Services performed on all items:
Switches and controls are cleaned, as needed.
All burned out indicator and illumination lamps are replaced.
All inputs, outputs and functions are tested.
FM tuners are aligned for maximum sensitivity, maximum separation, minimum distortion and correct dial calibration.
Amplifiers are tested for rated power output, distortion and noise. The DC offset and bias are checked and adjusted.
Any necessary repairs or modifications are performed.
Services performed on Reel to Reels and Cassettes:
All belts and rollers inspected and replaced as necessary.
Mechanisms repaired, lubricated and adjusted as necessary.
Tape path cleaned and demagnetized.
Tape speeds checked and adjusted.
The following ELECTRICAL adjustments are made for EACH channel:
Playback level (all speeds).
Playback equalization (all speeds).
Playback meter calibration.
Record sensitivity level (all speeds).
Record equalization (all speeds).
Record meter calibration.
Bias adjustment (all speeds and bias settings).
Finally, a frequency response test is performed of the record/playback performance and is published with the ad.
Special note regarding Nakamichi cassette decks:
These are truly fine tuned instruments that require skill in servicing.
We have been servicing Nakamichi decks since the early 1980's and have a full complement of factory service manuals, test tapes and alignment jigs.
'The Bench' consists of laboratory grade test equipment manufactured by Sound Technology. This includes the Sound Technology model 1700B and 1701A distortion measurement systems, Sound Technology model 1000A FM alignment generator with the Sound Technology model 1100 signal conditioner and the Sound Technology model 1200A stereo test panel. Also at hand are the Marantz MTP-400 4 channel test panel and the Nakamichi T-100 audio analyzer.
Beware of amateurs! Do not trust vague terms such as "re-capped", "O'scoped" or "checked by tech." The need for qualified service has been acknowledged by the market. There are many hobbyists claiming to be "experts". Demand proof of service from a qualified repair facility.
Unfortunately, there are many legitimate shops that are not qualified to service vintage audio. We recommend that you do not buy from, or accept service from, any entity that cannot perform these basic tests.
Our owner, Tim Whyte, worked for many years in the service department of Century Stereo, was the service manager at Paradyme Sound and Vision, and is an SBE Certified Radio Broadcast Engineer.
This is an example of pre-mature clipping of one half of the output waveform of an amplifier. Note the flattening of the bottom of the sine wave in the top scope trace. The amplifier under test is rated at 50 watts RMS into 8 ohms. The problem occured at around the 40 watt level, and only in one channel. The bottom trace, which should be a flat line, is the distortion component. This type of problem CAN NOT be found with listening tests. In fact, this item was acquired with the understanding that it worked perfectly, and was used in a system for some time. The problem was discovered during routine performance tests prior to
offering the unit for sale by classicaudio.com
Nice clean waveform, right? WRONG! The picture below includes the distortion component waveform.
The amp, rated at 125 watts per channel, produced over 2% THD at 1 watt.
Many people ask us how hard it is to clean switches and controls. The level of difficulty depends on the brand and model being serviced.
The model pictured above (a Pioneer SX-1050) was slightly above average in difficulty.
The switches and/or controls must be accessed from the rear.
Attempting to apply cleaner from the front rarely works.
In order to get to the function selector switches the front panel had to be removed.
Then the board below the target board had to be removed.
Finally, the function switch board was able to be removed and the switches cleaned.
Yes, it can be a considerable amount of work to clean a switch correctly.
And finally, a few truths to ponder:
"Soldering is easy, science is not."
"The simpler a device, the longer it will remain trouble free."