HHB FlashMic DRM85 User manual

Service Manual
Version 0.91 February 2007

DRM85 FlashMic Service Manual Version 0.91 Page 2 of 22
Table of contents
Table of contents ..............................................................................................2
Overview and layout...........................................................................................3
Disassembly.....................................................................................................4
1. Capsule removal ........................................................................................4
2. Key pad removal ........................................................................................5
3. End Cap removal........................................................................................6
4. AF PCB removal.........................................................................................7
5. Connector PCB removal..............................................................................9
6. CPU PCB removal ....................................................................................10
7. LCD removal ...........................................................................................11
8. LCD lens removal.....................................................................................12
Assembly.......................................................................................................13
1. Capsule replacement ...........................................................................13
2. Key pad replacement................................................................................13
3. End Cap replacement................................................................................14
4. AF PCB replacement ................................................................................14
5. Connector PCB replacement......................................................................14
6. CPU PCB replacement..............................................................................15
7. LCD replacement.....................................................................................15
8. LCD lens replacement...............................................................................15
Firmware including updates ..............................................................................16
1. Firmware problems ..................................................................................16
Known Faults..................................................................................................17
1. Failure of Keyboard buttons .......................................................................17
The FlashMic Family ........................................................................................17
1 DRM85 – Omnidirectional...........................................................................17
2 DRM85C - Cardioid ..................................................................................17
3 Differences between the two models............................................................18
Exploded view .................................................................................................19
Parts list .......................................................................................................20
Parts list – part 2 ...........................................................................................21
Parts list – part 3 ...........................................................................................22

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Overview and layout
This service manual is written for the use of trained service personnel only, severe
damage could be caused by disassembly of the FlashMic by untrained operatives.
The manual is laid out with sections on disassembly, assembly, firmware updates,
known faults, and differences between different models.
The sections at the end show an exploded view of the unit and a full parts list.
Throughout the text the item numbers as shown in the exploded diagrams are
enclosed in square brackets, for example [001]
Please note that only a few component parts are available for the PCB’s as changing
other PCB components is not considered practical for field service, if faults occur the
whole PCB must be replaced.
Tools
Normal workshop tools for work on small electronic assemblies are required; the only
additional items that are essential are a number T06 and T08 Torx driver, do not
attempt to use other tools to remove the Torx headed screws as damage will result.
Notes
Before disassembly takes place, the batteries must be removed.
No part of this manual may be reproduced or copied
© HHB Communications Ltd
FlashMic website www.flashmic.info

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Disassembly
1. Capsule removal
To remove the capsule the protective basket [004] must be unscrewed from the top of
the barrel. This unscrews anticlockwise, when viewed from the top of the microphone.
Ensure that the coloured ring [003] is not misplaced when the basket is removed. Be
careful not to damage or touch the front elements of the capsule.
Next the barrel of the microphone [002] must be unscrewed from the end cap; this is
also removed by unscrewing anticlockwise, when viewed from the capsule end.

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Pull the barrel forward away from the end cap, this will expose the battery
compartment lid [005] and allow access to the screw [013], which holds the capsule
in place.
Remove screw [013] then push the barrel back toward the end cap and the capsule
can be gently pulled from the chassis [006]
2. Key pad removal
The key pad [021] Record, Play and Menu buttons should be removed by using a stiff
but not scratchy narrow tool inserted just above the Record button (shown by arrow), a
narrow nylon cable tie is ideal for this task. If a screwdriver is used it is very easy to
scratch the case of the unit or mark the rubber of the keypad.

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The rubber keypad is lifted away and then the Keyboard PCB [010] can be carefully
removed – Please note that on the lower left hand rear edge (shown by arrow in
diagram below) is the connector that connects to the main CPU PCB and the keyboard
must be removed with the connector square so as to avoid any damage occurring.
3. End Cap removal
The keypad MUST be removed (see 2 above) before the end cap is removed otherwise
damage to the Keyboard and CPU PCB’s WILL occur.
After step 2 above unscrew the barrel [002] and slide away from the end cap. Using a
T08 Torx driver undo the three retaining screws [016]
Then the End cap can be gently removed from the chassis and barrel, take care to
ensure the PCB’s slide out of the end cap squarely.

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4. AF PCB removal
The AF PCB [007] is located inside the chassis [006] and is largely hidden from view
as it is behind the battery compartment; with the end cap removed the end of the AF
PCB (shown by arrow below) can be seen
The capsule, keypad and end cap must all be removed before the AF PCB can be
removed.
The ribbon cable [015] has to be disconnected from the AF PCB, this is done by lifting
the black locking latch on the connector (shown arrowed above), and then the cable
[015] can be carefully pulled out from the connector. Once the cable is free the screw

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[012] T06 Torx is unscrewed. Once the screw is removed the AF PCB can be slid
down and out of the front end of the barrel.

