Pokemon,
After I looked over a cover of the ZXmore V2: notes for the construction kit, I decided to put a capacitor (471) in the C4's area and soldered it down. Still no change on the screen.
I found a wire with a single female header connector at one end and a single male header connector at another end. I put a female end on one of the 5 male headers on a J12's ground area. I put the male end of the wire on the ROM's A16, which is a pin number 2. The LED lit up blue. But, no change came from the screen, only white screen.
I have a multimeter.
I checked the ZXmore board's ROM and RAM for their voltage readings.
Pin number 32 = 4.99 vdc
Pin number 16 = same as above but 2 probes were reversed.
Then I removed the ROM, the RAM and the Z80 from the board. The screen was black because I took the Z80 off the board. I, then, put the Z80 back on the board and the screen is now white. The LED lit up blue also with the A16 grounding test. I kept the ROM and the RAM off the board for the time being.
I took out an EPM3064(IC26) off the board. The screen was black also. I tested the A16 grounding test, the LED lit blue. I, then, returned the EPM3064 to its proper socket. The screen remained white.
I took a chip off the board, one chip at one time, Result;
IC5 = No effect on the screen = white screen
IC7 = "many horizontal bars"
IC15 = Black screen
IC21 = Black screen
IC10 = White screen
IC6 = White screen
IC19 = Black screen
IC9 = White screen
IC23 = White screen
IC8 = Black screen
IC17 = White screen
Thank you very much for your comment on my videos of my board, Karl.
Yes, I can check/reprogram the flash ROM (SST39SF040)!
I am using a second socket for a height additional purpose for a ZIF socket. I really also want to use a 2764/27C64/2864 and a 64K SRAM, as a top priority, temporarily for a testing purpose since I also noticed that the board has its 2 different drawing line sizes of the IC3 and IC4. Can we do this one with these smaller ICs on the board?
What about a J8?
Do we have any way to test these resistor arrays? Maybe, 180 turn round, cracked open, or short? Measured wrong?
Will the whole original ZX80 case fit the ZXmore board?
I have a logic probe, too.
Thank you very much in advance.
Sincerely yours,
Dessony (Wm)