Toshiba TV29C90 problem; Image fades to black...

[Mark D. Zacharias]

Smitty Two wrote:

In article <2Lo7i.6745$5j1.1214@newssvr21.news.prodigy.net>,
"Mark D. Zacharias" <spammenot@nonsense.net> wrote:

Smitty Two wrote:
In article <J%f7i.62157$V75.33167@edtnps89>,
"Dave" <dspear99ca@yahoo.delete.com> wrote:



Has technology evolved so that a momentary crossing of speaker
wires could not destroy expensive output transistors?

It hasn't as much to do with technological evolution as it has to do
with intelligent design. Hasn't there always been good stuff and bad
stuff? A good design would allow you to hard wire the speaker leads
together and go fishing.

Sorry. From a technical standpoint, that is an idiotic statement,
one that has been made before, and disproven time and again. People
like to make statements like "This amp will drive a nail!" etc but
it simply isn't true. It is the nature of bipolar transistors, in
fact any semiconductor, that they cannot carry current much beyond
their rating for more than a split-second. The instantaneous current
demanded by a short-circuit will destroy ANY semiconductor output
device unless that device is being so limited that it cannot produce
music, which is dynamic in nature. Any protection circuit is there
simply to protect the speakers from an amp failure, and to protect
the amp only if the overload isn't too severe. This presumes that
the sensing circuit will sense a large (but not TOO large) current
surge prior to total failure. Any circuit which would really protect
the amp from a short circuit would also protect it from the music.


Mark Z.

I stand corrected. Maybe my ignorance is the reason I'm still
listening to tubes.

Yeah, I was going to mention tubes but I'd already gone on too long...

Tube amps don't like short circuits either, but due to the physical
constuction and current limitations of the tubes themselves, plus the ohmic
resistance of the transformers (small though it is) they won't ordinarily be
damaged by a short, especially one of short duration. McIntosh solid state
models using output transformers are also somewhat less likely to be damaged
by a short.

I need to stop here - I'm a repair tech, not an engineer. If I go on too
long, I'm liable to stray into engineering theory, which I try not to do,
since I'm not qualified, and the real engineering types around here will be
forced to waste time correcting me...

Enjoy your tube stuff ! Have a good one...

Mark Z.

 

[g]

On May 30, 8:39 pm, "Mark D. Zacharias" <spamme...@nonsense.net>
wrote:

Dave wrote:
"Mark D. Zacharias" <spamme...@nonsense.net> wrote in message
news:Q%d7i.6286$C96.4135@newssvr23.news.prodigy.net...
Dave wrote:
The bias diode is essentially two diodes in series. (Sometimes three,
actually). In this case two, looks like. A diode check function of a
DMM would be OK for a static check, and if it became necessary you
could use the DMM to help match a replacement pair of diodes to
replace it with. However, using regular diodes might not work as
well in terms of correctly responding to heat changes.
The proof is in the operation, and in this case that means the actual
voltage drop across the device in-circuit, while theampis running.
Bias diodes opening up is uncommon but it does happen, and when it
does, catastrophe is the result.

In your case the resistors may have burned because of a momentary
short at the speaker wires, etc although this would ordinarily have
destroyed the output transistors as well.

If the bias diode is two diodes in series, why does the parts list
call it a varistor? It's a funky-looking thing that looks like one
of those connectors you put at the end of a wire to connect it to a
screw. Don't think I'd likely find another one. It's physically
screwed to the heatsink the outputs use.

Has technology evolved so that a momentary crossing of speaker wires
could not destroy expensive output transistors? You see all sorts
amps with "protection" circuits in them nowadays and lots ofamp
module IC's which boast both thermal and overcurrent resettable
protection...
I measured D405 vs D406 in circuit with no power applied and the
value, although useless quantitatively, was the same for both
channels. I'll check it in operation when I get all the resistors
replaced (and Q417).
Bonus for me: the one transistor used in thatampwhich I've got in
stock is 2SC945, which matches Q417 the bias transistor. I like BD
Enterprises which you directed me to, they seem to stock all sorts of
transistors nobody else does, or their search facility immediately
suggests an alternative if they don't have the original.

Dave

I was going by the schematic, and had not seen the physical mounting. Of
course the best choice to replace the "diode" would be to order it from
Harmon. I would be comfortable using diodes out of my tool box if necessary
though, using the diode check function of a DMM to help match the voltage
drop of the original (from the other channel, that is).