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5. Connector PCB removal
After completion of steps 1-4 above the connector PCB [009] can be removed. Undo
screw [020] with a T06 Torx driver being careful to retain washer [018].
This will leave the connector board only linked via the ribbon cable [014]. Turn the
connector board over to gain access to the ribbon cable latch.

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This latch at either end – shown by arrow above (CPU or Connector PCB) can be
released and the ribbon cable removed, this will then free the Connector PCB.
6. CPU PCB removal
To remove the CPU PCB [008] one Torx screw [019] must be removed and the three
connections from the battery compartment have to be very carefully unsoldered.
Once the screw [019] is removed the connections can be unsoldered (3 connections
as shown by the arrows below) and the CPU PCB removed, this must be done with
care to ensure no damage occurs to the PCB or the battery connecting wires.

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7. LCD removal
To remove the LCD from the Connector PCB, first follow steps 1-5 above and then on
the Connector PCB [009] release the black latch holding the ribbon cable from the
Connector PCB to the LCD module.

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Then unclip the LCD from the PCB by moving the 4 LCD clips (shown arrowed below) to
release the module.
8. LCD lens removal
The LCD lens [022] can be removed from the exterior of the FlashMic with no other
disassembly but it is very difficult to do. It is much easier to remove the lens once the
end cap is removed from the unit.

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Then it is a simple matter to remove the lens by releasing the clip of the lens that is
located near the closed end of the cap by using either your finger inserted into the end
cap or a non-scratchy tool inserted through the keypad opening.
Assembly
In general assembly is the reverse of disassembly but there are a number of steps in
the assembly that require particular care and these are detailed below:
1. Capsule replacement
The capsule replacement is straightforward but make sure that the connector pins
(opposite the screw socket) on the capsule are in correct alignment with the socket in
the unit – the alignment is correct when the pins on the capsule align with the LCD
display window. When replacing the basket make sure the coloured ring [003] is
replaced between the basket and the barrel.
2. Key pad replacement
When replacing the keypad it is very important to make sure that the plug on the
Keypad PCB [010] is correctly located in the socket that is mounted on the Connector
PCB [009] this connector is located at the bottom left hand corner of the PCB in the
picture below (indicated by arrow). The PCB is located precisely by the guides in the
end cap moulding but it is essential to push the Keyboard PCB onto the socket
squarely, otherwise damage to the plug or socket could result.

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3. End Cap replacement
Inside the end cap are guides to hold the PCB’s securely in place, and during
reassembly it is essential to make sure the boards are properly located. When the
rear cap is nearly pushed fully home the USB connector, jack socket, and rotary switch
will emerge from the end of the rear cap – check these are correctly aligned, and do
not force the end cap into place. When replacing the three T08 Torx screws [016] do
NOT over tighten as this could strip the threads in the chassis [006]
4. AF PCB replacement
The AF PCB must be slid down chassis [006] from the capsule end. When the PCB
reaches the ribbon cable carefully fold the cable so that it goes under the AF PCB and
the free end protrudes for connection after the T06 Torx screw [012] is inserted.
Reconnect the ribbon cable making sure the latch on the ribbon cable socket is fully
open, then insert the cable fully and close the latch.
5. Connector PCB replacement
Lay the Connector PCB beside the CPU PCB so that the ribbon cable can be inserted,
make sure the latch on the ribbon cable socket is fully open, then insert the cable fully
and close the latch. The Connector PCB can then be folded over on top of the CPU
PCB – check the ribbon cable folds neatly between the two boards. Then screw the
Connector PCB into place using the T06 Torx screw [020] and washer [018]

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6. CPU PCB replacement
Check that the CPU PCB holes for the soldered connections are clean before
reassembly. Insert the CPU PCB in place checking the battery connections are in place
in the PCB holes then screw the board in place using the T06 Torx screw before
soldering the connections.
7. LCD replacement
Note that there are two alignment pins to allow easy positioning of the LCD module,
when re attaching the ribbon cable first make sure the latch is open then ensure that
the cable is fully inserted, before closing the socket latch
8. LCD lens replacement
The LCD easily clips back into place but ensure the inside surface is cleaned before
assembly of the end cap onto the unit.

