Troubleshooting Help Needed Rev3 Board
A single board computer using an electromechanical CPU
Brought to you by:
jhallen
Menu
▾
▴
Hi everyone!
I just finished building the computer and turned it on for the first time and all LEDs in the "Write Data" turn on except 1 and 0 (other LEDs turn on correctly according to the video).
Also when I check the "FF" then <step>, all LEDs in "PC" turned on except 2 and all LEDs in "Write Data" also turned on except 0 and 1. I checked all my soldering, relays, and holding resistors and nothing seems help. When I started running the demo program, it will always stuck at the fifth step and start looping with 0090E890 at address 00.</step>
As I sucesscively pressing <step>, the pc only count up to 3 (the LED at PC2 won't turn on) and loop back to 0 1 2 3.</step>
I tried to replace the relay at PC2, AGATE1 and AGATE0 still doesn't fix the problem. All LEDs are still fully function when I applied voltage.
Thank you so much for your help.
Last edit: Vinh Pham 2019-12-31
Hi Vinh,
Try setting the clock speed low, "FREQ 2" or something. Now try to "FF" and <step>. Do you see the PC bit 2 temporarily being set? I mean do you see the LED turn on and the turn back off?</step>
If you never see the LED turn on, it's got to be some kind of wiring problem. It should be slow enough that you can trace the signal back to the peripheral driver with a meter.
If you do see the LED turn on, but it won't stay on, then either the holding resistor is not connected (unlikely), or you need to find a better relay- try swapping the PC.2 relay with others.
Joe
Thank you for replying,
The LED doesn't turn on at all. When I removed the relay from PC2, it would turn on. How do you recommend to trace the signal back to the peripheral driver?
Thank you again
Vinh,
Congratulations on building a Relay Computer.
I assume you downloaded a copy of the schematics and pcb artwork files (found in the files section on this site).
Which relay did you remove for PC2?
Using the schematic and the PCB artwork files you can determine the signal path. Do you have a DMM or a Ohm meter? You can use these to trace the signal path (power off of course). It can be a bit tedious, but
I would start at the PC2 LED, tracing back to R59 and continue tracing from there.
Did you solder-in the IC's or did you use sockets? If you used sockets make sure that none of the IC pins got bent when you inserted the IC's.
Last edit: Francis Bauer 2020-01-01
Thank you for your tips! I finally able to troubleshoot the problem with tracing.
Happy New Year!
Vinh,
Great, so you now have a running Relay Computer.
How do you like the sound? What model Relays are you using?
If you haven't already, search these discussions for info/pointers to additional Relay Computer programs. There a few that are pretty awesome. You will need to setup a simple Serial connection from your PC to your RelaySBC to make you life easier in loading and storing programs. The Serial connection also gives you a Terminal console into the RelaySBC.
To help you create your own RelaySBC programs, be sure to check out the Assembler and Simulator tools that Joe Allen created. With these tools you can develop/test new programs on your PC and then load them into the RelaySBC. This speeds up the development process by quite a bit.
Enjoy...
I love the sound! I'm using the HFD27/012-S relays for the non-matching ones to save money ($0.36/ea) and it works great. I'm still playing around with the simulator and see what it can do.