Editing Apple AppleVision 850 Display (section)

== Known faults ==
* Apple's service manual notes that many modules returned for repair worked, and puts set-up, software and environmental checks first.<ref name="ssts">''20" ColorSync Displays'' Service Source, Troubleshooting, First Checklist and Symptom Charts, pp. 2-9 (PDF pp. 43-50).</ref>
* A screen that freezes at startup, and corrupted set-up data, can be caused by the yoke wires to BF1 and BL1 on the main deflection board being clamped in with the ribbon cables.<ref name="ssts" />
* One owner's 850AV would only display properly at 1024 × 768 and 60 Hz, giving a narrow, distorted picture in other modes; capacitors, the sync processor (a TDA4858 on the neck board) and its supply were checked without curing it. Another owner with an AppleVision 1710 found a similar fault in the control logic on the neck board and cleared it with new capacitors in the digital section and a blank 93C66 EEPROM, after which the display behaved as a plain multiple-scan monitor.<ref name="td2081">{{cite web |url=https://tinkerdifferent.com/threads/applevision-850av-repair.2081/ |title=AppleVision 850AV Repair |publisher=TinkerDifferent forum (Elemenoh, marmotta and others) |date=2022-11 to 2024-01 |access-date=2026-10-02}} Community repair thread with a capacitor list for the main deflection board.</ref>