JVC PC-X250 - Adjustment Method

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ustment method
Measurement instruments required for Tuner section
adjustment
1
Low frequency oscillator Voltage applied to tuner ---------- +B:DC 4.9V
This oscillator should have a capacity to output VT:DC 12V
0dBs to 600 at an oscillation frequency of Reference measurement ----- 26.1mV(0.28V)/3
50Hz-20KHz output
Input positions ----- AM : Standard loop antenna
2
Electronic voltmeter FM : TP1 (hot) and TP2 (GND)
3
Distortion meter
4
Frequency counter Standard measurement position of volume
5
Wow & flutter meter
6
Test tape Bass ----------------------------------------------------- Off
TCC-112 : Tape speed and running unevenness (3KHz) Active hoper bass pro ------------------------ Off
TCC-140 : Reference level (1KHz) Up and down adjustment of volume ----- Vol : 23
TCC-182A : Head angle (8KHz) , playback frequency
characteristics (1KHz) and dubbing frequency Precautions for measurement
characteristics (125Hz and 8KHz) 1 Apply 30PF and 33 Kohm to the IF sweeper output
Because of frequency - mixed tape with 63 , 1 , 10 and side and 0.082UF and 100 Kohm in series to the
14KHz (250nWb/m -24dB) , use this tape together sweeper input side .
with a filter . 2 The IF sweeper output level should be made as
7
Black tape low as possible within the adjustable range .
TYPE I : AC - 225 3 Since the IF sweeper is a fixed device , there is no
TYPE II : AC - 514 need to adjust this sweeper .
8 Torque gauge : For play and back tension 4 Since a ceramic oscillator is used , there is no need
FWD(TW2111A) , REV(TW2121a) and FF/REW(TW2231A) to perform any MIX adjustment .
5 Since a fixed coil is used , there is no need to
Measurement conditions adjust the FM tracking .
6 The input and output earth systems are separated .
Power supply voltage ---------------- AC 120V (60Hz) In case of simultaneously measuring the voltage in
Reference output -------------- Speaker : 0.866V/3 both of the input and output systems with an
Headphone : 0.245V/32 electronic voltmeter for two channels , therefore , the
Reference frequency and ----- 1KHz , AUX : 450~500mV earth should be connected particularly carefully .
input level 7 In the case of BTL connection amp. , the minus
Input for confirming recording and ------- AUX : -28dBs terminal of speaker is not for earthing . Therefore , be
playback characteristics sure not to connect any other earth terminal to this
Measurement output terminal ---------- Speaker J3002 terminal . This system is of an BTL system .
* Load resistance --------------------------- 3 8 For connecting a dummy resistor when measuring
the output , use the wire with a greater code size .
Radio Input signal 9 Whenever any mixed tape is used , use the band
pass filter (DV-12V)
AM frequency -------------------------------- 400Hz
AM modulation ---------------------------------- 30%
FM frequency --------------------------------- 1 KHz
FM frequency deviation ------------------------ 22.5KHz
PC-X250
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