[N8VEM: 18932] Zea SBC V 1.0

Discussion:

[N8VEM: 18932] Zea SBC V 1.0 - No joy

Don Caprio

2014-11-08 01:28:48 UTC

Hey folks,

My Zeta SBC is not working.

What I've done:

1) Reburned the EPROM (SST 39SF040) Feb28_2009_tools_Zeta.bin
2) Replaced C25-28 caps with 0.1uf tantalum, orienting polarity as in
photo on Wiki
3) Replaced TRS202ECN (TI version) with an original Maxim MAX232CPE
4) Tested all 74 series IC's on my EPROM burner.
5) Replaced Z-80 with working one. Tried original in another SBC and it
worked
6) Tested PC term and cable (Works with other SBC)
7) Set baud rate to 38400, N81
8) Using a null modem cable from Zeta to PC
9) Using 5VDC 2A power on P6
1) Green power LED is on

I've done the UART loopback test, removed the UART, shorted pins 10 &
11 (SIN & SOUT)
No characters are echo'd on the terminal.

Any ideas? Your suggestions/comments/feedback appreciated.

Thanks.
--
Don Caprio
***@gmail.com

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John Coffman

2014-11-08 01:43:04 UTC

Permalink

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The Zeta, along with the N8, will not run if the DS1210 is not in
place and properly powered with backup power. 
 
Alternately, remove the DS1210 and short 1-8, 5-6. 
 
--John 
 
 
 
On 11/07/2014 05:28 PM, Don Caprio wrote:
<blockquote cite="mid:***@gmail.com" type="cite">Hey
folks,
 
 
My Zeta SBC is not working.
 
 
What I've done:
 
 
1) Reburned the EPROM (SST 39SF040) Feb28_2009_tools_Zeta.bin
 
2) Replaced C25-28 caps with 0.1uf tantalum, orienting polarity as
in photo on Wiki
 
3) Replaced TRS202ECN (TI version) with an original Maxim
MAX232CPE
 
4) Tested all 74 series IC's on my EPROM burner.
 
5) Replaced Z-80 with working one. Tried original in another SBC
and it worked
 
6) Tested PC term and cable (Works with other SBC)
 
7) Set baud rate to 38400, N81
 
8) Using a null modem cable from Zeta to PC
 
9) Using 5VDC 2A power on P6
 
1) Green power LED is on
 
 
I've done the UART loopback test,  removed the UART, shorted pins
10 & 11 (SIN & SOUT)
 
No characters are echo'd on the terminal.
 
 
Any ideas? Your suggestions/comments/feedback appreciated.
 
 
Thanks.
 
 
</blockquote>
</body>
</html>



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Sergey

2014-11-15 19:28:25 UTC

Permalink

Regarding "no echo when connecting SIN and SOUT" - it means something is wrong with your RS232 setup. Might be terminal setup (no flow control, right?), or cable (make sure it is a null modem cable with Rx and Tx crossed), or MAX232 (check capacitor polarity - capacitor orientation on PCB had changed in newer PCB revisions... Even better use MAX232A or compatible IC that can work with 0.1uF capacitors, and ceramic capacitors)...