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Firmware including updates
The FlashMic firmware is held in non-volatile memory and two copies are kept in
memory to ensure that operation is still possible even if the currently in use firmware
somehow becomes corrupt.
1. Firmware problems
Generally, most booting, freezing or locking up problems have been due to the earliest
release of firmware, v3.02.10, which could corrupt the flash memory file system if the
batteries were allowed to run flat in the mic. This bug was removed in an update to
v3.02.12 that was the subject of a technical bulletin back in August 2006; all
microphones should have been updated at that time. The current firmware is
v4.04.06, which contains a still more secure file system.
The firmware for the FlashMic may be updated from time to time and the latest version
will be available for download from the website:
www.flashmic.info
2. File corruption
FlashMic’s with "corrupt" files systems (and, indeed, any FlashMic) should be
reformatted and then updated to v4.04.06. All data will be lost.
There are two operator recovery options (first fit fresh or fully charged batteries):
Try ‘A’ first
A. Hold down the REC and M buttons whilst powering on. The display will show DRM85
and go no further. Move the rocker switch up or down. If the display shows SAME,
them remove the batteries and start again, but move the rocker switch in the opposite
direction to before (i.e., turn switch up if the switch was turned down before). The
display should show UPDATE, with a progress bar. If successful, note, the firmware
version, and then perform a forced format, as described in ‘B’
B. Forced reformat. Hold down REC, PLAY and M buttons whilst powering on. The
display should show DRM85, then the firmware version, then "FMT N" Use the rocker
control to select "FMT Y" and press in to select (all data will obviously be lost).
Assuming you manage to re-update in ‘A’ and successfully reformat, then update the
firmware to v4.04.06. Do the update twice (as stated above the Mic holds two copies
of the firmware; you are choosing between the two copies in ‘A’ above, so it's
important that both copies are updated).

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Known Faults
To date there have been very few re occurring faults, most problems relate to the use
of very early firmware, please see above
There is one known hardware problem that has occurred on a few occasions and that
is detailed below:
1. Failure of Keyboard buttons
This fault is exhibited by a total lack of any operation being possible from the Record,
Play or Menu keys.
This is caused by the socket that is mounted on the Connector PCB [009] becoming
disconnected from the Connector PCB and requires disassembly of the unit as detailed
in disassembly steps 1-5 above.
It will be found that when the Keyboard PCB [010] that the CPU PCB connector is
attached to the plug
PHOTO
The connector can then be re soldered onto the PCB note that there are small
alignment pips on the socket to locate the socket square in the PCB, it is most
important to ensure the socket is square to the PCB once soldering is complete.
PHOTO
The FlashMic Family
There are currently two different models in the FlashMic range and Omni and Cardioid:
1 DRM85 – Omnidirectional
The pick up of audio is broadly the same all around the microphone
2 DRM85C - Cardioid

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The pick up of audio is higher from the front of the microphone than from the sides or
rear.
3 Differences between the two models
The Capsules are two different types as shown below, note that it is easy to distinguish
the cardioid as it has two extensions on either side of the front plate of the capsule.
Cardioid Omnidirectional
Capsule Omnidirectional part number – 512514
Capsule Cardioid part number
And to ensure that the units can be differentiated from the exterior the barrel and cap
are marked differently
Barrel Omnidirectional part number – 514478
Barrel Cardioid part number –
Please note that the barrel and end cap are supplied as a matched pair to ensure the
logo on the barrel is correctly aligned with the with the keypad.
All the electronics and the rest of the unit are identical

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Exploded view

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Parts list
Item No. Part No. Description
001 512514 Microphone module Omnidirectional
002 514478 Barrel & end cap (supplied as matched pair)
003 511565 Coloured ring, purple
004 77535 Basket with pop protection
005 93126 Battery compartment SKM-G2
006 90343 Chassis
007 517630 Printed circuit board AF
008 517631 Printed circuit board CPU
009 517632 Printed circuit board Connector
010 517633 Printed circuit board Keyboard
011 511568 LCD
012 22980 Screw 2.5x4 DIN7985
013 Screw ??
014 87150 Flat cable 30xRM0.5
015 87149 Flat cable 15xRM0.5
016 83055 Countersunk screw MEM2.5x8 TORXT8 DIN7500
017 92092 Label silver - Printed as ordered
018 60108 Washer
019 83054 Screw CEM2x6 TORXT6 DIN7500
020 83051 Screw M2x12 TORXT6 ISO7045
021 512510 Rubber Key pad - REC, PLAY, MENU
022 512508 LCD Lens 34.5x21x2.2