Toshiba TV29C90 problem; Image fades to black...

[William Sommerwerck]

Let me know what the problem appears to be, and I will pass it along to the
designers.

"Franc Zabkar" <fzabkar@iinternode.on.net> wrote in message
news:l8j8541t3dhhqji6hu5fbh5i95j6tkqinq@4ax.com...

On Sat, 14 Jun 2008 07:02:27 -0700, "William Sommerwerck"
grizzledgeezer@comcast.net> put finger to keyboard and composed:

I work at Microsoft Hardware ...

That's handy to know. I have a wireless MS keyboard which I believe
has a design bug in its firmware. I wonder how one would go about
reporting something like that, or at least talking to a real human
being who understands the problem.

 

[Chungho@zongazonga.zip]

Try www.zdi.com. Min order $100.00

Or try using this search --> 3sk291 "In Stock" <-- to find
other suppliers.


--
--------------------------------- --- -- -
Posted with NewsLeecher v3.8 Final
Web @ http://www.newsleecher.com/?usenet
------------------- ----- ---- -- -

 

[JANA]

Take the computer to a service place where they have the proper tools
for soldering and they do this type of work all the time. This will
avoid you from damaging the mother board. If you cause damage, you will
need a new mother board!

--

JANA
_____


<astroncer@yahoo.com> wrote in message
news:3271315f-dff3-40a0-91e2-11829f986ea0@i36g2000prf.googlegroups.com...
Hi, I had a loose power socket and superglued it and that lasted just
fine for a few months. Then it went out beyond
an ability to glue it again, but still have a occasional power
connection when moving it. I pulled out the motherboard and the solder
on the bottom side of the board where the socket connects, the solder
was burnt away and brittle.

I'm not much of a solderer, just have a cheap soldering iron with a
large tip. Is there a pretty much common method to repair this, I was
thinking of dropping a drop of solder where the solder failed instead
of finding somebody to repair it. Then putting the laptop back
together and see if it works and do a re-superglue of the offending
loose socket.

Thanks for any tips or suggestions. Tools needed, over my head in my
abilities?

It's a compaq presario 1692

Thanks

 

[Mark D. Zacharias]

<corelliansolo@gmail.com> wrote in message
news:c5cb452f-feff-4976-9365-572949c80ff4@e53g2000hsa.googlegroups.com...

Avoid 'rubbing alcohol', unless it is pure isopropyl alcohol,
because it
can leave a residue

Will get the degreaser as recommended, but until that arrives: Would
99% Isopropyl Alcohol solution help remove the WD-40 in the interim,
or would that leave a residue as well?


BTW: Can anyone recommend a good, original JVC parts supplier? This
VCR would not accept certain tapes after a while, and would like to
solve that problem as well, if I can clean out the WD-40 properly.

Andrews Electronics.

800-289-0300


Mark Z.

 

[ian field]

"naza" <naza911@googlemail.com> wrote in message
news:b635b256-fc2a-4ad3-bfa6-bc32d48b24f5@m36g2000hse.googlegroups.com...

I have got a Matsui TV (link:
http://www.currys.co.uk/martprd/store/cur_page.jsp?BV_SessionID=@@@@0622967266.1213531520@@@@&BV_EngineID=ccfhadeegggiimicflgceggdhhmdgmk.0&page=Product&fm=null&sm=null&tm=null&sku=978626&category_oid=)
which I picked up from currys a while back. It has this strange noise
though. When the screen shows White or bright colours it gives out a
high pitched noise, but is silent for black. Is this a fault?

It could be a loose ferrite core in the line O/P transformer or possibly the
line driver transformer, the PSU chopper transformer can also be a suspect.

Opinions vary on what to use but I've found superglue usually does the
trick - or if "a while back" means so recent there's still a warranty, take
it back and complain.

 

[ian field]

"naza" <naza911@googlemail.com> wrote in message
news:b635b256-fc2a-4ad3-bfa6-bc32d48b24f5@m36g2000hse.googlegroups.com...

I have got a Matsui TV (link:
http://www.currys.co.uk/martprd/store/cur_page.jsp?BV_SessionID=@@@@0622967266.1213531520@@@@&BV_EngineID=ccfhadeegggiimicflgceggdhhmdgmk.0&page=Product&fm=null&sm=null&tm=null&sku=978626&category_oid=)
which I picked up from currys a while back. It has this strange noise
though. When the screen shows White or bright colours it gives out a
high pitched noise, but is silent for black. Is this a fault?

It could be a loose ferrite core in the line O/P transformer or possibly the
line driver transformer, the PSU chopper transformer can also be a suspect.

Opinions vary on what to use but I've found superglue usually does the
trick - or if "a while back" means so recent there's still a warranty, take
it back and complain.

