Sennheiser HME 26-600 User manual

Subject to alterations
Service manual
HMD/HMDC/HME 26
Broadcast
HMD 26-600SHME 26-600S
HME 26-600
HME 26-600-7
HME 26-100
HME 26-100-7
HME 26-100(4)
HME 26-600(4)
HMD 26-600
HMD 26-600-7
HMD 26-100
HMD 26-100-7
HMD 26-600-X3K1
HMDC 26-600
Headset variants
Cable variants
-6, -H-6
-7, -B-7
-X4F, -H-X4F
-X3K1, -H-X3K1
-X3K1-P48
-X5
Sennheiser electronic GmbH & Co. KG
Am Labor1, 30900 Wedemark, Germany
www.sennheiser.com 1/23
SA 100810
Revision 08/2011
Short description
These headsets have been designed for broadcast use, e.g. for outdoor broadcast and TV
applications.
Features
•Dynamic, closed headphones with supra-aural ear coupling
•Flip-away headphone allows single-sided listening (not for the HME/HMD 26-600S)
•Several microphone variants
•Flexible microphone arm, can be worn on either left or right-hand side
•Single-sided cable routing

HMD/HMDC/HME 26 Broadcast
08/2011 2/23
Safety requirements
Observe safety regulations.
Observe ESD instructions while handling electrostatically endangered components.
Only skilled persons are allowed to alter and repair. For repairs and exchanges only
approved components according to the current spare parts list are allowed.
For safety and certification reasons it is forbidden to alter the product without
authorization. Otherwise, the person who has altered the product is liable for any
consequential damage.
repairs/exchanges The following instructions for overhaul and testing must be followed.
In case of unusual problems please contact your Sennheiser service center support.
CAUTION
During SMD component soldering you may destroy them by using a
standard soldering iron for several seconds.
Only use adapted soldering tools when soldering SMD components.
SMD

Contents
HMD/HMDC/HME 26 Broadcast
08/2011 3/23
1 Product overview............................................................................................4
1.1 Headset................................................................................................................... 4
1.2 Operating control-B-7 (when using the HMDC 26) ....................................... 4
2 Technical data.................................................................................................5
2.1 Technical data HMD 26........................................................................................ 5
2.2 Technical data HMDC 26...................................................................................... 6
2.3 Technical data HME 26 ........................................................................................ 7
3 Exploded view.................................................................................................8
3.1 Exploded view of the complete unit ................................................................. 8
3.2 Exploded view of the headband module ......................................................... 9
3.3 Exploded view of the microphone cap module
(with microphone arm support and cable)9
3.4 Exploded view cable -B-7 (for HMDC 26)....................................................... 10
4 Test and alignment instructions ............................................................... 11
4.1 Measuring and test equipment ....................................................................... 11
5 Disassembly/Assembly .............................................................................. 12
5.1 Disassembly......................................................................................................... 12
5.2 Assembly.............................................................................................................. 14
6 Functional test............................................................................................. 19
6.1 Functional test of the headphones ................................................................. 19
6.2 Functional test of the microphone.................................................................. 19
6.3 Functional test ActiveGard™ (HMD/HME 26) ............................................... 20
6.4 Functional test NoiseGard™ (HMDC 26)......................................................... 20
7 Circuit diagrams........................................................................................... 21
7.1 Cable and connector assignment .................................................................... 21
7.2 PCB of the acoustic units of the HMDC 26 ..................................................... 22
7.3 PCB of the acoustic units of the HMD/HME 26 ............................................. 23

HMD/HMDC/HME 26 Broadcast
08/2011 4/23
1 Product overview
1.1 Headset
쐃Split headband
쐇Padding for the split headband (available as accessory)
쐋Cap microphone side
쐏Microphone arm support of the cap (not visible)
쐄Connecting cable with headset connector
(see “Cable and connector assignment”, page 21)
쐂Microphone arm,
the visualization depends on the the microphone type, see Technical Data
쐆Cap non microphone side/ temple support (HME/HMD 26-600S)
쐊Earpad
쐎ActiveGard switch (HME/HMD 26 only)
쐅Flip-away hinge for flipping away the cap not microphone side
(not HME/HMD 26-600S)
1.2 Operating control-B-7 (when using the HMDC 26)
쐃NoiseGard™ LED
쐇NoiseGard™ ON/OFF switch




















