Notes on the Troubleshooting and Repair of Audio Equipment and Other Miscellaneous Stuff


  6.3) Electrical causes for loudspeaker damage

These are not going to be covered by any warranty!  Of course, not mentioned
below are: fire, flood, falling from a tenth story window, getting run over
by a bulldozer, or being plugged into the wall outlet instead of the stereo,
etc. :-).

(Portions from: Lasse Langwadt Christensen (fuz@control.auc.dk)).

1. DC bias across speaker will cause the voice coil to overheat.  Windings may
   short out or open up.  Also see (3), below.  This usually results from an
   amplifier output stage failure - shorted capacitor, for example.

2. High power clipped signal:

   * A clipped signal contains a lot of high frequency energy and that could
     burn a tweeter, because the voice coil overheats.

   * The clipped signal could have a amplitude so large that the voice coil
     hits the magnet and is bent. It's a permanent damage but not always
     terminal, because the might still work, but make a scraping noise.  If
     you play loud with it for a long time (and it doesn't burn out - see (3),
     the part scraping against the magnet might wear off.

3. If the speaker is overheated, because of high power for a long period of
   time, the voice coil could expand and scrape against the magnet, and perhaps
   short some of the turns.  This is not always permanent, and some
   manufacturers use Teflon on the magnet, so that it's less likely to cause

  6.4) Repairing loudspeaker drivers

As noted above, if you are dealing with a high quality system, leave these
repairs to professionals or obtain an entire replacement as some reduction
in audio quality may result from the abuse you are about to inflict on
the poor defenseless driver.

We will address two types of repairs: physical damage to a speaker driver
cone and an open voice coil (actually, wiring outside the voice coil).
However, serious damage to the cone or just plain deterioration of the
suspension components may require replacement of the entire driver unless
a close enough match can be found.

For more information on loudspeaker repair, see: "Speakers (big, small, in
between)" also at this site.

  6.5) Repairing speaker driver cones

Minor damage to the cone can be repaired using a flexible adhesive like
weatherstrip cement and a piece of thick paper to reinforce the seam or
hole if necessary.  Since this will not totally perfect match with the
original paper cone, there could be audible distortion at certain
frequencies particularly at higher volume levels.  However, such a repair
will be better than nothing.  Cut the paper in a shape and size to just
overlap both sides of the torn area or completely cover the puncture.
Use just the smallest amount of adhesive to fasten your 'splint' to the
cone.  The less material you add, the more likely that the audio effects
will be minimal.

(From: M. Przytarski (m.r.p.@ix.netcom.com)).

I have repaired many field-coil speakers, and there is one sure proof
way my grandfather showed me (and several Tube Radio rebuilding mags
suggest the same).

Take a milk glue (Elmers or such), and rub it around the crack.  Then
take a piece of brown lunch bag and rub it with glue.  Place it over
the crack, and rub some glue on it, pressing it in place.  The glue
should by now soak the paper of the cone and bag.  When dried you cant
tell the difference in sound and its as sturdy as ever.  This also
works for those units that a animal (or kid) has put a hole in.  I
repaired a speaker that was missing almost half of the cone from mice.
It sounds great and was cheap to do.

  6.6) Some sources for loudspeaker repair parts and services

(I have not dealt with any of these places personally - these are all based
on recommendations of others.)

* Simply Speakers, 11203 49th St. N., Clearwater, FL 34622,  Voice phone:
  (813) 571-1245, Fax: (813) 571-4041, http://www.simply-speakers.com,
  provides speaker repair services and also sells do-it-yourself refoaming
  kits for repairing foam edge surrounds on most round 4" to 15" and oval
  6" x 9" speakers.

* Stepp Audio Technologies, P.O. Box 1088, Flat Rock, NC 28731, 1-704-697-9001.

* The Circuit Shop, 3716 28th Street, Kentwood, MI 49512, 1-800-593-0869 or

(From: Raymond Carlsen (rrcc@u.washington.edu)).

Various sizes of paper cones and foam-edge replacements are available from
MAT Electronics @ 1-800-628-1118.  They range in price from less than a dollar
to about $5 for the largest (15") drivers.  The downside is there is a $25
minimum.  However, they also sell electronic components like flybacks, video
heads and belts, ICs and transistors, etc.  So coming up with a minimum order
may not be too difficult.

(From: Johnion (johnion@aol.com)).

