Search found 31 matches

by dpalmeira
Wed Aug 10, 2022 9:47 am
Forum: Help!
Topic: c64 - ASSY 250425 Black Screen
Replies: 86
Views: 12246

Re: c64 - ASSY 250425 Black Screen

Hi banman, these docs are really helpful. I'll review these signals and compare with my working machine.

Repair and soldering video also is awesome! Great explanation, thank you so much.
by dpalmeira
Wed Jul 27, 2022 3:42 pm
Forum: Help!
Topic: c64 - ASSY 250425 Black Screen
Replies: 86
Views: 12246

Re: c64 - ASSY 250425 Black Screen

Hi, it was the MPU pin 16
by dpalmeira
Mon Jul 25, 2022 8:14 pm
Forum: Help!
Topic: c64 - ASSY 250425 Black Screen
Replies: 86
Views: 12246

Re: c64 - ASSY 250425 Black Screen

Hello, Here some facts so far: 1) I've tested the voltages in the board and they are OK. 2) During the ICs pull of process always the pin 15 (S/LUM) of VIC II chip remains LOW (no signal) 3) MPU, SID, CIA1, CIA2, PLA, VIC II, RAM Memories (x8), 74LS257 (U13 and U25), 3 ROMS (Kernal, Basic, Chars), U...
by dpalmeira
Tue Jul 19, 2022 7:18 pm
Forum: Help!
Topic: c64 - ASSY 250425 Black Screen
Replies: 86
Views: 12246

Re: c64 - ASSY 250425 Black Screen

I forgot to mention that the Dead Test don't flashes as usual, in all the process of removing or putting chips :(
by dpalmeira
Tue Jul 19, 2022 6:45 pm
Forum: Help!
Topic: c64 - ASSY 250425 Black Screen
Replies: 86
Views: 12246

Re: c64 - ASSY 250425 Black Screen

Hi, Just to tell you that if I remove all chips as you mentioned only with MPU/VIC/PLA + clock 8701 + 556 (for ready signal) and with the Dead Test Cartridge, a periodically signal appears on pin 38. Even putting all chips this signal remains while Dead Test Cart. is connected. MPU pin 15 in YELLOW ...
by dpalmeira
Tue Jul 19, 2022 11:20 am
Forum: Help!
Topic: c64 - ASSY 250425 Black Screen
Replies: 86
Views: 12246

Re: c64 - ASSY 250425 Black Screen

Ok, I will try this approach this afternoon. The good thing is that I have all IC socketed at this point. I really need to fix it, I'm learning and trying it for more than 1 year so far :S , and I'm getting almost crazy! - "Have you been testing the pins on the VIC II chip as you run your obser...
by dpalmeira
Mon Jul 18, 2022 8:57 pm
Forum: Help!
Topic: c64 - ASSY 250425 Black Screen
Replies: 86
Views: 12246

Re: c64 - ASSY 250425 Black Screen

Hello, many thank you for your effort and help, I really appreciate it. Well, I spent time trying to identify if something change checking MPU pins removing one by one the chips as you suggested, but nothing has changed, so I decided to continue removing more and more, and at the end with only MPU, ...
by dpalmeira
Sun Jul 17, 2022 11:12 am
Forum: Help!
Topic: c64 - ASSY 250425 Black Screen
Replies: 86
Views: 12246

Re: c64 - ASSY 250425 Black Screen

Pin 29 nothing special pin29.png Pin 38 , interesting thing: 1) A similar pulse of yours appears on startup, but after a second no more pulses comes: pin38.png In 2us here is the pic on start up also... pin38 2us.png 2) Finally, if I put my Dead Test cartridge, then pin 38 have this pulse periodica...
by dpalmeira
Sun Jul 17, 2022 11:04 am
Forum: Help!
Topic: c64 - ASSY 250425 Black Screen
Replies: 86
Views: 12246

Re: c64 - ASSY 250425 Black Screen

Hello! I removed the SID and take some measures as you suggested. Here are the results: Pin 15 It seems to have some quick activity on start up, and after a second go high as usual. Here is the pic during this period, some time is a almost 4v square signal, sometimes it looks like different. pin15.p...
by dpalmeira
Tue Jul 12, 2022 4:58 pm
Forum: Help!
Topic: c64 - ASSY 250425 Black Screen
Replies: 86
Views: 12246

Re: c64 - ASSY 250425 Black Screen

Hi, I share here two more videos: 1) Test MPU pins using the 6510 chip from the good board (c64-2) in my bad board c64-1 https://www.youtube.com/watch?v=DVDgqSwKKwc I think I got similar results... 2) Second video just pins 9,10,11 and 12, removing the logic chips. https://www.youtube.com/watch?v=aj...