HMD/HMDC/HME 26 Broadcast
08/2011 5/23
2 Technical data
2.1 Technical data HMD 26
2.1.1 Headphones
Transducer principle ___________________dynamic, closed
Ear coupling _________________________supra-aural
Frequency response____________________20 Hz to 18 kHz
Impedance
HMD 26-600 ____________________300 Ωmono/600 Ωstereo
HMD 26-600S ___________________600 Ωmono
HMD 26-100 ____________________50 Ωmono/100 Ωstereo
Characteristic at 1 kHz, 1 V
HMD 26-600/-600S _______________107 dB SPL
HMD 26-100
(ActiveGard is switched off) ________115 dB SPL
Max. SPL at 1 kHz
(ActiveGard is switched on) _____________105 dB SPL
HMD 26-600/-600S at 200 mW _____127 dB SPL
HMD 26-100 at 200 mW
(ActiveGard is switched off) ________128 dB SPL
THD at 1 kHz _________________________< 0.5%
Contact pressure
HMD 26-600/-100 ________________approx. 3.6 N
HMD 26-600S ___________________approx. 4.0 N
2.1.2 Microphone
Type ______________________________BMD 424
Transducer principle of the BMD 424_______dynamic, noise-compensating
Pick-up pattern _______________________hyper-cardioid
Frequency response____________________40 to 16,000 Hz
Output voltage at 1 kHz ________________0.4 mV/Pa
Impedance___________________________300 Ω
2.1.3 General data
Ambient temperature
Operation_______________________–15 °C to 55 °C
Storage ________________________–55 °C to 70 °C
Weight without cable
HMD 26-600/-100 ________________approx. 200 g
HMD 26-600S ___________________approx. 130 g
Cable and connector assignment__________see page 21

HMD/HMDC/HME 26 Broadcast
08/2011 6/23
2.2 Technical data HMDC 26
2.2.1 Headphones
Transducer principle___________________ dynamic, closed
Ear coupling _________________________ supra-aural
Frequency response ___________________ 20 Hz to 18 kHz
Impedance __________________________ 600 Ωmono/1200 Ωstereo
Characteristic
at 1 kHz, 1 mW __________________ 108 dB SPL
at 1 kHz, 1 V ____________________ 110 dB SPL
Max. SPL at 1 kHz ____________________ 120 dB SPL
Active noise compensation
at 100 Hz to 300 Hz ______________ ≥ 18 dB
Attenuation (active and passive) _________ 15 dB to 30 dB
THD at 1 kHz ________________________ < 0.5%
Contact pressure _____________________ approx. 3.6 N
2.2.2 Mikrophone
Type ______________________________ BMD 424
Transducer principle BMD 424 ___________ dynamic, noise-compensating
Pick-up pattern ______________________ hyper-cardioid
Frequency response ___________________ 40 to 16,000 Hz
Output voltage at 1 kHz________________ 0.4 mV/Pa
Impedance __________________________ 300 Ω
2.2.3 General data
Ambient temperature
Operaration ____________________ –15 °C to 55 °C
Storage _______________________ –55 °C to 70 °C
Weight without cable__________________ approx. 210 g
Power supply NoiseGard
Batteries_______________________ 2 x 1,5 V alkaline (type LR 6 = AA)
Rechargeable batteries____________ 2 x 1.2 V (type LR 6 = AA)
Operating time NoiseGard ______________ approx. 60 hours
Cable and connector assignment _________ see page 21

