started
getting towards the end of the chain and then I don't have
continuity between U31.1 and U29.11. Here I forgot to solder
U31.1!

All of this over a missing solder joint! However, I did learn a
lot about what the Z180 does while it has nothing else to do
and learned a lot about how to interpret the data coming out of
a logic analyzer so not all was lost. However, looking back
over things and trying it while it's working I should have
noticed that CE wasn't wiggling on U32.22 and instead was just
staying high. However, now I know for next time.

Off to try some other ROM images!

And now that I have one under my belt, maybe I should get a
6x0x board, too.

--
Anthony DeStefano
adx-97jfqw80gc6171pxa8y+***@public.gmane.org

On Thu, Jul 10, 2014, at 04:58 AM, John Coffman wrote:

Anthony,

I would assume that TEST1B came from the updated zip file.

LED should be green during RESET. Good.

Do you have experience wiring RS-232 communications cables?
The output from the Mark IV board, like the SBC v1/v2, looks
like a terminal. Hence, to connect to a terminal you must
cross lines through a null modem.

Check the Serial Interface tutorial; it applies to all boards:

[1]http://n8vem-sbc.pbworks.com/w/page/44302435/Serial%20Interf
ace%20tutorial

Make sure the TXD from the Mark IV is connected to the RXD of
your PC or Terminal. Electrically, see if the output is
toggling as characters are transmitted. Trace back through the
MAX233 to be sure the TTL level output from the Z180 is
transmitting, too.

Q: Are you running the board standalone, or plugged into a
backplane? You said you had checked the Vcc voltages across
the board.

--John

On 07/09/2014 06:18 PM, Anthony DeStefano wrote:

I've been banging my head for about 3 days now trying to get a Mark IV
to run the TEST1B.BIN successfully. So far I can verify the following:

1. I'm using a Z8S18033 with a 18.432 oscillator and have a good clock
on pin 3 and 1/2 on PHI pin 68.
2. The power LED goes green and stays green.
3. I checked all sockets for voltage and ground and all are okay.
Nothing it getting hot to indicate a true short
4. Reset seems to be working correctly. At least I see it drop on pin 1
of U31.
5. ROM is a SST39SF040 flash programmed with the minipro programmer. P11
and P12 are in the 2-3 position for flash.
6. I'm using SN74LS for all the logic chips.

Like many on the list this is my first major digital electronics
project. I do have access to a scope and a Salaea 16 port logic probe.
Poking around I see various things twiddle, but I'm not sure where to
look for the fault. I've thought about trying a slower oscillator, but
would need to order one.

Any help would be appreciated.

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References

1. http://n8vem-sbc.pbworks.com/w/page/44302435/Serial%20Interface%20tutorial
2. mailto:n8vem+unsubscribe-/***@public.gmane.org
3. mailto:n8vem-/***@public.gmane.org
4. http://groups.google.com/group/n8vem
5. https://groups.google.com/d/optout
6. mailto:n8vem+unsubscribe-/***@public.gmane.org
7. mailto:n8vem-/***@public.gmane.org
8. http://groups.google.com/group/n8vem
9. https://groups.google.com/d/optout

William R Sowerbutts

2014-07-10 09:35:02 UTC

Permalink

Anthony

Are the P10 jumpers (to set the I/O address for on-board devices) set
correctly?

Note that a jumper across the pins makes a logical zero bit, absence of a
jumper makes a one bit.

Will

Post by Anthony DeStefano
I've been banging my head for about 3 days now trying to get a Mark IV
1. I'm using a Z8S18033 with a 18.432 oscillator and have a good clock
on pin 3 and 1/2 on PHI pin 68.
2. The power LED goes green and stays green.
3. I checked all sockets for voltage and ground and all are okay.
Nothing it getting hot to indicate a true short
4. Reset seems to be working correctly. At least I see it drop on pin 1
of U31.
5. ROM is a SST39SF040 flash programmed with the minipro programmer. P11
and P12 are in the 2-3 position for flash.
6. I'm using SN74LS for all the logic chips.
Like many on the list this is my first major digital electronics
project. I do have access to a scope and a Salaea 16 port logic probe.
Poking around I see various things twiddle, but I'm not sure where to
look for the fault. I've thought about trying a slower oscillator, but
would need to order one.
Any help would be appreciated.
--
Anthony DeStefano
--
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_________________________________________________________________________
William R Sowerbutts will-***@public.gmane.org
"Carpe post meridiem" http://sowerbutts.com
main(){char*s=">#=0> ^#X@#@^7=",c=0,m;for(;c<15;c++)for
(m=-1;m<7;putchar(m++/6&c%3/2?10:s[c]-31&1<<m?42:32));}