As I state in another post, output transistors cannot be fully protected
from shorts without also protecting them from the music.

Mark Z.

If the amp is beefy enough, protection circuits will NOT affect the
music.

greg

 

[GregS]

In article <1180615703.212242.304230@k79g2000hse.googlegroups.com>, g <zekor@comcast.net> wrote:

On May 30, 8:39 pm, "Mark D. Zacharias" <spamme...@nonsense.net
wrote:
Dave wrote:
"Mark D. Zacharias" <spamme...@nonsense.net> wrote in message
news:Q%d7i.6286$C96.4135@newssvr23.news.prodigy.net...
Dave wrote:
The bias diode is essentially two diodes in series. (Sometimes three,
actually). In this case two, looks like. A diode check function of a
DMM would be OK for a static check, and if it became necessary you
could use the DMM to help match a replacement pair of diodes to
replace it with. However, using regular diodes might not work as
well in terms of correctly responding to heat changes.
The proof is in the operation, and in this case that means the actual
voltage drop across the device in-circuit, while theampis running.
Bias diodes opening up is uncommon but it does happen, and when it
does, catastrophe is the result.

In your case the resistors may have burned because of a momentary
short at the speaker wires, etc although this would ordinarily have
destroyed the output transistors as well.

If the bias diode is two diodes in series, why does the parts list
call it a varistor? It's a funky-looking thing that looks like one
of those connectors you put at the end of a wire to connect it to a
screw. Don't think I'd likely find another one. It's physically
screwed to the heatsink the outputs use.

Has technology evolved so that a momentary crossing of speaker wires
could not destroy expensive output transistors? You see all sorts
amps with "protection" circuits in them nowadays and lots ofamp
module IC's which boast both thermal and overcurrent resettable
protection...
I measured D405 vs D406 in circuit with no power applied and the
value, although useless quantitatively, was the same for both
channels. I'll check it in operation when I get all the resistors
replaced (and Q417).
Bonus for me: the one transistor used in thatampwhich I've got in
stock is 2SC945, which matches Q417 the bias transistor. I like BD
Enterprises which you directed me to, they seem to stock all sorts of
transistors nobody else does, or their search facility immediately
suggests an alternative if they don't have the original.

Dave

I was going by the schematic, and had not seen the physical mounting. Of
course the best choice to replace the "diode" would be to order it from
Harmon. I would be comfortable using diodes out of my tool box if necessary
though, using the diode check function of a DMM to help match the voltage
drop of the original (from the other channel, that is).

As I state in another post, output transistors cannot be fully protected
from shorts without also protecting them from the music.

Mark Z.

If the amp is beefy enough, protection circuits will NOT affect the
music.

Well, the music wil stop if the protection circuit opperates.

greg

 

[Marra]

On 31 May, 01:35, "Mark D. Zacharias" <spamme...@nonsense.net> wrote:

Smitty Two wrote:
In article <J%f7i.62157$V75.33167@edtnps89>,
"Dave" <dspear9...@yahoo.delete.com> wrote:

Has technology evolved so that a momentary crossing of speaker wires
could not destroy expensive output transistors?

It hasn't as much to do with technological evolution as it has to do
with intelligent design. Hasn't there always been good stuff and bad
stuff? A good design would allow you to hard wire the speaker leads
together and go fishing.

Sorry. From a technical standpoint, that is an idiotic statement, one that
has been made before, and disproven time and again. People like to make
statements like "This amp will drive a nail!" etc but it simply isn't true.
It is the nature of bipolar transistors, in fact any semiconductor, that
they cannot carry current much beyond their rating for more than a
split-second. The instantaneous current demanded by a short-circuit will
destroy ANY semiconductor output device unless that device is being so
limited that it cannot produce music, which is dynamic in nature. Any
protection circuit is there simply to protect the speakers from an amp
failure, and to protect the amp only if the overload isn't too severe. This
presumes that the sensing circuit will sense a large (but not TOO large)
current surge prior to total failure. Any circuit which would really protect
the amp from a short circuit would also protect it from the music.

Mark Z.

This is not always true.
The power supply can only supply so much current.
Any of my designs have MOSFETs that can take more than a shorted PSU.
By the time the MOSFETS have got anywhere near warm the fuses will
have gone.

www.ckp-railways.talktalk.net/pcbcad21.htm

 

[Lionel]

[sci.electronics.repair added]
On Wed, 30 May 2007 18:44:45 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote:

Anyone know how to dismantle and clean an hp3970?