 

[DaveM]

"b" <reverend_rogers@yahoo.com> wrote in message
news:bcbc365f-9c14-4fc4-bf42-3f34d6bfb9b6@x35g2000hsb.googlegroups.com...

a friend is having problems with the pump in an outdoor pool.
Apparently the motor ran one day then the next day it would not come
on. mains supply is good. He suspects a capacitor - which seems to be
16uF 400v , from the motor. I've seen it, quite a chunky thing with a
small threaded screw coming out of it for attachment and a plastic
body. it's about the size of the mains filter caps in 1970s t.v.s

I had never seen a 16uF cap before, and I am surprised at this size.
Is it likely to be an electrolytic? I presume replacing this is a
good place to start. Any thoughts?
-B

The capacitor is almost always suspect in case of an AC motor failure, however,
it's not the only thing that can cause problems. As a starting place, I suggest
that you read the FAQ at
http://www.metalwebnews.com/howto/elec-mtr/elec-mtr.html. It will give you some
theory on motor operation and some troubleshooting tips.

If the motor has a centrifugal start switch, then that's the first thing to
check, since it's the easiest thing to get to on your motor. Open the end bell
on the opposite end of the shaft and make sure the contacts are in good
condition. If they are burned or badly pitted, they are probably not making
contact. This will surely prevent the motor from starting.
Next, test the capacitor with an ohmmeter. It should not have a steady low
(less than a few thousand ohms) resistance, but when the meter is first
connected, the reading should read very low, then commence a steady rise in
resistance, ending in extremely high resistance.
Last thing for you to try is check the continuity of the motor's windings. The
web page above will give you a number of possible wiring configurations (you'll
have to determine which applies to your motor).

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

Experience: What you get when you don't get what you want

 

[DaveM]

"b" <reverend_rogers@yahoo.com> wrote in message
news:bcbc365f-9c14-4fc4-bf42-3f34d6bfb9b6@x35g2000hsb.googlegroups.com...

a friend is having problems with the pump in an outdoor pool.
Apparently the motor ran one day then the next day it would not come
on. mains supply is good. He suspects a capacitor - which seems to be
16uF 400v , from the motor. I've seen it, quite a chunky thing with a
small threaded screw coming out of it for attachment and a plastic
body. it's about the size of the mains filter caps in 1970s t.v.s

I had never seen a 16uF cap before, and I am surprised at this size.
Is it likely to be an electrolytic? I presume replacing this is a
good place to start. Any thoughts?
-B

The capacitor is almost always suspect in case of an AC motor failure, however,
it's not the only thing that can cause problems. As a starting place, I suggest
that you read the FAQ at
http://www.metalwebnews.com/howto/elec-mtr/elec-mtr.html. It will give you some
theory on motor operation and some troubleshooting tips.

If the motor has a centrifugal start switch, then that's the first thing to
check, since it's the easiest thing to get to on your motor. Open the end bell
on the opposite end of the shaft and make sure the contacts are in good
condition. If they are burned or badly pitted, they are probably not making
contact. This will surely prevent the motor from starting.
Next, test the capacitor with an ohmmeter. It should not have a steady low
(less than a few thousand ohms) resistance, but when the meter is first
connected, the reading should read very low, then commence a steady rise in
resistance, ending in extremely high resistance.
Last thing for you to try is check the continuity of the motor's windings. The
web page above will give you a number of possible wiring configurations (you'll
have to determine which applies to your motor).

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

Experience: What you get when you don't get what you want

 

[Michael Kennedy]

"ll" <barn104_1999@yahoo.com> wrote in message
news:fe5bc90e-d919-4506-b880-b93c3653bf6a@a1g2000hsb.googlegroups.com...

Hi,
I am trying to locate the soft vinyl covers for the blade-style,
female ("Lucar") connectors. I have only located them at a British
firm, although the shipping would be prohibitive.
Here's a link to them, about halfway down the page:

http://www.maplin.co.uk/Search.aspx?MenuNo=12326&MenuName=Crimp+Terminals&FromMenu=y&doy=search

Does anyone know if these might be available elsewhere?

Thanks,
Louis

Where are you located?

 

[bz]

corelliansolo@gmail.com wrote in news:c5cb452f-feff-4976-9365-572949c80ff4
@e53g2000hsa.googlegroups.com:

Avoid 'rubbing alcohol', unless it is pure isopropyl alcohol,
because it
can leave a residue

Will get the degreaser as recommended, but until that arrives: Would
99% Isopropyl Alcohol solution help remove the WD-40 in the interim,
or would that leave a residue as well?

Put a few drops on a clean [horizontal] piece of window glass or mirror and
let it dry.

See if there is any residue left.

BTW: Can anyone recommend a good, original JVC parts supplier? This
VCR would not accept certain tapes after a while, and would like to
solve that problem as well, if I can clean out the WD-40 properly.

