I thought that. It's white like in the picture..
Now I am stuck
Worst is that was fine, with very bad video.. but board was working.. I can't stop wondering wht did I do?
I thought that. It's white like in the picture..
Pin 3 is the inverted write enable, so it should be high normally and pulse low when the Z80A tries to write to the DRAM.
It’s possible that either the Z80A is not trying to access any memory where A11 is required to be high. Or that the Z80A chip is faulty or that there is another chip that has a fault and is dragging down the logic level (excessively loading the A11 line).bola_dor wrote: ↑Mon May 24, 2021 1:39 am A11 line pulses but very low.. in a TTL logic I think is always down. I checked its values in every IC and is always the same. Folowed the line across the board to the back connector and found nothing.. I 've been working in that area so I looked twice every thing. And still I didn't found anything.
But still I don't know if this is normal or not. or what can be causing it.
Yes I've been there.. I think I've learned some tricks destroying some tracks. I ve been successful some other times. I wish I have a hot air soldering station..Tiger wrote: ↑Wed May 26, 2021 9:01 am sorry to say that, but without skills in soldering it is very easy to destroy the fine lines between the IC pin's. Most "RAM upgraded" or "ROM replaced" ZX Spectrum's which I bought had this kind of faults. Sockets where soldered and soldering lines under this socket where shortened or broken.
I think you have a damaged ROM or CPU (maybe both damage by a bad connection over the expansion port)...