I was given a pair of infinity speakers and ordered replacement cones from The
Speaker Plac. As long as the problem is just the cones, the kit is great (and

These are the numbers I used around a 1-1/2 years ago:

* The Speaker Place - NEW FOAM, 3047 West Henrietta Road, Rochester, NY 14623,
  Phone: 1-800-NEWFOAM (1-800-639-3626), Fax: 1-800-2FXFOAM (1-800-239-3626),
  Voice Mail: 1-800-FOAMMAIL (1-800-362-6624). Email NEWFOAM@msn.com, Web:

(From: T Schwartz (toschwartz@worldnet.att.net)).

I've had excellent results sending drivers to Millersound Labs:

* Millersound Labs, 1422 Taylor Road, Lansdale, PA 19446, Phone 215-412-7700,
  Fax 215-412-0542

  They can re-foam or re-cone depending on what is needed, they are fast, easy
  to deal with, and IMHO, reasonably priced.  Call them for a quote.

(From: jl (jlager@tir.com)).

* Orange County Speaker, 12141 Mariners Way, Garden Grove, California,

* (From: Aan Jerig (ajerig@gate.net)).

  Lakes Loudspeaker, 4400 W. Hillsboro Blvd., Coconut Creek, FL 33073,

  6.7) Repairing an open driver

An open driver can sometimes be rescued by tracing the input wires through
the cone and under the center protective dome.  The most likely places
for these wires to break are right at the place where they pass through
the cone and just after they pass under the dome.  Note: some drivers have
replaceable voice coil units.  If this is the case, you should probably
just replace the entire unit.

First, scrape away the insulating varnish on the front of the cone where
the wires emerge and head toward the center.  Use your ohmmeter to test
for continuity here.  If you find that you now are measuring a reasonable
resistance - a few ohms, then trace back to determine which of the two
wires is broken or has had the solder connection come loose.  If it is still
infinite, you will have to go under the dome.

Use an Xacto knife to carefully remove the dome.  Use a shallow angle and
cut as near the edge as you can.  Take care not to puncture the paper cone
which may continue under the dome as the voice coil may be of a smaller
diameter than the dome.  The shallow cut will also provide a base to
reattach the dome if you are successful.  Carefully scrape off a bit
of the enamel insulation as near to the voice coil as possible and test
with your ohmmeter once again.  If the resistance is still infinite, there
is nothing more you can do but salvage the magnet for fun experiments or
erasing floppy disks.  There is essentially no way to replace just the
voice coil unless your driver has a removable voice coil unit (in which
case you would not be reading this).

If the resistance now measures normal - a few ohms, trace back to
determine which wire is broken and use some fine (e.g., #30 gauge) wire
to bridge the break.  You will have to scrape off the enamel insulation
to permit the solder to adhere.  Make sure it is secure mechanically first -
a speaker cone is a rather violent environment for soldered connections.
Finally, use some flexible adhesive to protect and reinforce the solder
connections, to glue down your new wire along its entire length, to
protect and reinforce the place where the wire passes through the cone,
and finally, to reattach the central dome.  Let the adhesive dry thoroughly
before playing the finale to the 1812 Overture.

  6.8) Loudspeakers - repair or replace?

Assuming that the cabinet is in reasonable condition, the question arises:
is it worth replacing broken, damaged, or worn out drivers or faulty crossover
components that are not repairable rather than just dumping the speaker

It is very straightforward to swap drivers as long as you get ones with
similar characteristics.  It all depends on what you want out of a loudspeaker.
If you are basically happy with them, then it will be a lot cheaper than
replacing the entire speaker system(s).  However, speaker system quality has
improved considerably in the last 15 years so now may be the time to upgrade.

As far as crossover components are concerned, these are basically common
electronic parts and replacement is probably worthwhile.

However, if one driver has a deteriorated suspension, it is likely that
its mate does as well and that other drivers may not far behind.  Replacing
**all** the internal components of a loudspeaker may not be worth it.

Radio Shack as well as places like MCM Electronics and Dalbani have
a variety of replacement drivers, and crossovers and parts.

  6.9) Speakers wired in series?

(From: Frank Fendley (frank.fendley@datacom.iglou.com)).

Wiring speakers in series increases the impedance of the load, generally 
allowing less expensive output chips and smaller heatsinks, due to reduced
current.  It also decreases the amount of output audio power in most cases,
since power is inversely proportional to impedance for a given voltage.