HMD/HMDC/HME 26 Broadcast
08/2011 7/23
2.3 Technical data HME 26
2.3.1 Headphones
Transducer principle ___________________dynamic, closed
Ear coupling _________________________supra-aural
Frequency response____________________20 Hz to 18 kHz
Impedance
HME 26-600/-600(4) _____________300 Ωmono/600 Ωstereo
HME 26-100/-100(4) _____________50 Ωmono/100 Ωstereo
HME 26-600S____________________600 Ωmono
Characteristic at 1 kHz, 1 V
HME 26-600/-600S/-600(4) ________107 dB SPL
HME 26-100/-100(4) _____________
(ActiveGard is switched off) ________115 dB SPL
Max. SPL at 1 kHz
(ActiveGard is switched on) _____________105 dB SPL
HME 26-600/-600S/-600(4)
at 200 mW______________________127 dB SPL
HME 26-100/-100(4) at 200 mW
(ActiveGard is switched off) ________128 dB SPL
THD at 1 kHz _________________________< 0.5%
Contact pressure
HME 26 ________________________approx. 3.6 N
HME 26-600S____________________approx. 4.0 N
2.3.2 Microphone
Type
HME 26-600/-600S/-100 __________BKE 4-2
HME 26-600(4)/-100(4) ___________BKE 4-4
Transducer principle ___________________pre-polarized
Pick-up pattern
BKE 4-2 ________________________omni-directional
BKE 4-4 ________________________cardioid
Frequency response____________________40 to 20.000 Hz
Output voltage _______________________4 mV/Pa ± 2.5 dB
Terminating impedance_________________min. 4.7 kΩ
Supply voltage _______________________5 to 15 VDC
2.3.3 General data
Ambient temperature
Operation ______________________–15 °C to 55 °C
Storage ________________________–55 °C to 70 °C
Weight without cable
HME 26 ________________________approx. 200 g
HME 26-600S____________________approx. 130 g
Cable and connector assignment__________see page 21

HMD/HMDC/HME 26 Broadcast
08/2011 8/23
3 Exploded view
3.1 Exploded view of the complete unit
See also:
See “Product overview”, page 4.
* The PCB is shown as example.
010
060*
070
090
090
020
100
040
030
050*
Non microphone side
HMD/HMDC
HME
Single-sided version
080
Item Designation
010 Headband (headband paddings are not displayed), see page 9
020 Label
030 Clip, non microphone side
040 Cap, non microphone side (not HME/HMD 26-600S)
050 Acoustic unit, non microphone side (not HME/HMD 26-600S)
060 Acoustic unit, microphone side
070 Cap with microphone arm support and cable, see page 9
080 Microphone arm Broadcast
090 Screw 1,8x12
100 Earpads

HMD/HMDC/HME 26 Broadcast
08/2011 9/23
3.2 Exploded view of the headband module
3.3 Exploded view of the microphone cap module
(with microphone arm support and cable)
020
010
030 Note:
Snap the latch with the flange
into the notch of the end piece
for cable routing
Item Designation
010 End pieces of headband right
and left for HMS 26/46
and 2 latches
020 2 yokes for HMS 26 and
2 latches for left and right side
030 Latch for headband
040 Padding HMS 26/46
(not displayed)
010
Item Designation
010 Screw 2x6

HMD/HMDC/HME 26 Broadcast
08/2011 10/23
3.4 Exploded view cable -B-7 (for HMDC 26)
030
010 050
070
100 090
060
020
110
080
040*
060
060
060
insulating
foil
insulating
foil
110
* Platine ist beispielhaft dargestellt
PCB is shown as example
Item Designation
010 Cover
020 Battery housing
030 Knob 10.5x3.7
040 PCB mainboard
050 Optical transmitter
060 Screw 2x8 Torx
070 Cable 1.3 m
080 Cable 1.075 m
090 Insert round 5.2x2.7
100 Insert round 6.3x3.8
110 Insert black

