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JBL EON15 Introduction And General Information

JBL EON15 Introduction And General Information

Portable performance systems
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Introduction and General Information
This manual has been prepared to assist technicians with the repair and maintenance of
the JBL EON line of portable performance systems. The procedures described in this man-
ual require advanced technical experience and equipment to perform.
There are no user-serviceable parts inside these products. Opening these
products or attempting to service may expose the user to electrical shock.
Refer servicing to qualified personnel.
Substitutions
Although many of the electronic components used in these products may be available from
electronic suppliers, some components are JBL replacements only. A product repaired with-
out JBL specified components may not meet the factory specifications. The product war-
ranty may be voided by a repair using unapproved JBL components.
Test Equipment
1) Audio Precision System One, or
Distortion Analyzer
Function Generator
2) 20MHz Oscilloscope
3) Desoldering Equipment
4) Digital Multimeter
5) High Power Load Bank
6) Variac
The complexity of the product under repair requires professional audio service equipment.
Do not attempt to repair this product without this equipment.
Factory Repair
In the U.S. and Canada: In the event that an EON product must be returned to the factory
for service, contact JBL Professional Service at (818) 895-3479 for return instructions. Do
not return any merchandise without prior authorization.
Outside the U.S.: Contact the JBL Professional Distributor in your area for service
information.
WARNING
11

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Summary of Contents for JBL EON15

  • Page 1 Introduction and General Information This manual has been prepared to assist technicians with the repair and maintenance of the JBL EON line of portable performance systems. The procedures described in this man- ual require advanced technical experience and equipment to perform.
  • Page 2: Repair Kits

