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| Experience recap Performa 475 ... no video |
Posted by: franklyn on 2025-02-06 08:25:28
I soldered in/replaced new tantalum capacitors instead of the normal capacitors. Since then, the computer has booted normally from a floppy disk or from BlueSCSI, but there is no video. The monitor shows a frequency that is too high, but everything remains black. I don't think it's a capacitor replacement because I've had something like this before, but after a few keyboard resets, it worked again. I took out the VRAM and put it back in.
measured Hsync, Vsync, Sence0,1,2, they are between the monitor socket and the MEMCJR chip.
3.6V battery is new and good |
Posted by: franklyn on 2025-02-06 08:32:11
I added the CUDA reset button S1.
The problem was my two new 512kB VRAM modules from the internet that I had just bought and were suddenly no longer working. With my two old 256kB VRAM modules everything was fine again.
Re-solder the 512kB modules and see if they are OK again or not... |
Posted by: Andy on 2025-02-06 10:15:08
Do you have a battery installed? If you don't the 475 will not display video. You can try switching power off and then back on quickly to try and get around this sometimes. |
Posted by: imactheknife on 2025-02-07 20:01:03
Would reflow the caps you did and clean board really well. Definitely needs good vram to display anything |
Posted by: franklyn on 2025-02-08 12:47:08
... the two VRAM Simms are faulty.
I resolder the Simms and all works again. |
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