HMD/HMDC/HME 26 Broadcast
08/2011 11/23
4 Test and alignment instructions
4.1 Measuring and test equipment
Note:
Make sure that your measurement and test equipment is regularly calibrated.
Measurement equipment Specification Recommendation
Power supply unit 5 A, 2 x 0 to 30 VDC HAMEG HMP 2020
AF signal generator
(function generator)/
Audio analyzer
ANALOG/DIG
Range from 4 Hz to 100 kHz;
Sinus/Rectangle;
Sweep function;
THD measurement possible;
Filter: A-weighted
Rohde & Schwarz UPP 200 with
digital interface AES EBU 3 or
Audio Precision AP System 2722
Multimeter Measuring range: μADC;
Displayed at least 4 digits
HAMEG 8012
Oscilloscope
Measuring range up to 100 MHz;
2 channels;
Save function;
Time base delayed;
Sampling rate 1.25 GS/s
Tektronix TDS 3012B
Audio amplifier With high impedance
microphone input (e.g. 47 kΩ)
commercial
Dynamometric key for the
headset assembling –commercial

HMD/HMDC/HME 26 Broadcast
08/2011 12/23
5 Disassembly/Assembly
See also:
See “Exploded view”, page 8.
5.1 Disassembly
5.1.1 Removing the earpads
For reasons of hygiene, the earpads should be replaced from time to time. Grasp the
edge of the earpad and pull sharply.
5.1.2 Removing the cap/defective acoustic unit
Note for headsets up to serial number <00200100:
The acoustic units (050/060) have been redesigned. For acoustical reasons always
replace both acoustic units and both earpads (100).
Note for headsets from serial number 00200100:
Replace the defective acoustic unit only (050 or 060). For hygienical reasons the
earpad replacement (100) is recommended.
1. Remove both screws (090) of the acoustic unit (050/060).
2. Carefully put the tip of a small flat-headed screwdriver into the first slot of the
cap (040/070) .
3. Use the screwdriver to lever the cap (040, 070) to the outer side to unhook the
inner nose.
4. Keep the cap (040, 070) and the acoustic unit (050, 060) under some tension
to prevent a movement of the hook to its old position.
5. Do steps 2 thru 4 again for the second slot .
6. Carefully put the tip of a small flat-headed screwdriver at position on the left
and right side near the headband (010).
7. Remove the cap (040/070) from the acoustic unit (050/060) carefully. When
you remove the cap at the microphone side (070), you must make sure that the
leads which are attached to the PCB do not break off.
8. Desolder the microphone arm and the headband leads from the PCB.
5.1.3 Disassembling the microphone arm
See also:
See service information SI 100702-15.



Schraube
Screw

Schraube
Screw

HMD/HMDC/HME 26 Broadcast
08/2011 13/23
5.1.4 Disassembling the operating control (for cable -B-7)
1. Remove the 4 Torx screws (060).
2. Remove the cover (010)
3. Take out the knob (030) and the optical waveguide (050), if needed.
4. Take out the inserts (090, 100, 110).
5. Take out the PCB mainboard (040)
6. Desolder the cable (070, 080) from the PCB mainboard (040), if needed.
5.1.5 Disassembly of the split headband
Removal of the latch for headband
1. Use a small flat screwdriver and press out the latch for headband (030).
After the removal the latch can be damaged or get lost. Recommendation: Do not
install this removed latch again. Use new headband latches.
Removal of the the yoke
Before you remove the yoke (020), disassemble the cap, see section 5.1.2.
1. Take out the headband cable from the headband channel of the yoke (020)
2. Remove the yoke from the end piece of headband (010).
Removal of the end piece of headband.
1. Do steps described in the last both sections (latch+yoke removement).
2. Unscrew the 2 screws of the end piece holder.
3. Remove the cover of the end piece holder. For the assembly of the end piece
keep in mind the laying of the cable.
4. Remove the end piece of headband (010) from the end piece holder. During this
step the headband cable in the cable channel of the end piece comes out
automatically.
Check the headband cable for damages. If the headband cable is damaged, remove
the complete headband.
e.g. 3/64"
Headband cable
Yoke
End piece with notch
for cable routing
Cable channel
of the yoke
Screw
Cover of the
end piece holder
Cable channel
of the end piece
End piece
microphone side
End piece
not microphone side
Stopper
oval
Stopper
round
Latch

