A selection of recent repairs and restorations
8- and 16-bit era hardware, restored to working order
Display showed columns of garbage characters ("??" and "@@"). Traced fault to a bad IC socket for the 9334 character ROM. Replaced socket. Installed ROMX and preserved original ROM chips.
CompletedReceived with a non-booting hard drive and request to perform maintenance. Conducted full recap of both the analog (Rev B) and digital (Rev A) boards, including cleanup of leaking electrolyte from the logic board. Replaced the original 1991 PRAM battery. Performed repair on stuck hard drive read head.
CompletedDisk stuck in internal floppy drive; external floppy unable to read and format reliably. Disassembled and cleaned both drives, replaced broken eject gear in internal floppy, and repaired a failed 2SB624 transistor preventing ejection. Copied owner's files off legacy HD20 hard drive, reinstalled MacOS 6.0.8, and restored original files. Reflowed solder joints on analog/logic board connectors to correct flickering of display.
CompletedWhite screen on boot with "motorboat" audio noise. Verified 68000 clock and control signals; reseating and cleaning all socketed ICs with DeOxit restored boot to desktop. Sourced correct keyboard cable, cleaned sticky key contacts, and confirmed floppy disk formatting.
CompletedReceived for assessment and repair. Replaced leaking/failed electrolytic capacitors and rebuilt RF modulator unit. Identified failed 74LS541 ICs preventing controllers from functioning; parts pending order.
In ProgressStereo receivers, integrated amplifiers, and playback equipment
All resistors tested in-spec. Identified electrolytic capacitors requiring replacement including high-voltage axial and radial caps up to 500 WV. Tubes tested; one 6L6 has an intermittent grid short. Replaced tube, set bias, and tested.
CompleteReplaced underperforming power supply filter caps and both pairs of failed output transistors (2SB617/2SD587 → MJE15033G/MJE15032G); modified heat sink to accept TO-220 packages. Diagnosed loud crackling at power-on; identified failed 2SC1735 driver transistor, further output stage diagnostics in progress.
In ProgressLow/no volume on right channel traced to a dirty rear-panel gain switch. Cleaned all pots and switches with DeOxit and verified both channels. Also repaired switched AC outlets — a wire to the power switch had come unsoldered.
CompletedReplaced failed power supply filter capacitors, cleaned all pots and switches, and repaired and reinstalled the FM antenna. Performed realignment. Full functionality confirmed.
CompletedNo audio output. Cleaned HDMI board and reflowed IC with known cold solder joint issues. Audio fully restored.
CompletedNo output on Channel A; Channel B output only on right. Traced fault to a dirty balance pot. Cleaned all pots with DeOxit; full stereo output restored.
CompletedNo power-up despite drawing current and passing 120 VAC through rear outlets. Located a blown RD24E(B) zener diode (ZD601) on the protector circuit board. The 28 V rail powering the protection circuit is absent despite the transformer primary receiving mains voltage — further diagnosis in progress.
In ProgressTube PA amplifier recapped. Working well after service. Noted that "line" speaker socket pins must be jumpered for the AC power to function correctly.
CompletedSpeaker plug had been soldered directly into socket with wires detached. Replaced failed filter caps (arcing noted before removal), several non-original wax paper tube caps, and two open Candohm wirewound resistors. Cleaned audio potentiometer and rewired speaker correctly per schematic.
CompletedSeveral capacitor and transistor legs hadn't been soldered during an apparent previous restoration attempt. Identified and soldered all unsoldered leads, reviewed all components on board, verified functionality.
CompletedOptical drive mechanisms and playback systems
Carousel misaligned by approximately one disc position; required a nudge to load. Visibly worn and stretched drive belts caused intermittent "Table Error." Replaced table and loader belts, realigned carousel and disc detector. Loading issue fully resolved.
CompletedCD tray would not open (but closed fine when manually pushed in). Located and replaced two faulty transistors (BC338, BC328) and two axial electrolytic caps on the control board. Disc tray operation improved; further recapping may be warranted.
CompletedFailed to read certain disc types reliably. Adjusted the laser gain potentiometer approximately 10–15° clockwise until correct values obtained on 'scope. Unit now reads all disc types tested except DVD-R.
CompletedNo power. Found a 2200 µF / 16 V electrolytic in the power supply installed backwards during a prior restoration. Correctly oriented and replaced the capacitor; unit powered up normally.
CompletedHF receivers, transceivers, and RF amplifiers
Band switch frozen; fan seized; zero plate current; unit wired for 220 V. Freed band switch with heat and penetrating oil, freed and lubed fan, located three open rectifier diodes in the HV power supply (subbed 1N4005), and rewired input block for 120 V. Pending components for a complete power supply rebuild and meter protection modification.
In ProgressNo reception and loud pops when tuning. Cleaning pots and switches with DeOxit did not resolve the issue. Replaced the main 4-section electrolytic capacitor and performed realignment. Reception fully restored.
CompletedNo audio beyond faint scratches and pops. Replaced power supply filter caps and other electrolytics; replaced weak 6EB6 tube. Unit now functions, though alignment is likely needed for optimal performance (customer declined alignment).
CompletedControl head cable connector was physically torn off, shorting B+ across all conductors. Found melted/destroyed ferrite bead FB1762 and shorted zener D1754 on the main board. Bypassed FB1762, replaced zener with equivalent, and confirmed restored operation.
CompletedReceived for evaluation. Tested receive and CW transmit; approximately 100 W output confirmed. Unit functional on all tested bands.
Evaluated & ReturnedFM section non-functional: magic eye tube not lighting, zero FM input signal, AM and Aux modes work. Some audio bleed-through from Aux on FM. Scratchy pots. Diagnosis in progress.
In ProgressAutomotive audio, test equipment, and more
Meters functional but no display on the CRT. Located burned resistor R6 and a leaking high-voltage film cap in the power supply. Temporary bypass confirmed CRT operation, but large clamp-mount electrolytics testing poorly may be causing too much current to pass through R6. Metal rectangular PIO caps also suspect. Active repair in progress.
In ProgressNo movement despite powering up. Reflowed ICs and cleaned and relubricated the tonearm. Tonearm now lifts and seeks as expected. Table requires careful leveling to function properly.
CompletedAmplifier producing only low-frequency audio. Per known repair procedures for this unit, identified electrolytic caps and four N-channel MOSFETs (IRFIZ34G) for replacement. Repaired and functionality restored.
CompleteOptiScale Technologies, LLC
Located in Southern California — serving customers nation-wide