I am building the Apple 1 kit and need help. Checked all soldering and power supply. Did not populate the CPU section since I cannot get past the display driver starting up. Stuck at the section where it is suppose to display the test pattern in the documentation. Never got that.
I have a scope and can look for problems if I know what I am suppose to look for. I thought that my old CCTV monitor could be the problem (works with old VCR) so I borrowed a friends Apple //c monitor. Same issue.
Mimeo board and I followed build guide. All parts from Unicorn (Apple1PartsKit ). Soldered for 40+ years, very neat job and double checked all sockets, caps, resistors. Checked all Power and everything matches.
I followed the instructions from jwbavalon
Hi eackerman, my suggestions are for the Mimeo board but should help. You may want to start a new topic and describe your setup and what you have done todate in detail.
Remove all the chips from rows A and B. Remove D2 (2513), C3 (2519) and D4a, D4b, D5a, D5b, D14a, D14b and C11b (2504).
1) Video section displays 40 x 24 fixed "█" symbols (with no 25xx parts present)
2) Video section displays 40 x 24 fixed "@" symbols (with only 2513 present)
3) Video section displays 40 x 24 flashing "@" symbols (with 2513 and 2519 present)
4) Video section displays full screen of flashing "_@" symbols (with all 25xx parts present) and can be cleared with CLR line
Once you reach step 4, use your scope to observe pins 1 and 5. They should be very similar.
Once the videop is working properly, then populate rows A abd B.
After Step 1 here is what I get on the screen. I have pulled the power a couple of time and everytime it shows the same thing. What could it be??
Could it be a bad 74166? When I pull that chip I get NO image.