Many cheaper home stereo receiver and power amps are configured in a similar
manner.  If you have a switch and output connectors for "A" and "B" speakers, 
in some cases when you turn the switch to "A+B", the two left speakers and the
two right speakers are wired in series.   To find out if this is the case on
your stereo, hook up only one set of speakers to the "A" jacks.   Turn the
speaker select switch to "A+B".   If you have no audio through the speakers,
then your receiver or power amp is configured to place the speakers in series 
with both sets of speakers are connected.   On better stereo equipment, if you
have only one set of speakers and select the "A+B" switch setting, your 
speakers will still function, indicating that the speakers are wired in 
parallel in the "both" position.

Bottom line - the answer is money (isn't the answer always money?).   It's 
cheaper for the manufacturers to design for speakers in series.

  6.10) Comments on speaker shielding

When loudspeakers - even those little speakers that came with your PC - are
near TVs or monitors, there may be problems with the fringe fields of the
powerful magnets affecting color purity, convergence, or geometry.  Speakers
designed to be used with PCs in close proximity to their monitor will likely
include some internal shielding.  This may even be effective.  However, the
large powerful loudspeakers used with high performance stereo systems will
likely not have such shielding.  The best solution where display problems have
been traced to the loudspeakers is to move them further away from the TV or
monitor (and then degauss the CRT to remove the residual magnetism.  Where
this is not possible, shielding of the speakers may be possible:

(Also see the document: "TV and Monitor CRT (Picture Tube) Information".)

(From: Lionel Wagner (ck508@freenet.carleton.ca)).

Put a Tin can over the magnet.  This will reduce the external field by
about 50%.  If more shielding is desired, put additional cans over the
first, in layers, like Russian dolls.  (Note: a Tin can is actually made
nearly entirely of steel - the term 'Tin' is historical. --- sam)

(From: Nicholas Bodley (nbodley@tiac.net)).

While both electrostatic and electromagnetic (E/M) fields can affect the paths
of the electron beams in a CRT, only E/M fields are likely to be strong enough
to be a problem.

Magnetic shields have existed for about a century at least. Some decades ago,
a tradenamed alloy called Mu-Metal became famous, but it lost its effectiveness
when bent or otherwise stressed. Restoring it to usefulness required hydrogen
annealing, something rarely done in a home shop (maybe one or two in the USA). 

More-recent alloys are much less fussy; tradenames are Netic and Co-Netic.

Magnetic shields don't block lines of force; they have high permeability,
vastly more than air, and they guide the magnetism around what they are
shielding; they make it bypass the protected items.

I have been around some shielded speakers recently, but never saw any
disassembled. They looked conventional, must have had the "giant thick
washer" (my term) magnet, and seemed to have a larger front polepiece than

They had a shielding can around the magnet; there was a gap between the front
edge of the can and the polepiece. I suspect that a second internal magnet was
placed between the rear of the main magnet and the rear (bottom) of the can,
so there would be minimal flux at the gap between the can and the front
polepiece. Holding pieces of steel close to the gap between the can and the
polepiece showed very little flux there.

Modern magnets are not easy to demagnetize, in general.

(From: Dave Roberts (dave@aasl.demon.co.uk)).

The *good* so-called magnetically screened speakers rely on two means of
controlling stray flux.  The static field from the magnet on the speaker
(which would cause colour purity problems) is minimized by the design of the
magnet.  This is often at the expense of gap field linearity, leading to
greater distortion - not that most users seem to worry about that...

The mains varying field is minimized by use of a toroidal mains transformer,
but the more recent mains powered speakers seem to be coming with *plug top*
PSUs, which take the problem further away.

Chapter 7) Telephone Equipment

  7.1) Telephone basics

* Connections to 'Plain Old Telephone Service (POTS)' is via two wires.
  POTS is the type nearly everyone currently has to their residence.  Newer
  ISDN or fiber lines use different techniques.

* The wires are called 'Tip' and 'Ring'.  This terminology has nothing to do
  with telephone ringing but is historical; Tip and Ring were connected
  to the tip and ring respectively of the plug used on manual switchboards.

* Tip and Ring color codes are as follows - this is not always adhered to!

