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| bLANK SCREEN ON POWER UP. | cHECK eXTERNAL pOWER sUPPLY u4 (kernal rom), u17 (pla) u7 (6510 mpu), u3 (rom) u8 (7406 ic), u19 (vic ii) u9-u12 (4164 ram) u21-u24 (4164 ram) bt2, cr4, vr1 |
| oUT OF MEMORY ERROR ON POWER UP. | cHECK u9-u12 (4164 ram)
u21-u24 (4164 ram) **** use diagnostic test - disk |
| nO CURSOR DISPLAYED. iNTERMITTENT BLANK SCREEN. | cHECK u1, u15, u7 cHECK u2, u7 |
| pOWERS UP WITH GRAPHICS DISPLAY AND BLINKING CURSOR | cHECK u14 (74ls258 ic) |
| pOWERS UP WITH ALL THE CHARACTERS DISPLAYED AS BLOCKS. | cHECK u26 (74ls373 ic) |
| iNTERMITTENT DISPLAY. | cHECK c88 (pOSSIBLE bAD cONNECTION) |
| pOWERS UP WITH THE 'press play on tape' MESSAGE AND THE DISPLAY BLANKS | cHECK u7 (6510 mpu)
r1 (pOSSIBLE bAD cONNECTION) |
| oN POWER UP THE CURSOR LOCK UP. | cHECK u7 (6510 mpu)
u20 (556 ic) |
| wHEN 'return' IS PRESSED AFTER A RUN COMMAND, THE CURSOR GOES BACK TO HOME POSITION. | cHECK u3 (rom) |
| pOKE COMMAND DOES NOT WORK. | cHECK u3 (rom) |
| jOYSTICK DOES NOT OPERATE CORRECTLY. | cHECK u1, u28 (6526 cia) |
| wRONG FREQUENCY. | cHECK c70 |
| nO CHARACTER LETTERING IS DISPLAYED ON THE SCREEN. | cHECK u3 (rom)
u2 (cia) |
| gRAPHIC CHARACTERS INSTEAD OF LETTERS DISPLAYED. | cHECK u19 (vic ii) |
| pOWER UP MESSAGE APPEARS BUT NO CURSOR. | cHECK u1, u15, u7 AND u4 |