    An audio function generator is also required for testing purposes. The entire recone process uses 3M 1300L adhesive. A tube is included with the recone kit. Additional adhesive may be ordered from JBL, either by the tube (P/N 71715), or by the quart (P/N 63376).
  • Page 3 Recone Procedure Remove grille and inspect speaker carefully before disassembly. Look for and record the following: A) Model Number, Serial Number, Date Code, Customer, and Complaint B) Obvious damage or defects C) Rubbing / Buzzing D) Damaged dust dome E) Damaged cone F) Glue bond, compliance to frame Remove dust dome.
  • Page 4 Inspect and clean the speaker. Return to service. Rediaphragm Instructions 2418H For EON15, EON Power15 and EON15P-1/230 NOTE: YOU MUST REMOVE THE BAFFLE FROM THE CABINET. USE CAUTION TO AVOID DAMAGE TO THE BAFFLE GASKET AS IT CAN BE REUSED.
  • Page 5 #10 TORX driver. Do not discard the cover/screws. Remove the diaphragm assembly from the magnet structure or cover. Identify defect and record Q.A. code per JBL Professional Service Program manual. 10) Check the gap with a .040" gap gauge. Using compressed air and masking or “tuck”...
  • Page 6 B) Power Supply Test Verify that +15V and –15V supplies are at the correct levels. 1) If the LED doesn’t light: Check for shorts from +15V to ground, –15V to ground, and +15V to –15V. Check for opens on +15V and –15V lines. Verify that D204 - D207 are not shorted.
  • Page 7 G) Mic Amp Test Push Mic/Line switch, S201, in. Adjust volume control, P201, fully clockwise. Adjust for 20V P/P at pin 1 of J204. The input level to the board should be 5.6mV (+/– 300uV). Adjust oscillator for 5.6mV and verify that voltage at pin 1 of U202 is equal to 150mV P/P (+/–...
  • Page 8 Excessive power not pulled. Slowly advance input power (Don’t allow +15 supply to go higher than 16V). If power pulled is greater that 20W, before reaching 120VAC in, refer to “Excessive Line Power Test”. As you ramp out the input voltage, verify that +15V supply stays in regulation. If supply is non-existent or excessive refer to “+/–...
  • Page 9 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.
  • Page 10 +/– 77V Supply Test The low frequency power amp might also be pulling excessive current. Check for correct value of R4 and R6 (3.3K) and verify 1.5VDC across them when board is powered. Check for correct value of R5, R9, R21 and R29 (243 ohms) and verify 900mVDC across them when board is powered.
  • Page 11 rounding Q15 emitter to collector. With the collector of Q16 low, D15 will be forward biased and pin 8 of U1 will be at around 3V. If voltage at pin 8 of U1 is lower than the 3V, U1 is defective. Verify: 1.
  • Page 12 4. Crossover distortion in output Refer to Figure A above and note the character of crossover distortion. This is caused by both halves of the output stage (Q1, Q2 on positive side, and Q13, Q12 on the negative side) being turned off right around crossover (crossover from positive drive to negative drive).
  • Page 13 5. Excessive Second harmonic distortion in output Refer to Figure B above and note the character of second harmonic distortion. This is caused by an imbalance in amplifying capability in either the current amplifier or the voltage amplifier. Note that the “Distortion Waveform” could also be inverted in relation to above depending on the polarity of the imbalance.
  • Page 14 A voltage of around .6V is required across the base emitter junction of a transistor to begin to turn it on. Since a total of 4 junctions are in the current amp (Q2, Q1, Q13, and Q12) the bias reference needs to have around 2.4V (4 drops) across it to turn on all four transistors in the current amplifier.
  • Page 15 The voltage at both bases of Q10 and Q11 should be very close to ground potential and the emitters should be at –6V. The voltage drop across R23 and R26 should be around 50mV. Both drops should match within +/– 20%. If all above is not correct check Q10, Q11, R23, and R26.
  • Page 16 J) Low Frequency Filter Test Lift one side of C18. Turn on Generator output A, adjust frequency for 1kHz, and adjust oscillator level to obtain 4V P/P at the input to the filter, pin 1 of J3. Move probe to junction of R63, R64, and C37.
  • Page 17 Measure the response at pin 1 of U4. Note in figure 2 above that the input voltage has not been changed. (Voltage at pin 1 of J3). The other curve represents the response at the output of the second section of the filter. The second section is a moderate Q (Q equals about 2) high-pass filter at 55Hz.
  • Page 18 Measure the response at pin 1 of U3. Note in figure 3 above that the input voltage has not been changed. (Voltage at pin 1 of J3). The other curve represents the response at the output of the third section of the filter. The third section is a low Q (Q equals about .7) high-pass filter at 33Hz.
  • Page 19 Measure the response at pin 1 of U2. Note in figure 4 above that the input voltage has not been changed. (Voltage at pin 1 of J3). The other curve represents the response at the output of the fourth and final section of the filter. The output is fed to the low frequency power amp that essentially has a flat response from 20Hz to 20kHz.
  • Page 20 4. Using a distortion analyzer and an oscilloscope, turn the bias trim pot (VR1) CCW until distortion spikes disappear, and the THD+N reading is below 0.1%. 5. Turn oscillator off, while keeping the amplifier on. 6. Verify the power is between 10 and 20 watts. K) High Frequency Power Amp Test Turn off Generator A.
  • Page 21 L) High Frequency Filter Test Lift one end of C27. Turn on Generator output A, adjust frequency for 1kHz, and adjust oscillator level to obtain 4V P/P at the input to the filter, pin 1 of J3. Move probe to junction R61, C44 and C45.
  • Page 22 Measure the response at pin 7 of U4. Note in Figure 6 above that the input voltage has not been changed. (Voltage at pin 1 of J3). The other curve represents the response at the output of the second section of the filter. The second section is a moderate Q (Q equals about 2) high-pass filter at 1.9kHz.
  • Page 23 High Frequency Response EON Power15 and EON15P-1/230...
  • Page 24 Low Frequency Response EON Power15 and EON15P-1/230...
  • Page 25 Signal Input Assembly Trouble-shooting EON PowerSub A) Initial Setup Connect board under test to a +/– 15V power supply at the designated connector pins. Connect Generator output to XLR input connector. B) Power supply Test Verify that +15V and –15V supplies are at the correct levels. Check for shorts from +15V to ground, –15V to ground, and +15V to –15V.
  • Page 26 1) LED may be defective, and check traces around it. 2) Check reference voltage at pin 8 of U1 = –100mV, and for any short or open circuits around U1. 3) With oscillator off, check that there is 0V DC at pin 1 of U2, if the voltage is greater than 0V, U2 may either be defective or have one of its input pins (2 or 3) disconnected (open trace) from the rest of the circuit.
  • Page 27 4. Check for the presence of +/– 95V at test points 2 and 5 (TP2, TP5). If low or non- existent refer to “+/– 95V Supply Test”. 5. Verify that “Mute Line” voltage at pin 7 of IC U1B is at 15V. Remove power to unit and verify that mute line immediately goes low (–15V).
  • Page 28 verify 750mV DC (+/– 100mV) across them. Check for correct values of R2 and R25 (0.1 ohms, 3W) and verify 5mV (or similar to bias setting) across them when board is powered. If any of the above is not true proceed to “Power Amp Test”. G) Amplifier Muting Test 1.
  • Page 29 This is caused by both halves of the output stage (Q1, Q2 on positive side, and Q8, Q9 on the negative side) being turned off right around crossover (crossover from positive drive to negative drive). This actually takes a small chunk (sometimes only visible in distortion waveform) out of the center of the output waveform.
  • Page 30 Low Frequency Response EON PowerSub...
  • Page 31 Signal Input Assembly Trouble-shooting EON Power10 A) Initial Setup Connect board under test to a +/– 15V power supply at the designated connector pins. Connect Porta-one Generator (or a function generator) output A to XLR input connector. B) “Mic” LED Test Turn Generator A off.
  • Page 32 G) Mic Amp Frequency Response Test Adjust for 20V P/P at 400Hz at pin 1 of J1. Adjust frequency to 20kHz and verify 20V P/P (+/– 1V) at pin 1 of J1. Adjust frequency to 20Hz and verify 14V P/P (+/– 2V) at Pin 1 of J1. H) Signal Indicator Test Set oscillator frequency to 400Hz, Mic/Line switch, SW1 to “Mic”...
  • Page 33 Turn on Generator and adjust frequency to 400Hz. Adjust Oscillator amplitude to obtain 50V P/P at amp output. The waveform should be a nice clean sine wave. The amp will begin to clip at around 57V P/P at the output. If the amp prematurely clips verify that the input to the amp is not clipped.
  • Page 34 tial) check for: incorrect values of D1, D2, R15 or R16; for proper polarity on C10 and C15; for excessive current being pulled (do U3 and U4 run hot?...etc.) and for base emitter shorts on Q1 (2SB1186A) or Q2 (2SD1763A). +/–...
  • Page 35 High Frequency Response EON Power10...
  • Page 36 Low Frequency Response EON Power10...
  • Page 37 Input Assembly Trouble-shooting EON 15PAK A) Initial Setup Connect board under test to a +/– 15V power supply according to the following pin out: pin 3 = +15V, Pin 4 = –15V and pins 2 and 5 = power ground. Connect a function generator output to XLR input connector.
  • Page 38 3) Low Mid Frequency Band: Using the Mic input at mic level (i.e. Switch SW1 in), set the input signal to –60dBu at 400Hz. Verify that the output at pin 1 of J1 is approximately 9.3 dBu.Turn Low Mid Frequency EQ control fully clockwise and verify that pin 1 of J1 is now approximately 21.6 dBu.