                              Type A               Type B
      Phone line             Tip,Ring             Tip,Ring
   First line (Pair 1)      Green,Red            White,Blue
   Second line (Pair 2)     Black,Yellow         White,Orange
   Third line (Pair 3)      White,Blue           White,Green

  Type A is often simply called 'quad' and is the most inexpensive cable.
  However, the conductors are usually not twisted and type A should not
  be employed in new installations especially where computer modems or fax
  machines are to be used on any of the lines as crosstalk between
  multiple phone circuits in the same cable may result in excessive
  transmission errors and interference with normal phone conversations.

  For type B, the colors refer to the dominant one if the wires are striped.
  Each pair is twisted together which greatly reduces crosstalk.

* On RJ11 type connectors, Pair 1 is the central two wires, Pair 2 is the
  next two, and Pair 3 are the outer wires if there are 6 conductors - many
  RJ11 cables only have 2 or 4.

* Tip will be approximately +50 VDC with respect to Ring when phones (or
  computer modems or fax machines) are on-hook.  Test with a multimeter.

* Ringing voltage is about 90 VAC.  A neon light bulb (NE2) can be used
  to test for this if a multimeter is not available.

* When off-hook (dialing or talking), there will be a DC voltage of
  approximately 5 to 15 V between Tip and Ring.  This is needed for the
  phone circuit and also is used to power the dialing in phones without
  a separate AC supply or adapter.

* The on-hook and ringing voltages can give you a shock but are probably
  not particularly dangerous to healthy people.  Still, it is best to
  work on phone wiring with it disconnected from the telephone company's
  feed or with another phone on the same circuit off-hook.

* Some phones will work with only one of the two possible polarities of
  Tip and Ring while others incorporate a bridge rectifier (for power)
  and will work either way - test both ways if a phone does not dial
  or work at all.

* DTMF refers to the Dual Tone Multi-Frequency dialing touch tone codes.
  Each number, *, and #, are represented by a pair of audio frequencies.
  (You can hear the individual ones by holding down multiple buttons on
  an old style ATT Touch Tone phone).  See the section: "DTMF codes".

  7.2) DTMF codes

DTMF (Dual Tone Multi-Frequency) are the tones that phones use.  The
frequencies are as follows:

     Hz     1209   1336  1477   1633
    697       1      2      3     A
    770       4      5      6     B
    852       7      8      9     C
    941       *      0      #     D

Follow the rows and columns to the number you want to know the frequencies
of and this  table will show you.  The column of letters at the right is on
some Ham radios.

Where an old style ATT Touch Tone phone's DTMF frequencies need to be adjusted,
accuracy of better than 1 Hz is easily obtained without fancy equipment - just
another working tone dialing phone.  See the section: "Classic ATT Touch Tone phone 'battlewagon' will not dial properly".

For more information on DTMF coding, decoding, equipment, chips, etc., see
the DTMF FAQ at:


  7.3) Phone jack or extension installation or repair

The phone companies would have you believe that installing or repairing
phone wiring is somewhere between rocket science and nuclear physics in
complexity.  In fact:

* Installing new jacks consists of two parts: running the wires and
  hooking them up.  The only difficulty with running the wires is getting
  between floors.  Connecting them is a matter of matching the colors
  of the insulation, stripping, wrapping around screws, and tightening
  the screws.  Even if you are color blind, this is not difficult.

* Unless you disturb it, phone wiring rarely goes bad - even in old
  houses.  Thus, if you have any amount of handyperson ability, paying
  the $2 a month inside wiring insurance is throwing away $24 a year.

* Unlike electrical wiring, phone wiring does not have serious safety
  issues associated with it.  However, you could get a mild shock from
  touching the two wires of an active phone line.  The on-hook voltage is
  about 50 VDC and if someone were to try calling your number at the same
  time, the ringing voltage is around 90 VAC.  Both of these are easily dealt
  with: put a jumper between the two phone wires where they enter your house
  while you are working on the wiring.  This will result in an 'off hook'
  condition and outside callers will get a busy signal.

  7.4) Answering machine comments

Most answering machines still use one or two tape decks.  Most problems
are mechanical.  Refer to the sections on the relevant tape player/recorder
problems.  The newest ones are fully digital electronic - forget repairs
unless obvious bad connections, physical damage, power supply, or phone
line side failure.

* Many non-mechanical problems with answering machines are related to the
  circuitry connected to the phone line.  This is subject to the high on-hook
  and ringing voltage and possible voltage spikes due to lightning, etc.

