| |
Hi,
I've a dead board here and don't know what to do anymore...
The following is happening:
I can download the pcode to the board, but when I then try to reset the
board, the IC message won't show up on the display, there won't be any beep,
and IC reports that I can't establish connection with the board. The LCD
looks like there is now pcode loaded.
I've tried the following things:
- removed all ICs and followed the test instructions in the assembly manual.
The first test failed was "Running the 6811 Software"
- replaced the 6811, the RAM chip, the 74HC132, the LCD with parts from a
perferctly working handy board. I also tried all of our parts in this
working handy board and they worked perfectly
- the E-clock signal looks kind of wierd after I removed all ICs. It was a
perfect square wave with 2 MHz and 5 V with the ICs still on it, but now it
is still a square wave but it shows a peak of 6.6V at the beginning of each
part of the square wave.
- I checked a lot of connections for continuity
- all soldering still looks OK
What had happened? I have no idea. I didn't use the board for about two
weeks and now I suddendly is dead.
Can anybody help me please?
Thanks.
Patrick Schmid
|
|
Message has 1 Reply:
 | | Re: HELP!! Dead board
|
| You shouldn't be seeing voltages over 5v anywhere in the logic circuits. Test if the 7805 is producing more than 5v, or if the RAM circuit (which is on a separate regulator) has more than 5v. In practice I'd rarely see more than a 0.2v error from (...) (24 years ago, 30-Nov-00, to lugnet.robotics.handyboard)
|
2 Messages in This Thread:
 
- Entire Thread on One Page:
- Nested:
All | Brief | Compact | Dots
Linear:
All | Brief | Compact
|
|
|
|