I've developed a foggy looking coating on the _inside_ :-(

Never worked on HP scanners, but I've fixed Canons & various other
brands plenty of times, & the usual steps to dissasemble go something
like this:

* Hold lid by sides & lift until the supports pop out of the slots.

* Look for a retaining strip in the area that was covered by the hinge
of the lid.

* If present, unscrew / unclip to reveal one end of the glass lid.
CAREFULLY lift open end above case & slide out.
* Goto: CLEANING.

* Otherwise, place scanner upside down on SOFT SURFACE, grab a torch,
& look under unit for round screw slots or square/rectangular
retaining-clip slots. Remove screws or 'pop' clips with long,
flatblade screwdriver.

* If it uses clips, it's usually neccessary to apply a little tension
between the halves of the shell while 'popping' the clips/hooks to
keep them released. I use tongue-depressers or similar to keep the
halves from 'clicking' back together while I'm doing the other clips.

When the case is split, it should be easy to figure out how the cover
glass is being retained. Wearing clean gloves, remove glass
*CAREFULLY*.

CLEANING:

* Put on a pair of lint-free white cotton gloves, or a pair of clean
rubber gloves.
* Place glass on clean towel, folded several times.
* Spray Windex or similar ammonia-based glass cleaner on a clean lens
cloth or similar soft, *lint-free* cloth.
* Clean top side with damp cloth, dry with a *different* cloth.
* Flip glass, touching only the sides.
* Clean this side, as above.

* Slide glass slowly & carefully back into the case, in exactly the
reverse of the way you removed it. With some cases, it can be useful
to tie a ribbon or similar around the glass first, so you can support
it with your other hand, so it can't fall inside the case if you slip,
etc. Using your gloved finger, make sure the glass is seated solidly,
& flat, as it's not always obvious, & a bad fit will give you poorly
focussed/blurred scans.

* Without removing your gloves, reassemble the unit.

* Test. (Duh.)

--
W "Some people are alive only because it is illegal to kill them."
. | ,. w ,
\|/ \|/ Perna condita delenda est
---^----^---------------------------------------------------------------

 

[Lionel]

On Fri, 01 Jun 2007 03:06:06 GMT, "Michael A. Terrell"
<mike.terrell@earthlink.net> wrote:

JackShephard wrote:

Glass might look green on edge, but a piece that thin is NOT going to
alter the color of a capture, so standard double strength glass would
surely work just fine, idiot.


Wow, you don't care how many people see how truely stupid you are. I
know a guy that tried 'standard double strength glass' instead of the
optical grade glass. It caused so much distortion in the scanned images
that it was useless, just like you.

Replacement glass for scanners, copiers, etc must be:

1) Optical grade float glass, or you'll get distortion of various
sorts - window glass is unlikely to be flat & even enough.

2) The same thickness as the original, or the optics won't focus
correctly, plus the retaining slot/clips probably won't hold it
securely, or might bow it or crack it during installation.

3) The same (or similar) refractive index as the original, or you risk
getting any - or all - of: poor contrast, lamp flare, or 'ghost'
images, due to internal reflections in the glass.

And yes, Prongy / JackShephard is a useless idiot, but of course you
already knew that. ;^)

--
\___ Proud Cog #1 in the AUK Hate Machine
_(AUK)====:: Do *you* think that you have the Right Stuff?
/='='='='-, Apply TODAY by addressing a gratuitously cruel
(O+O+O+O+O) flame to: "Uncle Fester", C/O soc.singles & AUK.
~^^^^^^^^^~~~^~^^~'~~^'^~~~"~~'"~^~'"~~^~"~'~^'^~^~^^~^~"~^~"'~'"~^~~

 

[g]

On May 3, 11:12 pm, "Mr. Land" <grafton...@yahoo.com> wrote:

On May 2, 6:39 pm, "Dave" <dspear9...@yahoo.delete.com> wrote:



p...@aol.com> wrote in message

news:1178141401.764048.27780@c35g2000hsg.googlegroups.com...

