Jump to content

Atari SC1224 Capacitor Replacement Guide

From RetroTechCollection
The CA-3 chassis of the Goldstar-built SC1224, from Atari's service manual

The Atari SC1224 was built by JVC, Goldstar and Samsung, and each version has its own boards and capacitor list.[1] Service manuals survive for two of them: the Goldstar set on the CA-3 chassis and the JVC set that Atari calls Version 2. No parts list for the Samsung set has been found.

The monitor has a colour CRT with an anode supply of 22 to 23 kV and mains-connected primary circuits. Unplug it, discharge the CRT as described in CRT Discharge Procedure, and treat the power board as live until the reservoir capacitor has been measured at a safe voltage. Goldstar's manual requires an isolation transformer between the monitor and the mains when the chassis is serviced powered.[2]

Which version is it?

[edit | edit source]

The Version 2 board set is marked MA-1018A and has the brightness control on the back panel with the hold, height and position controls.[3][4] The CA-3 chassis has brightness and contrast at the front or side with the on/volume knob, and V-LIN, V-SIZE, V-HOLD, H-POSITION and H-HOLD at the back.[5] The photographs on the Atari SC1224 page show the two cases.

Goldstar CA-3 chassis

[edit | edit source]

Atari's CA-3 parts list gives every capacitor on the main, CPT (CRT) and power boards. The tables below list the electrolytic, non-polarised electrolytic (BP) and tantalum parts. Values and part numbers are from the parts list; three printing errors are corrected from the CA-3 schematic and the part numbering, and each correction is noted.[6][7][8] Shaded parts are, in Atari's words, components with "special characteristics important to safety"; replace them with the same type.[6]

CA-3 main board electrolytics
Ref µF Voltage Type Atari part no. Notes
C302 22 16 V Electrolytic 08110315
C304 22 16 V Electrolytic 08110315
C305 22 16 V Electrolytic 08110315
C306 22 16 V Electrolytic 08110315
C307 100 16 V Electrolytic 08110319
C308 1 50 V Non-polarised (BP) 181-064R
C312 22 16 V Electrolytic 08110315
C314 22 16 V Electrolytic 08110315
C315 22 16 V Electrolytic 08110315
C316 22 16 V Electrolytic 08110315
C317 100 16 V Electrolytic 08110319
C318 1 50 V Non-polarised (BP) 181-064R
C322 22 16 V Electrolytic 08110315
C324 22 16 V Electrolytic 08110315
C325 22 16 V Electrolytic 08110315
C326 22 16 V Electrolytic 08110315
C327 100 16 V Electrolytic 08110319
C328 1 50 V Non-polarised (BP) 181-064R
C331 100 160 V Electrolytic 02140719
C332 330 16 V Electrolytic 02140322 The A chart checks the 12 V supply at C332
C333 22 16 V Electrolytic 08110315
C401 1 50 V Electrolytic 08110507
C402 220 16 V Electrolytic 02140321
C403 10 16 V Electrolytic 08110313
C404 10 16 V Electrolytic 08110313
C406 1000 16 V Electrolytic 02140325
C409 220 16 V Electrolytic 02140321
C601 220 16 V Electrolytic 02140321
C602 10 16 V Electrolytic 08110313
C607 0.47 50 V Electrolytic 08110505
C608 1 25 V Tantalum 181-032J
C609 1000 25 V Electrolytic 02140425
C613 100 50 V Electrolytic 02140519
C614 100 50 V Electrolytic 02140519
C616 220 25 V Electrolytic 02140421
C617 3.3 25 V Non-polarised (BP) 181-098A
C618 47 25 V Electrolytic 08110417
C621 10 25 V Electrolytic 08110413
C703 1000 16 V Electrolytic 02140325 The parts list prints 100 µF; the schematic shows 1000/16, and the part number is the same as C406
C707 1 50 V Electrolytic 08110507
C709 1 50 V Electrolytic 08110507
C713 2.2 160 V Electrolytic 08110709 The C-1 chart checks for 23 V at C713
C719 33 50 V Electrolytic 08110516 Shaded (safety) part in the parts list
C721 2200 35 V Electrolytic 181-081H Shaded (safety) part in the parts list
C724 10 160 V Electrolytic 02140713 Shaded (safety) part in the parts list
C726 3.3 25 V Non-polarised (BP) 181-098A
C727 3.3 25 V Non-polarised (BP) 181-098A
C728 220 16 V Electrolytic 02140321
C729 100 16 V Electrolytic 08110319
C734 33 16 V Electrolytic 08110316 Shaded (safety) part in the parts list
C735 1 160 V Electrolytic 08110707 Shaded (safety) part in the parts list
C736 220 160 V Electrolytic 181-134A
C737 1000 25 V Electrolytic 02140425
C739 3.3 25 V Non-polarised (BP) 181-098A
C740 33 160 V Electrolytic 181-102A
C741 1000 25 V Electrolytic 02140425 Shaded (safety) part in the parts list
CA-3 CPT (CRT) board electrolytics
Ref µF Voltage Type Atari part no. Notes
C501 10 16 V Electrolytic 02110313
C504 10 16 V Electrolytic 02110313
C507 10 16 V Electrolytic 02110313
C511 10 160 V Electrolytic 02140713
C512 1 160 V Electrolytic 02110707
C513 1 160 V Electrolytic 02110707
C514 1 160 V Electrolytic 02110707
CA-3 power board electrolytics
Ref µF Voltage Type Atari part no. Notes
C950 120 400 V Electrolytic 181-124G Mains reservoir after the bridge BD901
C951 10 100 V Electrolytic 02140613
C952 10 50 V Electrolytic 02140513
C961 1000 25 V Electrolytic 02140425 14 V output filter. The parts list prints "1000pF"; the schematic shows 1000/25V and the part number is the same as C609
C963 1000 25 V Electrolytic 02140425 12 V output filter. The parts list prints "1000pF"; the schematic shows 1000/25V
C965 100 160 V Electrolytic 02140719 115 V output filter. The parts list prints "100pF"; the schematic shows 100/160V and the part number is the same as C331