  Testing of the components on the phone line side of the coupling transformer
  is a worthwhile exercise and may reveal a shorted semiconductor or capacitor.

  See the section: "Checking phones and answering machines for electronic problems".

* If the outgoing message (OGM) or phone messages do not record or playback,
  check for broken wires at the appropriate tape heads and clean the mode
  selector switches.

* With endless loops outgoing message cassettes, the metal strip that is
  used to sense the beginning can wear or become dirty.  Try a new cassette
  or clean it.

* Like VCRs, there may be various 'mode switches' or position sensors.  Where
  these are physical switches, they may have dirty or worn contacts.  Optical
  sensors can fail as well though it is unusual.

* Mechanical problems unique to answering machine tape transports are also
  possible.  Some very clever engineering is often used to share parts
  where two tape transports are used. Parts may have popped off or broken.
  Springs may have sprung or weakened.  Sliding parts may have jammed.  Look
  for loose parts or broken pieces when the unit is disassembled.  Careful
  inspection during operation may reveal whether it is getting stuck due to a
  mechanical failure.

  7.5) Answering machine delays after playing OGM

This may be one of those machines where it has to go through the entire
outgoing message (OGM) tape before allowing recording of the phone
conversation - If it is, then just get yourself the shortest outgoing
message tape you can find and time your OGM to nearly fill it.

Also, if you are trying to use an OGM tape recorded on another answering
machine, even if the tape is compatible, the frequency or coding of the
control tones - the beeps - may not be the same.  Try re-recording it
on the machine in question.

If these are not the problems, the machine may not be sensing the beep code
put on the tape when you record the OGM or the beep is not being recorded
properly.  This is likely an electronic or logic problem requiring the
schematic unless you get lucky with bad connections or a broken wire at
the tape head.

  7.6) Answering machine picks up then hangs up

* If it has a 'telco' and a 'phone' connector verify that you are plugged
  into the 'telco'.  Otherwise, it may hang itself up.  Who knows.
  If someone else attempted a repair, these jacks could even have been
  replaced interchanged.

* Measure voltage on the relay coil.  If it actually disappears when
  the relay cuts out, then something is telling the relay to turn off.
  If it is just reduced, then there may be a power problem.  If it
  is relatively stable, then the relay may be bad.

* Test components near the telephone connection for shorts/opens.
  Parts connected to the telephone line get abused by the ringing
  voltage and other transients.  Maybe you will get lucky and find
  a fried part.

* If you can identify the power supply outputs, verify their voltages
  if possible.  Check the 'wall wart' if it uses one for proper output.

* Make sure that the tape mechanisms have completed their cycles.  While
  unlikely, it is possible that the logic gets confused if one of the
  tape units has not reset itself due to a mechanical fault like a bad belt.

* As usual with cheaply made consumer stuff (as well as cheaply
  made expensive industrial stuff), check for bad connections.

Beyond this, circuit diagrams would be a definite plus.

  7.7) Answering machine does not complete cycle

This is often a mechanical problem.  As it goes through the cycle, see
if the mechanism is perhaps getting hung up at a certain point do to
a weak spring or motor.  A cam may get stuck or a solenoid may fail
to engage.  Gently prodding the uncooperative part (or any likely parts
if the appropriate one is not obvious) may convince it to continue and
allow you to make a diagnosis.

For endless loop outgoing cassettes make sure that the metal sense strip
is not worn off and that the sensor is making good contact.  Try a new
outgoing message cassette or manually short the sensor contacts to see
if it will then shut down.

  7.8) Answering machine has weak outgoing message

You probably have no way of knowing since you probably never listen
to the outgoing message, but did the problem happen suddenly?

Does playback of the outgoing message directly to the speaker appear
to be at normal volume?

Do incoming messaged get recorded at normal volume?

First, confirm that the unit is in good mechanical condition.  See the
section: "General guide to tape deck cleaning and rubber parts replacement".
Clean the tape head and inspect for anything that may be interfering with
good tape-head contact.  Clean the internal record/play selector switches.
Dirty contacts can result in any number of symptoms.

Assuming that none of this helps significantly, you are left with a problem
in the electronics.

If local record and playback of the the outgoing message works normally, the
problem is not a bad tape head.  It is probably in the interface to the phone

If local record and/or playback do not work correctly, then there are likely
problems with that circuitry. 