On May 1, 12:42 pm, "Dave" <dspear9...@yahoo.delete.com> wrote:

a)cleaningpots and switches is only the first step. You need to
provide some (slight) amount of lubrication afterwards. 100% volatile
cleaners can cause serious friction after the skunge is removed
rebuilding additional skunge almost instantly. The idea is to exercise
the pot only as long as the cleaner is wet, then stop, thenre-
saturate to rinse out the residue. *AFTER* that, a wee spritz of
lubricating cleaner makes all go smoothly.

Ire-cleaned with a cleaner with lubricant last night.

b) switches are even 'more so' as wear can happen in any of several
ways including breaking of tabs or contact springs, and additional
friction can cause failure. So, same process. Saturate, exercise for a
few cycles whilst saturated, rinse, lubricate.

Did notre-do switches. I will though.

c) Look for broken traces on the boards, look (still) for bad caps. Do
you test the new caps *before* you install them? I have found about
0.5% of new electrolytic caps are bad or sufficiently out of spec to
be problematic. "Badness" typically manifests as intermittents... and
your delay may be related. Or, one you did not replace for whatever
reason...

I don't have an ESR meter. Is testing plain ol' capacitance any help? I'd
like to think it's a capacitor given that that's all I changed out.

d) you may believe that the power-ampsection is clean, but one thing
I have experienced that is quite peculiar but as I have seen it
twice, it cannot be all that rare... an input transistor on the power-
ampside has become sufficiently different from its other-channel mate
that similar-volume signals to it are quite different in output
volume. RARE, and the only way you will catch this is to remove the
questionable transistors and put them either on a scope or tester that
can determine their actual response.

This was an overnight change, so unless the change was mechanically induced
(definitely not ruling that out) I wouldn't be inclined to look there
justyet.

The more I think about it the less likely a pre-ampproblem seems... the
signal goes through primary amplification (a few transisitors) then through
tone controls, subsonic filter, high cut filter, balance control --> power
amp. I've got a switch to bypass the tone control, and switches to bypass
the filters, plus a switch to reverse the channels between pre-ampandamp.
None of these affect theampoutput. If I've got a bad cap in theamp
stages and am getting a DC offset at my outputs, that MAY be engaging the
speaker protection. Or, I suppose, worst case scenario I've baked one of my
giant expensive output transistors. I am assuming the speaker protection
(being two leaded) is a polyswitch. The distorted sound for a second or so
prior to speaker cut-out might match a polyswitch tripping, I don't know as
I've only ever had amps with relay protection (or none) in the past. Do you
know offhand if polyswitches tend to fail? I suppose probably as much as
any other component exposed to variable voltage and current.

I'm going to bypass the preamp section. If I can confirm that the problem
is in theamp, I could a) check DC voltages at all transistors until I find
one that's off or b) start swapping electrolytic capacitors from channel to
channel. there are only four per channel in theampsection.

e) lastly and I have seen this only once and it was A BEAR to find. A
perfectly fine looking 1/2 watt resistor in the signal path had
drifted to 3X its nominal value. How did I find it? Well, every other #
$%^&*( part checked out, so I started measuring resitance "cold"
across both channels and comparing the results component by component.
When I found a difference, I started lifting legs about that point.
And there it was.

Yes I've had several of those; they can try your patience.

Good luck with it.

Thanks, I may just need it.

Peter Wieck
Wyncote, PA

There used to be a spray on the market - can't remember who made it at
the time, might have been GC - it was called "Blue Stuff". I worked
in astereoservice department thru college, and that spray was the
best we could find forcleaningstubbornly noisy pots and switches.
When you sprayed it on it formed a mildly abrasive blue paste, which
would actually scrub the tarnish and dirt off of switch contacts. I
never saw it fail, even with the noisiest, most tarnished switches and
controls. I think it has diatomaceous earth in it.

Anyway, I think TechSpray carries it - might be worth a try
(www.techspray.com)

I just investigated this stuff, in fact I think I ordered some and
have not yet received it. Its been discontinued I think. Yes, I
ordered it two months ago, and it said they had the quanity i ordered.
Glad you brought it up. A recording studio asked me about this stuff,
and they said they depended on it. I know of no other cleaner other
than Cramolin Contaclean, that actually has something in it to
dissolve oxides.

greg

 

[Homer J Simpson]

"Lionel" <usenet@imagenoir.com> wrote in message
news:f3osj0$g34$1@blackhelicopter.databasix.com...