That is 61 polarised electrolytics, seven non-polarised electrolytics (C308, C318, C328, C617, C726, C727 and C739) and one tantalum (C608) on the three boards.

The power board also carries film and ceramic capacitors that are not in these tables. C956 is a 0.047 µF 800 V polypropylene part; C901 and C902 are Panasonic ECQ-E2A104MW metallised polypropylene parts and C904, C905, C957 and C958 are safety ceramic parts, all shaded.[7] One owner of a dead SC1224 found C950, C961 and a capacitor numbered C966 leaking and heat damage on C956.[9] C966 does not appear in the CA-3 parts list, so that monitor may have had a different power board. On the main board the horizontal retrace capacitors C715 (printed 472, 4.7 nF, 1600 V), C716 (222, 2.2 nF, 1600 V) and C717 (102, 1 nF, 1250 V) are shaded polypropylene parts.[6]

JVC Version 2

[edit | edit source]

Atari's Version 2 parts list omits standard resistors and capacitors; it gives only the part-number code for a standard electrolytic of each voltage.[10] The values below are read from the schematic and the annotated circuit pages, with the parts list used where it gives the part.[4][11][12] Where the two disagree, both are given. The notes give the symptom Atari's circuit pages list for that part.[11]

Version 2 main board (MA-1018A 1/4) electrolytics
Ref µF Voltage Type Notes
C1002 3.3 16 V Electrolytic Clamp charge, red; open or short gives no red raster
C1003 3.3 16 V Electrolytic
C1004 3.3 16 V Electrolytic
C1005 100 25 V Electrolytic 12 V supply to IC1001 pin 16
C1101 100 25 V Electrolytic
C1201 100 25 V Electrolytic
C1301 100 25 V Electrolytic
C1105 0.47 50 V Non-polarised (BP) Parts list 0.47 µF; the schematic prints "47/50 BP"
C1205 0.47 50 V Non-polarised (BP) As C1105
C1305 0.47 50 V Non-polarised (BP) As C1105
C1106 10 16 V Electrolytic Pedestal clamp; short gives no red raster, open gives a red raster
C1206 10 16 V Electrolytic
C1306 10 16 V Electrolytic
C1151 4.7 50 V Non-polarised (BP) Parts list 4.7 µF; the schematic prints 3.3/50 BP
C1251 4.7 50 V Non-polarised (BP) As C1151
C1351 4.7 50 V Non-polarised (BP) As C1151
C1152 3.3 50 V Non-polarised (BP) Input coupling
C1252 3.3 50 V Non-polarised (BP)
C1352 3.3 50 V Non-polarised (BP)
C1402 2.2 16 or 50 V Tantalum or electrolytic (sources differ) V oscillator; open or short gives a single horizontal line. Parts list: tantalum 2.2 µF 16 V; schematic: 2.2/50 E cap ±20%
C1403 470 16 V Electrolytic Vcc smoothing; short gives a single horizontal line
C1407 33 25 V Electrolytic
C1423 100 35 V Electrolytic Boost (IC1421)
C1424 470 25 V Electrolytic
C1425 470 35 V Electrolytic
C1427 1000 25 or 16 V Electrolytic Side pin compensation; short gives side pin distortion. Schematic 1000/25; the parts list gives 1000 µF 16 V, so a 25 V part covers both
C1429 470 16 V Electrolytic Side pin compensation; short gives side pin distortion
C1452 4.7 50 V Electrolytic Vertical blanking (Q1451)
C1502 4.7 50 V Electrolytic Noise filter on IC1501
C1503 220 25 V Electrolytic
C1505 1 50 V Electrolytic H AFC smoothing; short gives faulty horizontal sync
C1508 100 16 V Electrolytic
C1522 1 160 V Electrolytic