HMD/HMDC/HME 26 Broadcast
08/2011 14/23
5.2 Assembly
5.2.1 Assembling the acoustic units and the caps
Note for Headsets up to serial number <00200100:
The acoustic units (050/060) have been redesigned. For acoustical reasons always
replace both acoustic units and both earpads (100).
Note for headsets from serial number 00200100:
Replace the defective acoustic unit only (050/060). For hygienical reasons the
earpad replacement (100) is recommended.
Note for the microphone side cap replacement
The cap on the microphone side (070) and the microphone arm (080) have
mechanically been redesigned. Depending on the serial number of your headset,
you either need the matching older spare parts or the new redesigned ones,
see also SI 100702-15.
1. Attach the acoustic units (050/060) to the headband (010).
2. Solder the leads of the headband cable to the PCB on left and right side.
Solder the microphone cable to the PCB at microphone side
3. Press the caps (040/070) to the acoustic units (050/60).
4. Mount the screws (090) with a torque of 20 Ncm ±3 Ncm.
5.2.2 Attaching the earpads
For reasons of hygiene, both earpads should be replaced from time to time. Attach
the new earpad to the earcup by pressing firmly around the earpad until you hear
all 12 latches lock into place.
5.2.3 Assembling the microphone arm
See also:
See service information SI 100702-15 and also SI 100202-01.
5.2.4 Assembling the operating control (for cable -B-7)
1. Solder the cables (070, 080) at the solder points of the PCB mainboard (040).
2. Attach the knob (030) to the correct position of the PCB mainboard (040).
3. Press the optical waveguide (050) into the cover (010), if necessary.
4. Attach the PCB mainboard (40) with the cable (070, 080)
to the correct position of the cover (010).
5. Attach the battery housing (020) and the cover (010).
6. Press the inserts (090, 100, 110) into the battery housing (020), if necessary.
7. Fasten the 4 screws (060) with a torque of 15 Ncm 1 Ncm.
12 x

HMD/HMDC/HME 26 Broadcast
08/2011 15/23
5.2.5 Assembly of the split headband
Note:
Check the headband cable for damages. If the headband cable is damaged, remove
the complete headband.
5.2.6 Assembly of the end piece of the headband
Note:
The left and the right end piece (010) are different parts:
- Use the end piece with the oval stopper for the not microphone side only.
- Use the end piece with the round stopper for the microphone side only.
End piece
microphone side
End piece
not microphone side
Stopper
oval
Stopper
round
End piece holder

HMD/HMDC/HME 26 Broadcast
08/2011 16/23
1. Put the end piece of the headband (010) into the end piece holder (see figure
below).
2. Completely move down the end piece of the headband (010) to the round/oval
end piece stopper.
Caution:
Do not install the headband cable with a sharpen screwdriver. You can damage the
headband cable. Use only rounded/stub tools.
3. For the microphone side press the headband cable completely into the
headband channel of the end
piece (010). Install the headband cable as shown below.
For the not microphone side first turn the end piece holder to the left side. Then
press the headband cable completely into the headband channel of the end
piece (010). Install the headband cable as shown below and recognize that the
cable routing is on the left side/cable channel side.
4. Snap in the cover.
5. Carefully pull the end of the headband cable to prevent wavy cable routings.
6. Fasten the 2 screws.
7. Check the correct movement of the end piece (010): Move the end piece of the
headband up and down. Ensure that the headband cable is completely inserted
in the cable channel.
Cable channel
of the end piece
Screw
Microphone side
Cable
End piece
holder
Not microphone side
Headband
Cable
End piece
Cable channel
Cable
channel