One other slight possibility is that you have so much equipment (phones,
modems, fax machines, etc.) on the phone line that in your house that the
answering machine is not able to drive the line properly and reduced
outgoing message volume is the result.

  7.9) Newly installed phone will not tone dial

If a Touch Tone phone that was previously working now does not tone dial
from a new jack or new residence (the button presses are totally ignored,
but all other functions are unaffected), the red and green wires are
probably interchanged at the new jack, or the phone itself is miswired
(the wires inside the phone may have been interchanged to compensate for
an incorrectly wired jack at the old location).

Newer electronic phones will utilize either polarity.  The older ATT
battlewagons will only dial when hooked up with the correct polarity.
This does not affect conversation, ring, or rotary phones.

  7.10) Cordless phone problems

There are several types of problems with cordless phones that can be
diagnosed and repaired without sophisticated test equipment.  Anything
involving problems with the RF or digital circuitry is not likely to
be within the scope of your capabilities, at least not without complete
schematics (yeh, right), test equipment, and a miracle or two.

1. Bad rechargeable battery - dead, shorted cell(s), or reduced capacity.
   The NiCd battery packs in cordless phones are usually easily replaced
   for around $5-10.  This really is the best solution.  The problem is
   almost never in the charging circuits.  Replacing individual cells is
   not recommended.  Battery packs can be built up from individual NiCd
   cells with solder tabs for a modest cost savings.  Reuse the old battery 
   pack connector (you may need to do this with a replacement pack as well
   if the new connector is not identical to the old one), double check
   polarity, and tape and insulate your homemade pack after soldering to
   prevent shorts.

   A NiCd battery pack with shorted cells will either prevent operation
   totally or keep the 'battery low' light resulting in a weak, noisy, or
   intermittent connection.  If the voltage measured on the battery pack
   after 24 hours of charging is less than 1.2 V times the number of cells
   in the pack, it is most likely bad.

2. Dirty keypad - resulting in intermittent, incorrect, or no operation
   of buttons on handset.  This may be due to internal migration of some
   unidentified substance (how else to describe disgusting sticky gunk that
   has no right being there on multiple samples of the same model phone) or
   from external spills.  If you are lucky, the keypad can be disassembled
   without resorting to drastic measures.  There may be screws or it may
   snap apart once access is gained to the inside of the handset.  Clean
   contact surfaces on both the rubber button panel (or plastic keys) and
   the circuit board first with soap and water and then with isopropyl
   alcohol.  Dry thoroughly.

   If the keypad is assembled with 'upset' plastic (fancy term for little
   melted plastic posts), then you should probably try contact cleaner sprayed
   as best as possible through any openings before attempting to cut these
   away since reassembling the keypad without the plastic posts will be
   difficult.  However, I have successfully repaired these by breaking off the
   tops of the posts to remove the circuit board and rubber keys, and then
   using a dab of windshield sealer on each post as an adhesive to hold the
   thing together after cleaning.  However, I much prefer screws :-).

3. Bad AC adapter on base station - see the chapter: "AC Adapters."  This
   will likely result in a dead base station.

4. Bad phone line connection - don't ignore this possibility - test with
   another phone.

5. Bad circuitry on phone line side of interface (coupling transformer) -
   inspect for blown or shorted components.

6. Bad connections or broken circuit board - if the handset has seen
   violent service, these are likely possibilities.  See the section
   on: "Equipment dropped or abused".

7. You forgot the code number - some phones use a multidigit code number
   as a marginal security feature which must match on handset and base
   station.  If the battery goes dead in the handset or the AC adapter
   is pulled on the base station, this code may be forgotten.  You do have
   the user's manual, right?

   BTW, do set this code to a non-default value.  I was once able to dial out
   on my neighbor's cordless phone using my phone from my house as a result, I
   suspect, of their phone being set to its default code!

8. Base station and handset out of sync - some models require that the base
   station initialize the handset before any communication is possible
   between them.  Put the handset on the base station for a few seconds to
   reset.  This can happen at any time due to circumstances beyond human
   control but will almost certainly happen if you replace or disconnect the
   battery in the handset of these model phones.

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Written by Samuel M. Goldwasser. | [mailto]. The most recent version is available on the WWW server http://www.repairfaq.org/ [Copyright] [Disclaimer]