C1523 33 160 V Electrolytic
C1530 10 25 V Electrolytic
C1531 470 25 V Electrolytic Filter after D1522, the 15 V (B2) rectifier
C1532 10 160 V Electrolytic HB rectifier
C1541 1 160 V Electrolytic Clamp; short shifts the raster to the right
C1551 1000 16 V Electrolytic Smoothing for the 16 V line
C1563 4.7 160 V Electrolytic HB regulator
C1564 10 160 V Electrolytic HB regulator
C1701 10 16 V Electrolytic B1 overvoltage detection; open gives no raster
C1702 100 25 V Electrolytic
C1703 10 35 V Electrolytic
C1807 33 25 V Electrolytic +15 V supply to IC1801
C1904 470 200 V Electrolytic Mains reservoir after D1901-D1904; shaded (safety) part
C1905 1000 25 V Electrolytic Starter supply after D1905
C1907 10 160 V Electrolytic Ripple filter (with R1906)
Version 2 audio board (MA-1018A 3/4) electrolytics
Ref µF Voltage Type Notes
C1601 1 50 V Electrolytic Input coupling; short gives no sound
C1602 220 16 V Electrolytic
C1603 10 50 V Electrolytic Short gives no sound
C1604 10 50 V Electrolytic Open gives no sound
C1607 220 16 V Electrolytic
C1610 1000 16 V Electrolytic 16 V supply smoothing
Version 2 CRT socket board (MA-1018A 2/4) electrolytics
Ref µF Voltage Type Notes
C1081 100 25 V Electrolytic
C1311 4.7 160 V Electrolytic Schematic 4.7/160; the parts list gives 10 µF 160 V

The Version 2 has nine non-polarised electrolytics, all in the RGB input and drive stages (C1105, C1151, C1152 and their green and blue equivalents). Fit bipolar parts there. An owner who recapped an SC1435 warns against fitting a polarised part in a non-polarised position.[13] The shaded film capacitors C1526 (7200 pF 1600 V) and C1534 (5600 pF 1600 V) set the horizontal retrace; Atari lists them as metallised polypropylene parts with a ±3 % tolerance.[12] An open C1526, C1534 or C1535 makes the picture narrow, and an open C1529 (the 0.3 µF 200 V S-correction capacitor) leaves a single vertical line.[11]

Procedure

[edit | edit source]
  1. Unplug the monitor and remove the rear cover. On the Version 2 it is held by five screws.[14]
  2. Discharge the CRT anode to the chassis earth and keep a lead on it while working. See CRT Discharge Procedure.
  3. Measure the mains reservoir (C950 on the CA-3, C1904 on the Version 2) and discharge it through a resistor if it holds a charge.
  4. On the Version 2, remove the main board: two screws (B), two screws (C) and two screws (D), the bracket if needed, the anode lead and the other wires. Keep the CRT earth wire connected between the CRT socket board and the main board whenever the set is powered for checks, and coat the CRT socket with silicone grease if it is disconnected.[14]
  5. Replace one capacitor at a time. Match polarity to the board marking, keep at least the voltage in the tables, and fit bipolar parts in the BP positions.
  6. Fit shaded (safety) parts with the type the parts list gives.[6][10]
  7. While the board is out, inspect the solder side and resolder dry joints. A monitor repairer on Atari-Forum advises going over every joint before replacing parts.[15]
  8. Refit the board, reconnect the anode cap and the CRT earth, and run the checks below.

