250469 half dead

I have 250469 that when i replaced a bad PLA (251715-01) was warking fine for 2-3 days until now.

When i turn it on, i get the screen full of vertical marks instead of normal boot screen. Then when i turn it off then on, i just get Blank black screen. After i wait 4-5 hours it will boot to the blue garbage screen again w/border.

With Cartridge, when cold it will boot to cartridge screen, then slowly the cartridge screen will disappear. After i turn it on/off, gives Blank Black screen.

I checked U2/U1 CIA,U4 Kernal/Basic,U6 MPU,U10/U11 RAM,U8 PLA,U3 74LS08,U7 VIC,U20 8701=ALL OK

pictures of the board..looks new.. i checked Voltages and ok

pulled both CIA's out, still blank black screen

remember it booth to that garbage screen only after its been sitting for 5-6 hours. And if i turn it off/on after that, it boots to Black Blank Screen everytime.

Blank commands do not work, disk drive will reset normal.

When put cartridge (after sitting for 5-6 hours) it will boot to cartridge startup screen(like Jupiter Lander) then the screen will slowly disappear.

i tried the 781220 dead test cartridge and its able to boot it everytime but as it cycles the screen will lose characters as changes to next cycle

see pic

ill check the U21 in a few hours

"You could try to see if replacing the 4066 on U21 makes a difference."

U21 4066 is OK

so still black blank screen...

could it be U23 74LS14? i never checked it, but i tried piggyback method, but nothing changed

after sitting all night, with Jupiter Lander Cartridge the game screen came on normal, then when i turned it off then on, also normal then on thord on/off Jupiter Lander screen started showing garbage characters everytime.

Without cartridge boot screen was black blank everytime.

Seems if its sits all day it will boot normal with cartridge but then after that it goes bad again?

yes..i tested the Kernal/basic in working board and its fine.. even with bad kernal/basic cartridge should boot everytime (Jupiter Lander)

I believe all the IC's are good on this board and ive checked,re-checked them in my working board many times

This board was warking fine after i replaced the 64 Pin PLA, then as i was ready to turn it on last time before putting case on, it went dark on me.

so you think its a IC causing this?

Only IC's i havent checked are U23 74LS14, U5 Char, U19 LC3514, U18 4066

it was the character rom! finally after desoldering almost all but 2 IC's...

thanks Gerritt.

these 250469 boards are no fun to desolder, its like weld on there