* Otherwise, place scanner upside down on SOFT SURFACE, grab a torch,

Flashlight. A propane torch is too extreme.

 

[Mark D. Zacharias]

Marra wrote:

On 31 May, 01:35, "Mark D. Zacharias" <spamme...@nonsense.net> wrote:
Smitty Two wrote:
In article <J%f7i.62157$V75.33167@edtnps89>,
"Dave" <dspear9...@yahoo.delete.com> wrote:

Has technology evolved so that a momentary crossing of speaker
wires could not destroy expensive output transistors?

It hasn't as much to do with technological evolution as it has to do
with intelligent design. Hasn't there always been good stuff and bad
stuff? A good design would allow you to hard wire the speaker leads
together and go fishing.

Sorry. From a technical standpoint, that is an idiotic statement,
one that has been made before, and disproven time and again. People
like to make statements like "This amp will drive a nail!" etc but
it simply isn't true. It is the nature of bipolar transistors, in
fact any semiconductor, that they cannot carry current much beyond
their rating for more than a split-second. The instantaneous current
demanded by a short-circuit will destroy ANY semiconductor output
device unless that device is being so limited that it cannot produce
music, which is dynamic in nature. Any protection circuit is there
simply to protect the speakers from an amp failure, and to protect
the amp only if the overload isn't too severe. This presumes that
the sensing circuit will sense a large (but not TOO large) current
surge prior to total failure. Any circuit which would really protect
the amp from a short circuit would also protect it from the music.

Mark Z.

This is not always true.
The power supply can only supply so much current.
Any of my designs have MOSFETs that can take more than a shorted PSU.
By the time the MOSFETS have got anywhere near warm the fuses will
have gone.

www.ckp-railways.talktalk.net/pcbcad21.htm

I have an Adcom 5802 in the shop right now with shorted Mosfets which
resulted from just a momentary short at the speaker terminals.

Mark Z.

 

[Mark D. Zacharias]

g wrote:

On May 30, 8:39 pm, "Mark D. Zacharias" <spamme...@nonsense.net
wrote:
Dave wrote:
"Mark D. Zacharias" <spamme...@nonsense.net> wrote in message
news:Q%d7i.6286$C96.4135@newssvr23.news.prodigy.net...
Dave wrote:
The bias diode is essentially two diodes in series. (Sometimes
three, actually). In this case two, looks like. A diode check
function of a DMM would be OK for a static check, and if it became
necessary you could use the DMM to help match a replacement pair
of diodes to replace it with. However, using regular diodes might
not work as well in terms of correctly responding to heat changes.
The proof is in the operation, and in this case that means the
actual voltage drop across the device in-circuit, while theampis
running. Bias diodes opening up is uncommon but it does happen,
and when it does, catastrophe is the result.

In your case the resistors may have burned because of a momentary
short at the speaker wires, etc although this would ordinarily have
destroyed the output transistors as well.

If the bias diode is two diodes in series, why does the parts list
call it a varistor? It's a funky-looking thing that looks like one
of those connectors you put at the end of a wire to connect it to a
screw. Don't think I'd likely find another one. It's physically
screwed to the heatsink the outputs use.

Has technology evolved so that a momentary crossing of speaker wires
could not destroy expensive output transistors? You see all sorts
amps with "protection" circuits in them nowadays and lots ofamp
module IC's which boast both thermal and overcurrent resettable
protection...
I measured D405 vs D406 in circuit with no power applied and the
value, although useless quantitatively, was the same for both
channels. I'll check it in operation when I get all the resistors
replaced (and Q417).
Bonus for me: the one transistor used in thatampwhich I've got in
stock is 2SC945, which matches Q417 the bias transistor. I like BD
Enterprises which you directed me to, they seem to stock all sorts
of transistors nobody else does, or their search facility
immediately suggests an alternative if they don't have the original.

Dave

I was going by the schematic, and had not seen the physical
mounting. Of course the best choice to replace the "diode" would be
to order it from Harmon. I would be comfortable using diodes out of
my tool box if necessary though, using the diode check function of a
DMM to help match the voltage drop of the original (from the other
channel, that is).

As I state in another post, output transistors cannot be fully
protected from shorts without also protecting them from the music.

Mark Z.

