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Atari SC1435 Capacitor Replacement Guide

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Main and CRT panels of the SC1435 with the adjusting components (service manual)

Electrolytic capacitors in the Atari SC1435 14-inch colour monitor, read from the electrical parts lists in its Philips-format service manual. The manual covers a 220-240 V model and a 110-120 V (USA) model; the parts that differ are marked in the list and in the tables below.[1]

The SC1435 has a 25 kV anode supply and a switch-mode power supply whose primary side is at mains potential (marked "hot ground" on the diagram and "life part" on the board). Unplug the monitor, discharge the CRT as described in CRT Discharge Procedure, and check that the mains reservoir 2412 is discharged before working on the main panel.[2][3][4]

Reading the parts list

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The parts list gives each capacitor with its Philips twelve-digit part number and its value. The parts rated in microfarads have 4822 124 or 5322 124 numbers, and all of them are in the tables below. The 4822 121 and 4822 122 series parts in the same list are film and ceramic capacitors rated in nanofarads or picofarads, apart from three printing oddities: 2402 is a 1 µF 275 V film part (5322 121 series), and 2407, 2409 and 2410 (4822 122 series) are printed "2,2µF 1kV" beside 2408, a 2.2 nF 1 kV part.[1] In this manual capacitors are numbered 2xxx, resistors 3xxx, coils and transformers 5xxx, diodes 6xxx and transistors and ICs 7xxx.[1]

Main panel

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SC1435 main panel, capacitors rated in µF
Ref µF Voltage Philips part no. Notes
2266 4.7 25 V 4822 124 41659
2268 2.2 63 V 4822 124 42166
2269 22 50 V 4822 124 23129
2272 22 50 V 4822 124 23129
2274 100 16 V 4822 124 22678
2291 1000 16 V 5322 124 10623
2301 22 50 V 4822 124 23129
2361 10 50 V 4822 124 23131
2412 100 400 V 4822 124 21722 220-240 V model. Mains reservoir
2412 220 200 V 4822 124 10531 110-120 V model
2416 10 50 V 4822 124 23131
2422 1 50 V 4822 124 22669 220-240 V model; the 110-120 V model fits a 470 nF 63 V film part here
2445 470 35 V 4822 124 41865
2446 470 25 V 4822 124 22357
2447 470 25 V 4822 124 22357
2450 10 50 V 4822 124 23131
2451 47 200 V 4822 124 41281
2452 22 50 V 4822 124 23129
2511 2.2 63 V 4822 124 22672
2512 22 50 V 4822 124 23129
2515 1 250 V 4822 124 41867
2520 10 160 V 4822 124 22499
2524 4.7 50 V 4822 124 90034 Printed as "4MU7"
2526 1 50 V 4822 124 22669
2536 1 50 V 4822 124 22669
2537 22 50 V 4822 124 23129
2541 22 50 V 4822 124 23129
2547 2.2 63 V 4822 124 22672
2560 22 35 V 5322 124 41431
2561 22 35 V 5322 124 41431
2563 470 35 V 4822 124 41865
2571 680 35 V 4822 124 41866
2573 1.5 63 V 4822 124 41975
2640 100 16 V 4822 124 22678
2647 4.7 25 V 4822 124 41659
2669 10 50 V 4822 124 23131
2696 47 16 V 4822 124 22681
2697 47 16 V 4822 124 22681

On the 220-240 V model that is 37 parts; on the 110-120 V model 2412 is the 220 µF 200 V part and 2422 is a film capacitor, so 36. The 2412 is the reservoir after the mains bridge 6407 to 6410.[3]

CRT panel

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SC1435 CRT panel, capacitors rated in µF
Ref µF Voltage Philips part no. Notes
2136 4.7 200 V 4822 124 22023
2141 22 50 V 4822 124 23129

Non-polarised part

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An owner who recapped an SC1435 reports that one of its capacitors is non-polarised, and warns against fitting a polarised part in its place.[5] The parts list does not mark polarity. Check the marking on each original part, and the schematic, before fitting a polarised replacement.

Procedure

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  1. Unplug the monitor and remove the rear cover.
  2. Discharge the CRT anode to the chassis earth (CRT Discharge Procedure).
  3. Measure the voltage on 2412 and discharge it through a resistor if it holds a charge.
  4. Replace one capacitor at a time. Keep at least the voltage rating in the tables; match polarity to the board marking; fit a non-polarised part where the original is non-polarised.
  5. Replace parts marked with the warning triangle in the parts list with identical parts, as the manual requires.[6]
  6. Never change parts with the set switched on.[6]
  7. After the work, set the +128 V supply with preset 3414 (see Atari SC1435 General Maintenance) before any other adjustment.[6]

Checks after recapping

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Supply check
Point Expected Adjust
Junction of 3520 (printed 3524 in the next step) and diode 6453 128 V DC with volume, brightness and contrast at minimum Preset 3414[6]

The adjustment text names the measuring point as the junction of resistor 3520 and diode 6453, then as junction 3524/6453 in the next step; the location drawing shows 3520 next to 6453 with the label "MP 128V".[6][4]

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References

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  1. ↑ 1.0 1.1 1.2 SC1435 service manual, Electrical parts CRT panel and Electrical parts main panel, PDF pp. 8-9.
  2. ↑ 14" CGA Colour monitor SC1435 service manual, Consumer Electronics (Philips), 4822 727 18351, Technical data, PDF p. 2. File:Atari SC1435 Service Manual.pdf.
  3. ↑ 3.0 3.1 SC1435 service manual, Power supply circuit diagram (on main panel), 110 V, PDF pp. 25-26.
  4. ↑ 4.0 4.1 SC1435 service manual, Location of adjusting components, PDF p. 22.
  5. ↑ "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.
  6. ↑ 6.0 6.1 6.2 6.3 6.4 SC1435 service manual, Caution and Electrical adjustments, PDF p. 3.


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