Commodore 1084 S-D1 Service Manual page 11

As major parts of this chassis employ ICs, defects can often be isolated by referring to the table of symptoms іп
Table 1. Additional checks of transistor and IC, DC voltages and waveforms as shown on the schematic will assist
in pinpointing the problem area. Remember also to check for faulty resistors and capacitors, etc. around defective
155 and transistors.
IC/TR
1101: POWER SUPPLY CIRCUIT
1201: HORIZ OSC, DRIVE, SYNC SEP CIRCUIT
1202:
1301:
1401:
SYNC PROCESSING CIRCUIT
VERT OSC, OUTPUT CIRCUIT
VIDEO PREAMP, COMPOSITE COLOR MATRIX,
MODE SWITCHING RGB AND COMPOSITE
SIGNAL, AUTO OUT-OFF CONTROL
CIRCUITS
12V REGULATOR
5У REGULATOR
COMPOSITE COLOR CIRCUIT
MODE SWITCHING CIRCUIT
1402:
1403:
1601:
1602:
1701, 1702: TTLI CIRCUIT
1801, 18011: STEREO SOUND CIRCUIT
Q201: HORIZ DRIVE CIRCUIT
Q202: HORIZ OUTPUT CIRCUIT
Q203: SYNC SWITCHING CIRCUIT
Q601: COLOR INPUT BUFFER CIRCUIT
: COMPOSITE BUFFER CIRCUIT
‚ Q702, Q703: TTL BUFFER
Q704: TTL COLOR MATRIX CIRCUIT
Q501-Q504: R OUTPUT CIRCUIT
Q505-Q508: G OUTPUT CIRCUIT
Q509-Q512: B OUTPUT CIRCUIT
SYMPTOM
NO RASTER
NO RASTER, NOPICTURE, NO HIGH VOLTAGE
UNSTABLE PICTURE
RGB MODE UNSTABLE PICTURE
HORIZONTAL LINE ONLY, POOR VERTICAL SCAN
NO PICTURE OR POOR PICTURE, NO AUTO
CUT-OFF CONTROL, NO MODE SWITCHING OF
COMPOSITE AND RGB SIGNAL
NO PICTURE OR POOR PICTURE
RGB MODE NO PICTURE, POOR PICTURE
NO COLOR, UNSTABLE COLOR
NO MODE SWITCHING, NO PICTURE,
UNSTABLE PICTURE
TTL RGB MODE. NO PICTURE. POOR PICTURE
NO SOUND OR POOR SOUND
NO PICTURE, NO HIGH VOLTAGE
RGB MODE, UNSTABLE PICTURE
NO COLOR, POOR COLOR
COMP/SEP MODE, NO VIDEO OR POOR VIDEO
TTL MODE, NO PICTURE OR POOR PICTURE
TTL MODE, NO BROWN COLOR, OR UNSTABLE
COLOR
NO RED PICTURE
NO GREEN PICTURE
NO BLUE PICTURE
TABLE 1.