If the amp is beefy enough, protection circuits will NOT affect the
music.

greg

Not necessarily affecting the sound, just triggering and shutting the amp
down when the over-current condition is detected. It would only affect the
sound if the amp driving signal is reduced or "soft-clipped" to deal with
the overload, an approach I have never been much impressed with as a
technician. The amps seem to blow up all the same, often along with the
transistors etc used to perform the limiting (old Marantz amps for example).

Mark Z.

 

[Hidalgo Velázquez]

Craigslist

?

--
http://sfaccimma-della-gente.blogspot.com/
http://napolimerda.blogspot.com/

 

[Deeply Filled Mortician]

Make credence recognised that on Tue, 05 Jun 2007 00:19:11 +0200,
Hidalgo Velázquez <hidalgovelazquez@gmail.com> has scripted:

Craigslist

?

Look at the comments. There's a serial spammer out there that's
working hard.
--
---
DFM - http://www.deepfriedmars.com
---
--

 

[Michael Kennedy]

"Homer J Simpson" <nobody@nowhere.com> wrote in message
news:JYY7i.71290$g63.8131@edtnps82...

"Lionel" <usenet@imagenoir.com> wrote in message
news:f3osj0$g34$1@blackhelicopter.databasix.com...

* Otherwise, place scanner upside down on SOFT SURFACE, grab a torch,

Flashlight. A propane torch is too extreme.

That was what first came to my mind as well. I thought he was going to melt
the clips apart.

 

[webpa]

On Jun 8, 2:12 pm, "michelleg...@gmail.com" <michelleg...@gmail.com>
wrote:

Are you coachable, because if you are I have a proven formula that I
have personally tested and it really works? This formula produces
income..., pure and simple.
If you are like me and have tried other businesses... only to fail,
then this is something you'll thank me for.http://www.leveragingonline.com

NO thanks. Stop posting spamshit here...and everywhere else.

 

[Zebra]

Dear All,

I opened the deck today and figured out that a gear on a motor had slipped
outward. I pressed it back and the deck functions. However, it seemed a bit
strange that both side of the deck had the same problem. After a closer
look, I noticed a crack on the gear. Any hints on where to get a
replacement. Below is a link of 2 photos showing the gear before and after
repair -- these are the closest look without taking it apart.

http://hk.pg.photos.yahoo.com/ph/ptongptong/album?.dir=/870escd&.src=ph&.tok=phLn_4GBIUn_PPdk

Furthermore, the decks still functions irradically when pressing the
butttons. Should I look for the ICs or ?? Thanks.

Perpetuus

 

[jakdedert]

Zebra wrote:

Dear All,

I opened the deck today and figured out that a gear on a motor had slipped
outward. I pressed it back and the deck functions. However, it seemed a bit
strange that both side of the deck had the same problem. After a closer
look, I noticed a crack on the gear. Any hints on where to get a
replacement. Below is a link of 2 photos showing the gear before and after
repair -- these are the closest look without taking it apart.

http://hk.pg.photos.yahoo.com/ph/ptongptong/album?.dir=/870escd&.src=ph&.tok=phLn_4GBIUn_PPdk

Photos above do not show enough detail to get any insight into the issue.

Furthermore, the decks still functions irradically when pressing the
butttons. Should I look for the ICs or ?? Thanks.

Perpetuus



Failing a replacement--or reliable repair--of the gear (plus probable

re-engineering in order to prevent recurrence--based on the fact that
the same thing occurred on both decks), no other other fixing is
advisable.

Either fix that problem definitively or don't waste your time polishing
a car with a blown engine.

jak

 

[Jerry G.]

On Jun 11, 10:03 am, "Zebra" <t_perpet...@hotmail.com> wrote:

Dear All,

Try here for Panasonic parts. You will have to order the original
part to fix your cassete machine.

http://www.pasc.panasonic.com/


Jerry G.
======

I opened the deck today and figured out that a gear on a motor had slipped
outward. I pressed it back and the deck functions. However, it seemed a bit
strange that both side of the deck had the same problem. After a closer
look, I noticed a crack on the gear. Any hints on where to get a
replacement. Below is a link of 2 photos showing the gear before and after
repair -- these are the closest look without taking it apart.

http://hk.pg.photos.yahoo.com/ph/ptongptong/album?.dir=/870escd&.src=...

Furthermore, the decks still functions irradically when pressing the
butttons. Should I look for the ICs or ?? Thanks.

