Processes

While each type of equipment (such as amplifiers and tape decks) would have different processes for repair and restoration, here’s a typical example of the process followed for examining a valve amplifier.

• Visual inspection of the top and bottom of , bottom cover off. Look for burnt resistors, leaking capacitors, open primary and secondary fuses, defective thermistor, defective rectifier diodes and other defective components etc., visually and electrically.
• Power the amplifier up in slow stages, with a Variac, to avoid shocking older electrolytic in the power supply, and to allow them to reform.
• Check all power supply voltages at the specified operating line voltage, according to manufacturer specifications
• Check all resistances at tube pins (when specified by manufacturer)
• Check All Electrolytic Capacitors for ESR (Quality), and Value using a Capacitor Analyzer
• Check audio coupling capacitors for leakage, quality and value
• Check all vacuum tubes on a calibrated Hickok tube tester
• Check bias current for all output tubes to ensure they are within normal range
• Check condition of input jacks and output terminal strips
• Check condition of switches and potentiometers
• Check for signal throughput and condition of output transformers – inject 1Khz signal at each channel input and check for output at each channel’s speaker terminals (loaded at 8 ohms). Check output transformers for continuity and winding shorts.
• Measure Output Power into 8 Ohm Loads.
• Measure sensitivity for full power output.
• Measure Channel Balance.
• Measure distortion (THD) @1Khz, half and full power output.
• Measure frequency response (20Hz,40hz, 100h,250Hz,500Hz,1Khz,5Khz,10Khz,15Khz,20Khz,25Khz 30Khz).
• System listening test – Assess quality of sound
• Issue Final Report to customer by Email or Call