Hello Dave,
great, fix the interruption and got the blinking cursor back. I'm just surprised about the scratch because I didn't make it. maybe there was some connection at the beginning that was interrupted by the warmer circuit board.
Thanks for your help. I'm sorry that you spent a lot of...
Hi Dave,
the CS2 signal is missing. I recognize a strange scratch on the board interrupting on of the lines. Not sure if it is the CS2 signal but it looks like it. I try to repair the connection.
Harald
I have a small Hameg HM103 oscilloscope with one channel.
I can see the long pulses with short pauses on all 16 outputs and the pulses with different frequencies on the 4 inputs.
Harald
Hi Dave,
E2 and E3 are hidden under the ROMulator, I can’t reach to the pins. Got the signals at J4, pin1,2,3… with 250kHz, 125kHz…
BA9 = 500Hz, BA10=250Hz, BA11=125Hz, BA12=60Hz, BA13=30Hz, BA14=15Hz, BA15=7,5Hz
Harald
Hi Dave,
I checked the PIA keyboard connection.
all 10 connections (J5, 1-10) from the keyboard to the 74145 switch from 0V to 5V when the fitting key is pressed.
the 4 connections from 74145 to PIA are all permanently high, no response to keystrokes. Without PIA, the level on the 74145 is...
I have 1 PIA and 1 VIA as spares but I get the same result with all of them. The high level at CPU pin 4 is also without all PIAs and VIA and even without CPU. Where else can it come from? I can't see any other source on the schematic.
Harald
Hi all,
What I've noticed since is that the cassette motor runs all the time, I remember it should stop about 2 seconds after booting. maybe another clue to the error.
Harald
Hello Alan,
"Exchange the PIAs" meant I swapped the 2 PIAs and received no changes.
I think I have 2 good video rams and get this screen, still no cursor and no weird asterix sign any longer as in post #1.
Harald