JBL EON15, Введение и общая информация

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E) Excessive Line Power Test
Verify correct polarity and the following parts are not shorted:
C1, C2 (main filters) and D1 D8 (low frequency power amp), D2-D5, C3, C5, C7, C10 (+/–
77V doublers). No section of BR1 (main bridge) should be shorted. Verify that the +15V
and –15V supplies are not shorted. Return to “Main Test Loop” when fault fixed.
Measure across Q1 and Q13 emitters using DC Voltmeter. Slowly ramp up input voltage
never allowing more than 40W to be pulled from Variac. The voltage across the emitters
should be less than 5mV. If excessive refer to “Low Power Amp Test”.
Measure at +HF test point using DC Voltmeter. Slowly ramp up input voltage never allow-
ing more than 40W to be pulled from Variac. The voltage at the output pin, pin 3 of U1,
should be less than +/– 50mV. Monitor the temperature of U1, with your finger. The tem-
perature should warm slightly but not excessively. The Temperature should not rise more
than 10 degrees C after a few minutes of “idle” operation. If any of the above not true refer
to “High Frequency Power Amp Test”.
F) Supply Test
+/– 15V Supply Test
Slowly ramp up Variac, never allowing the supplies to /– 16V. M15V
and –15V supplies. Both should be the correct value +/– .5V.
If a supply is very close to ground potential (Less than +/– 100mV check for:
1.
shorts on the +/–15V supplies; references Z3 or Z4;
2. open or incorrect reference bias sources R52 and R65;
3. open series pass devices Q18 and Q19;
4. +/– 39V supplies absent, proceed to “+/– 39V Supply Test”.
If supply is out of specification (deviation of more than .5V but not close to ground poten-
tial) check for:
1.
incorrect values of Z3, Z4, R52 or R65
2. proper polarity on C32 and C40
3. excessive current being pulled (Do U2-U4 run hot?...etc.)
4. verify that Q18 or Q19 are noted shorted from base to emitter
If supply is high verify that:
1.
Z3 and Z4 are of correct value and are not open
2. R52 and R65 are the correct value
3. Q18 is a 2SD1763A and that Q19 is a 2SB1186A
4. Q18 and Q19 are not shorted Base to Collector, or collector to emitter
+/– 39V Supply Test
Look for open traces between main bridge, BR1, and main filter Capacitors, C1, C2. Look
for open traces between BR1 and power input connector, J1. Verify that BR1 is not open.
Return to “Main Test Loop” after fault found.