Apple III obtained, cleaned, repairs

I obtained an Apple III and hard drive in late April 2026. Work to date was to clean the items, inspect, and perform repairs on the Apple III model monitor. A second AIII power supply was obtained along the way. This page was last updated May 18 2026(C) Herb Johnson all rights reserved. For other Apple II or Apple III items, check my Apple II parts pages.

Apple III cleaning

Apple III hardware

Power supply and a purchase from eBay

Apple III power supply as removed, RIFA has crack
Apple III, purchased power supply from seller May 2026
purchased power supply as received, supposedly working

Apple III logic, cabling

apple III logic as installed
logic, flat cables in place
cables removed from logic, to drive
view of cable in upper chassis

Apple III monitor repair

Apple III monitor, display before and after repair, Apr-May 2026

Apple III monitor, caps inspection
monitor inside chassis
monitor as obtained, single horizontal line
monitor after repair, no input, full vertical screen
monitor after repair, displays Apple IIe text

Gathering information, symptoms, diagnosis

Monitor displays single horizontal line in center. Brightness and contrast work OK.
Most likely problem in vertical circuits.
monitor inside chassis
notes from a YouTube, repair of arcade CRT monitors
From Apple III mon‭itor by Sams Photofacts, schematic - note IC 601 vert

Diagnosis identifies vertical chip IC601, chip extracted.

IC601 in monitor as obtained
IC601 before desoldering, note screw and pin near it
pinout of NTE1258
notes on cap measurements readings in circuit of capitance & resistance, cap readings out of circuit, values from schematic and cap markings
(Not shown, oscilloscope finds no vertical oscillation, so no vertical sweep.)
Resistance and capacitance results around IC601 suggest components OK, must be IC.
IC601 removed and tarnished, new part in foam on left.
a different GE1258 offered as "new" on ebay, note tarnish
IC601 pins desoldered, note fine solder debris

Vertical chip IC601 replaced and results.

IC601 soldered in, debris brushed out
IC601, new installed. Note grey glob of thermal paste at edge of heatsink.
After installation: monitor display fully vertical, see previous before/after descriptions.

The hard part of installing the IC was dealing with tarnish on the IC pins. Tarnish kept the solder from sticking. I would have filed or abraded the pins before, but lessons learned prior that subjecting IC's to fast repetative motions generate electrostatic charges that ZAP unprotected signal pins. A good example is Apple II keyboard decoders IC's, those fail often. So I scraped pins slowly with an Exacto knife. In the short term, inspection during soldering and good results after suggest connections on all pins. I hope all the solder joints are solid and not just contact-only, contacts will corrode and fail in time.

Herb Johnson
New Jersey, USA
here's how to email @ me and to order