Checks after recapping

[edit | edit source]
Supply checks
Version Point Expected
CA-3 Power board outputs P962, P961, P960 115 V, 12 V, 14 V[8]
CA-3 FBT pin 7 and point A10 115 V[16]
CA-3 Sound IC pin 1 and pin 9 12 V and 14 V[16]
CA-3 CRT heater, H1 to H2 About 6.3 V rms[16]
Version 2 B1 line, IC1901 pin 4 125 V[17]
Version 2 HB line 120 V, set with HB ADJ R1570 after a 30-minute warm-up[18]
Version 2 IC1421 pin 3 25.3 V[19]
Version 2 IC1601 pins 7 and 9 11.8 V and 14.1 V[19]

Goldstar's manual says the CA-3 has no high-voltage adjustment and that the 115 V supply must be correct for the high voltage to be correct; it gives 23.0 kV as the nominal anode voltage, 24.0 kV as the limit at zero beam current and 24.5 kV under any setting of the brightness control.[2][20] Measure the anode voltage only with a high-voltage probe made for it.

[edit | edit source]

References

[edit | edit source]
  1. ↑ "Atari SC1224 RGB Color Monitor", atari-computermuseum.de, https://www.atari-computermuseum.de/st_peri.htm#sc1224. Secondary source for the three manufacturers.
  2. ↑ 2.0 2.1 Atari, SC1224 RGB Color Monitor Service Manual, chassis CA-3, Safety Precautions (PDF p. 6). File:Atari SC1224 Service Manual (CA-3 chassis).pdf.
  3. ↑ Atari Corporation, SC1224 Version 2 Field Service Manual, C070433, February 1986, Functions, p. 4. File:Atari SC1224 Version 2 Field Service Manual C070433.pdf.
  4. ↑ 4.0 4.1 SC1224 Version 2 Field Service Manual, Schematic Diagram (PDF p. 32).
  5. ↑ SC1224 Service Manual (CA-3), Control Operation, printed p. 5 (PDF p. 7).
  6. ↑ 6.0 6.1 6.2 6.3 SC1224 Service Manual (CA-3), Replacement Parts List, main board capacitors, printed pp. 30-31 (PDF p. 21).
  7. ↑ 7.0 7.1 SC1224 Service Manual (CA-3), Replacement Parts List, CPT and power boards, printed p. 32 (PDF p. 22).
  8. ↑ 8.0 8.1 Atari, CA-3 Chassis Schematic Diagram, P/N 484-257A. File:Atari SC1224 CA-3 Chassis Schematic and Troubleshooting Charts.pdf, PDF p. 1. Source for C703 (1000/16), C961 and C963 (1000/25V), C965 (100/160V) and the output voltages.
  9. ↑ "Dead SC1224", Atari-Forum, posts by MaLICiouS, 26 March 2010. https://www.atari-forum.com/viewtopic.php?t=18975. Community report.
  10. ↑ 10.0 10.1 SC1224 Version 2 Field Service Manual, Replacement Parts List Information, p. 11.
  11. ↑ 11.0 11.1 11.2 SC1224 Version 2 Field Service Manual, annotated circuit pages, pp. 23-30.
  12. ↑ 12.0 12.1 SC1224 Version 2 Field Service Manual, Replacement Parts List, p. 12.
  13. ↑ "Atari SC1224", exxos's Atari, Amiga & retro forum, post by derkom, 21 May 2020. https://www.exxosforum.co.uk/forum/viewtopic.php?t=2803. Community report.
  14. ↑ 14.0 14.1 SC1224 Version 2 Field Service Manual, How to Remove for Service, p. 5.
  15. ↑ "Faulty sc1224 and Sc1436?", Atari-Forum, post by simbo, 28 February 2007. https://www.atari-forum.com/viewtopic.php?t=10579. Community advice.
  16. ↑ 16.0 16.1 16.2 SC1224 Service Manual (CA-3), troubleshooting charts A, B, C, C-1 and K, printed pp. 11-14 and 20 (PDF pp. 12-14 and 17).
  17. ↑ SC1224 Version 2 Field Service Manual, Power Circuit, p. 29.
  18. ↑ SC1224 Version 2 Field Service Manual, Service Adjustments, pp. 6-7.
  19. ↑ 19.0 19.1 SC1224 Version 2 Field Service Manual, Trouble Shooting, problems 3 and 4, pp. 20-21.
  20. ↑ SC1224 Service Manual (CA-3), Adjustment and Maintenance, High Voltage Check, printed p. 6 (PDF p. 8).


Retrieved from "https://wiki.retrotechcollection.com/index.php?title=Atari_SC1224_Capacitor_Replacement_Guide&oldid=24010"