HMD/HMDC/HME 26 Broadcast
08/2011 17/23
5.2.7 Assembly of the yoke
1. Completely move down the end piece of the headband (010) to the round/oval
end piece stopper.
Caution:
Do not install the headband cable with a sharpen screwdriver. You can damage the
headband cable. Use only rounded/stub tools.
1. Press the headband cable completely into the headband channel of the end
piece (010).
2. Put the yoke (020) to the end piece of the headband (010).
3. Press the headband cable into the left part of the headband channel of the
yoke (020).
Yoke
Cable channel
of the yoke
Cable channel
of the end piece
Headband cable
End piece stopper

HMD/HMDC/HME 26 Broadcast
08/2011 18/23
5.2.8 Assembly of the latch for headband
Note:
After the removal the latch can be damaged or get lost. Recommendation: Do not
install this removed latch again. Use new headband latches.
1. Press the latch for headband (030) completely into the notch of the headband.
Note:
Ensure the correct direction/postion of the notch. The side with the notch shows to
the cable channel side of the end piece of the headband (010).
2. Move the end piece of the headband (010) up and down. Ensure that the cable
is completely inserted in the end piece of the headband (010).
Latch
End piece with notch
for cable routing

HMD/HMDC/HME 26 Broadcast
08/2011 19/23
6 Functional test
See also:
- See “Cable and connector assignment”, page 21.
- See “PCB of the acoustic units of the HMDC 26”, page 22.
- See “PCB of the acoustic units of the HMD/HME 26”, page 23.
6.1 Functional test of the headphones
6.2 Functional test of the microphone
STEP RESULT
Via AF generator supply 1 kHz/100 mV eff ± 5 mV
to the related pins of the cable´s connector.
See “Cable and connector assignment”, page 21.
Put on the headset You can hear the clear 1 kHz signal without any distortions
at the left and right capsule.
STEP RESULT
When testing with pre-polarized microphone of the HME 26:
Suppy the additional P48 voltage (48 VDC).
Connect the headphone connector of the headset´s connecting
cable to an output of the audio amplifier.
Connect the microphone connector of the headset´s connecting
cable to an input of the audio amplifier.
Connect the oscilloscope´s test cable to an high impedance output
of the audio amplifier.
Put on the headset, adjust the microphone to the correct position
and speak into the microphone
You can hear your speech without any distortion at the left and
right capsule.
The amplified audio signal of your voice will be displayed at the
oscilloscope. This visualization is helpfully for the functional test
of the microphone, e.g. trouble shooting.
Oscilloscope
Multimeter
2.54 cm
(1" )
Power supply
8 to 16 V DC Microphone +
Microphone -
25 µF
220Ω
470Ω
Signal
HEADPHONE
Signal
MIC
Audio amplifier
OUT IN
Headphone +
Headphone -

HMD/HMDC/HME 26 Broadcast
08/2011 20/23
6.3 Functional test ActiveGard™ (HMD/HME 26)
6.4 Functional test NoiseGard™ (HMDC 26)
STEP RESULT
Set the “ActiveGard“ switch to “OFF“, if needed.
Supply the AF signal (1 kHz/2 Veff) via AF generator
(1 kHz/2 Veff) to the related pins of the cable´s connector:
Audio Hi/Audio Lo left and Audio Hi/Audio Lo right.
Adjust the AF generator: The 2 Veff amplitude is available at the
headset´s input connectors.
Measure the electrical output signal at the microphone side:
Transducer +/- (signal at the left channel) and
Loudspeaker +/- (signal at the right channel)
See table below
See “PCB of the acoustic units of the HMDC 26”, page 22.
See “PCB of the acoustic units of the HMD/HME 26”, page 23.
1 kHz test signal
at the headphone
input
Measure the level at the transducer +/-
ActiveGard switch = OFF
Measure the level at the transducer +/-
ActiveGard switch = ON
2 Veff 1.85 Veff ±100 mV 420 mVeff ±130 mV
STEP RESULT
Insert 2 completely charged alkaline batteries
(type LR 6 = AA, 1.5 V) or 2 rechargeable batteries.
Put on the headset and switch on NoiseGard via operating control. Ambient noises/low frequencies are hearable downsized/
decreased.