Toshiba HX-10

Supporter (16)

11-12-2020, 17:09

Need help with a black screen HX-10,i dont know how to move forward with troubleshooting.

*Have changed Bios Rom for one with verified content.
*Changed LVA510 video chip, no difference
*Keyboard sounds when keys are pressed and capslock light works
*typing 10 Beep 20 goto 10 run program works and it starts beeping so i think CPU, EPROM and so on is ok.
*voltages on 4116 ram chips have been checked ( +5, -5, 12v all there) voltages seems ok all over board.
*cartrige or no cartridge makes no difference.

Any ideas?

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Van st1mpy

Paladin (947)

11-12-2020, 17:32

Is it connected by RF or composite? Have you tried both?

Van RetroFletch

Supporter (16)

12-12-2020, 11:54

Only composite

Van st1mpy

Paladin (947)

13-12-2020, 13:55

If RF also gives the same result, how about writing a test program to test the vdp? (Assuming you've checked the vdp is still alive/powered and it just isn't just solder/socket issue by re-seating. And the vrams are ok as well.) May be something short to write something into vram and read back to compare and confirm with a beep, or a sprite collision test.