Our thorough Quad 33 service includes: Fault diagnosis, replacement of all electrolytic capacitors, out of tolerance components and a full performance test, PAT* and 48 hour soak test**. In some isolated cases where expensive or hard to procure parts are required, such as replacement switch banks, there will be an additional charge. If this arises we will notify you before we commence any further work.Standard 33 full service exampleThis particular 33 has noisy controls, hiss on the right channel and a low hum on both channels when set to 'disc'. In addition, the mains filter capacitor is burnt out, the 'radio 1' PB switch is intermittent and the left channel is cutting in and out spasmodically. The indicator bulb is blown. •Action Taken: First, the PCBs are removed and the PSU sub assembly is dismantled, thus allowing access to the PSU board and blown mains filter and the indicator lamp. •Full set of electrolytics (21 originals) and mains filter are then de-soldered and replaced with new devices.•A new legend lamp is fitted. •The volume, tone and filter control wipers and tracks are cleaned using a high performance switch cleaner.•With the oscilloscope set to 2mV/cm, the hiss on the right channel is clearly visible at the output of the tone control section but normal (no hiss) on the input side. Transistor, TR401 is the culprit and is replaced with a low noise BC549C. •On close inspection of the Left PCB a dry joint on C403 is clearly visible. This is the cause of the intermittent left channel. The faulty joint and the corresponding joints on both boards are re-soldered for good measure. •After removing the front of the chassis and releasing the bottom PCB, the push button channel selector switch bank is dismantled and the individual fixed switch contacts and minute slider bars are cleaned. This is a tedious and lengthy procedure but essential for reliable switch operation. •A Flat & RIAA frequency response and distortion test is carried out on the spectrum analyser and everything looks good on all inputs apart from a preponderance of 50Hz harmonics (spikes) on the RIAA test. Lifting the 33 clear of the bench the spikes fall to a more acceptable level. The cover is fitted, and the peaks drop to the correct level.•The 33 is carried over to the soak test area and hooked up to the record deck, CD player, FM4 tuner and monitor speakers. Listening in turn to familiar sources the overall sound quality is judged. •Satisfied with sound quality the 33 is left running for several hours. At the end of the soak a 'portable appliance safety test' (PAT) is carried out. We now contact you to announce a successful completion.