Perpetuus

 

[Zebra]

Dear All,

Thanks a lot for your help. The link for panasonic parts does contain some
parts for my deck, but I need to figure out its name first. By the way, I
might just backup some of my favourite tapes into CD or MP3 with it before
disposing it if I could not get the correct parts. Thanks again.

Perpetuus


"Jerry G." <jerryg50@hotmail.com>
???????:1181705304.344474.37940@i13g2000prf.googlegroups.com...

On Jun 11, 10:03 am, "Zebra" <t_perpet...@hotmail.com> wrote:
Dear All,

Try here for Panasonic parts. You will have to order the original
part to fix your cassete machine.

http://www.pasc.panasonic.com/


Jerry G.
======



I opened the deck today and figured out that a gear on a motor had
slipped
outward. I pressed it back and the deck functions. However, it seemed a
bit
strange that both side of the deck had the same problem. After a closer
look, I noticed a crack on the gear. Any hints on where to get a
replacement. Below is a link of 2 photos showing the gear before and
after
repair -- these are the closest look without taking it apart.

http://hk.pg.photos.yahoo.com/ph/ptongptong/album?.dir=/870escd&.src=...

Furthermore, the decks still functions irradically when pressing the
butttons. Should I look for the ICs or ?? Thanks.

Perpetuus

 

[b]

On 13 jun, 07:28, "Zebra" <t_perpet...@hotmail.com> wrote:

Dear All,

Thanks a lot for your help. The link for panasonic parts does contain some
parts for my deck, but I need to figure out its name first. By the way, I
might just backup some of my favourite tapes into CD or MP3 with it before
disposing it if I could not get the correct parts. Thanks again.

Perpetuus

"Jerry G." <jerry...@hotmail.com
???????:1181705304.344474.37...@i13g2000prf.googlegroups.com...

On Jun 11, 10:03 am, "Zebra" <t_perpet...@hotmail.com> wrote:
Dear All,

Try here for Panasonic parts. You will have to order the original
part to fix your cassete machine.

http://www.pasc.panasonic.com/

Jerry G.
======

I opened the deck today and figured out that a gear on a motor had
slipped
outward. I pressed it back and the deck functions. However, it seemed a
bit
strange that both side of the deck had the same problem. After a closer
look, I noticed a crack on the gear. Any hints on where to get a
replacement. Below is a link of 2 photos showing the gear before and
after
repair -- these are the closest look without taking it apart.

http://hk.pg.photos.yahoo.com/ph/ptongptong/album?.dir=/870escd&.src=...

Furthermore, the decks still functions irradically when pressing the
butttons. Should I look for the ICs or ?? Thanks.

Perpetuus

if parts are hard to find, you can remove the gear then try
supergluing it to the motor shaft. mark the shaft with a indelible
marker before removing the gear so you know where exactly to position
it after.

 

[mm]

On Wed, 13 Jun 2007 14:51:20 -0400, "Zephyr" <an address @ some place
..com> wrote:

Hey folks,

I'm curious about power consumption of things like the power supply for my
dell laptop
its and AC/DC adaptor, and when the unit is charging my laptop it gets quite
warm.
from that I infer that its using a fair amount of power.

now, if I leave it plugged into the wall, but remove the laptop, it does
not heat up, but.
there is a little light on it that indicates it is receiving power.
aside from that little light, is it using any significant amount of power?
The label on the unit says the input is 1.5a

same question goes for my cell phone chargers 0.2a

I understand that some of these things do use power constantly, but... how
much?

Good question. Not only the ones with wall warts, those black
"adaptor" boxes that plug into the wall with a cord coming out of
them, but many radios etc. with the transformers inside, have no
switch in the primary of the power transformer, and they are ON all
the time.

For electronic reasons I don't well understand, when there is no
current in the secondary of a transformer, there is higher impedance
in the primary of the transformer, so less current flows even through
the primary. The heat one can feel, that you feel, the waste heat
would be iiac the same percentage of energy used, as when the device
is running and there is current through the secondary.

From your touch, it sounds like the current is a lot lower, but otoh,
it's on all the time if the thing is plugged in, even for things that
are only used an hour a year.

Does anyone know what the percentage is, or how much these things use
when off?

xposted to sci.electronics.repair

I found this link but it doesn't get into the Nitti gritty I was looking
for

http://gizmodo.com/gadgets/gadgets/california-passes-vampire-slayer-act-181497.php

Dave