Adjustments, ArrrrTl, GK 6 | Pioneer SX-3800 manual

8 . ADJUSTMENTS

8 . 1 F MT U N E R FM Tracking

rConnectthe SIGNAL meter or DC voltmeter

betweenR100 (no.? pin of Q8) on the tuner assemblyandground.

rThe tuning coil in the RF amplifier circuit does not have an adjusting core. Consequently, tracking adjustment at 90MHz are performed by regulating the gap between rotor and stator of

the tuning capacitor (VC3). The expression "adjust VC" found in the text means that the two outer rotor bladesof eachof thesetun- ing capacitorsare to be extended outwards with spatula(Part No.GGK-066)asshown in Fig.8-1.

Botor blacle

SpatuIa

( G GK . 0 6 6 )

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Fig . 8 - 1 Adjustmentof tuning capacitor

1 . Set up the test equipmentasFig.8-2.

2 . Set the FM MUTING switch to OFF, and FUNCTION switch to FM.

i J . Tune the SX-3800dial pointer to 106MHz.and set the FM SC (FM signal generator) output frequency to 106MHz, output level to 60d8, modulation frequency 400H2,frequency devia- tion 75kHz (100Vomodulation).

Adjust the TC1 (OSC trimmer) to obtain maxi- mum deflection of the signalmeter.

5 . Then tune the dial pointer to 90MHz, and set the FM SG output frequency to 90MHz.

6 . Adjust the core of L8 (OSC coil) to obtain maximum deflection of the signalmeter.

q, . RepeatstepsS - 6above .

8.Set the FM SG output levelto 20 - 30d8, and adjustTCz (ANT trimmer) and TC3 (RF trim- mer) at L06MHz, and L2 (ANT coil) and VCB

(RF tuning capacitor) at 90MHz in the same manner as described above in steps 3 - ?.

These adjustments will ensure optimum sensi- tivity in the 90MHz - 106MHz range, and minimum difference in sensitivity between the two extreme frequencies.

9.Retune the dial pointer to a position with no

input signal.

10.Adjust the N core of T2 so that the voltage betweenno. 8 and no.9 terminalson the tuner assemblyis reducedto DC 0V.

11.Set the FM SG output level to 60dB and out- put frequency to 9BMHz, and fine tune the SX-3800to this position.

12.Then rotate the D core of "t2 to obtain mini- mum distortion in the demodulated output (REC terminal)to minimum.

13.Repeat steps g - 12 aboveuntil both require- ments are satisfied.

1.4.Resetthe step 11"again.

15.Adjust the VR2 so that the 5-point SIGNAL indicatorreads5.

16.Set the FM SG output level to 20d8, and turn the FM MUTING switch to ON.

L7. Adjust the VR1 to the point wherethe mutins is operated.

Multiplex Decoder

IConnectthe MPX SG (FM multiplex generator) to the extemal modulator terminalsof FNI SG, therebyusingFM SG asextemal modulation.

1.Set the FM SG output frequency to gBIVIHz, output level to 60dB (unmodulated),and tune the SX-3800to this frequency.

2.Adjust the VRb to obtain a 76kWz signai at no.7 terminalon the tuner assembly.

3.Set the MPX SG modulation output to pilot signal (19kHz) only, and set the FM deviation of ?.5kHz(107cmodulation).

4.Adjust the VR4 to obtain minimum leakageof the 19kHz pilot signalat the REC terminal.

5.Raisethe FM SG output levelto 80d8, and set the MPX SG to Main lkHz (L+R), 6?.5kHz deviation (907o modulation), and pilot signal to 7.5kHz deviation(107omodulation).

6.Adjust the T1 core to within tg0" to obtain minimum distortion in the dernodulated out- put (REC terminal).

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SX-3800 specifications

The Pioneer SX-3800 is a classic stereo receiver that emerged in the late 1970s, embodying the high-fidelity audio aspirations of its time. As part of Pioneer’s widely respected SX series, the SX-3800 is hailed for its exceptional sound quality, robust construction, and an array of features that cater to both audiophiles and casual listeners alike.

One of the SX-3800's standout characteristics is its power output. It delivers a solid 80 watts per channel into 8 ohms, making it capable of driving a variety of speaker systems with ease. This ensures a dynamic audio experience, with clear highs, rich midrange, and deep bass. The receiver also exhibits low total harmonic distortion (THD) ratings, which means the sound produced is clean and faithful to the original recording.

The SX-3800 is equipped with a high-quality AM/FM tuner, which is known for its excellent sensitivity and selectivity. Featuring a large analog dial, it allows users to effortlessly dial into their favorite stations while the signal strength meter helps in fine-tuning the reception. This tuner is complemented by Pioneer’s proprietary Auto-Seek tuning function, making it easier for users to find and lock onto stations.

In terms of connectivity, the SX-3800 comes with several inputs and outputs, including phono, tape, aux, and multiple speaker outputs, offering flexibility for various audio setups. Additionally, the built-in phono preamp ensures that vinyl lovers can connect their turntables with ease, preserving the rich detail and warmth that analog sources are known for.

Another technological highlight of the SX-3800 is its inclusion of a loudness control feature, which allows users to enhance the low and high frequencies at lower volume levels. This feature is particularly useful for late-night listening or in quieter environments where detail is essential but loudness is not an option.

With its solid construction, vintage aesthetics, and a beautiful wood finish, the Pioneer SX-3800 not only performs well but also adds a classic touch to any audio setup. Its blend of features, performance, and timeless design continues to make it a desirable component in the world of vintage audio equipment. Collectors and enthusiasts appreciate the SX-3800 not just for its sound quality but also for its enduring legacy in the rich history of audio technology.