--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+ser@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap

 

[isw]

In article <4854C620.A120E8FF@hotmail.com>,
Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote:

franco wrote:

Eeyore wrote:
franco wrote:
I have a Korean made Sherwood receiver circa 1980 that distorts on the
right channel only:
with all inputs (eliminating the sources);
with any set of speakers (not the speakers);
at all volumes (eliminating things before the volume knob);
with the headphones (eliminating the power stage?).

No, the headphones will normally be run from the 'power stage'.
not the preamp stage?

Not usually.


Does anyone have any advice troubleshooting this? I'm comfortable
replacing electronic components in circuit boards (when I say me I
mean my electronic savvy friend who is helping me out, He just
replaced leaky looking 1000u cap, but it didn't solve the problem) but
have no experience with stereo troubleshooting and would like to
attempt to fix this myself.

It's not difficult in principle. Do you have experience troubleshooting
other electronics aside from audio ?
some guitar tube amplifier stuff (very simple compared to this); my
friend helping me has experience in TVs and microwave ovens.

Ok, well an perienced tech would know roughly where to probe without a
detailed schematic but it looks like you'll need one of those at minimum.

You have a perfectly functioning amp right there (the other channel);
why not just compare and contrast? It's even a good source for parts to
swap...

Isaac

 

[DaveM]

"JR North" <junkjasonrnorth@bigfoot.com> wrote in message
news:ubjb54lsp0dm7sd9n13cst2kp82jhn5cvs@4ax.com...

I bought one of these on Ebay:
http://cgi.ebay.com/NEW-soldering-STATION-SOLDER-IRON-50W-Extra-tip_W0QQitemZ290238359950QQihZ019QQcategoryZ109556QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
it works well.
The box says Sydney Electronic Tools and also shows 3 sets of
replacement tips 5-7 each in various sizes and configs on the box
These are .187" shank ferrule mounted tips.No instructions or company
info in the box. (don't need any Ebay finger-wagging). The seller is
no help. Can't find the company on Google(prolly Chinese)-just get
loads of Sydney, Australia links and 'tips on soldering' . Other links
for known brands like Weller don't offer a'kit' of tips, just
ploddingly large lists of individual tips, and don't list the shank
dia alot of the time.
Anyone have anything helpful? thanks
JR
HOME PAGE:
http://www.seanet.com/~jasonrnorth
--------------------------------------------------

Your soldering station is exactly the same as the Tenma unit here
(http://www.mcmelectronics.com/product/21-7945), just with a different brand
name. In fact, I've seen these same units being sold by a number of vendors.
MCM has extra tips and sponges for the unit. The tip shank diameter is 0.187",
same as yours. Tips are sold individually.
I bought one of these stations a few months ago when they were on sale at around
$13 USD. It's a bit slow to heat up, but seems to do the job adequately, even
on connections to a large ground place and connections to metal chassis.

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

Experience: What you get when you don't get what you want

 

[bz]

astroncer@yahoo.com wrote in
news:ddb01f63-4a37-4ee2-88d8-9b0fa8ed879d@f36g2000hsa.googlegroups.com:

bz wrote:
stratus46@yahoo.com wrote in news:0f0e8190-5002-4df7-a522-d77de45c1a20
@v1g2000pra.googlegroups.com:

On Jun 14, 3:34�am, bz <bz+...@ch100-5.chem.lsu.edu> wrote:
snip

Buy a soldering iron that is the right size at radio-shack.
Could be cheap, provided you practice, a lot, soldering on old PCB
boards.

Fix your board yourself.

Use GOOD solder 63/37 NOT 60/40.

60/40 is _bad_ solder ?

Yes. It passes through the 'plastic' stage during cooling. Do NOT
jiggle o
r
you get a cold solder joint.
It melts at a higher temperature. Harder to get melted and get good
solder

flow.

63/37 is _that_ much better?

Yes. Get a eutectic solder. [melts at the minimum temp for an alloy of
those metals].

Or did you mean
40/60 which _is_ bad solder ?

50/50 is worse than 60/40 and 40/60 is even worse.
[bad and good in relation to electronics usage. If you are a plumber,
50/5
0
might be better for your work.]

I have 60/40, will that work OK though? This computer is a 733Mhz
processor so it's not modern.

The age of the processor doesn't matter. What does matter is the fact that
it is much easier to make a good solder joint if you use good solder and
much easier to make a bad one if you use bad solder.

If you're patient with eBay, you can get a Metcal in parts for <$100.
Bought 6 so far for at work. After using a Metcal you won't want to
use a Radio Shack soldering tusk.

A GOOD, temperature controlled, soldering iron is, OF COURSE, better
than
a
cheap iron.




--
bz 73 de N5BZ k

Thanks for the replies to this post.

It still has solder there, do I need to remove it?

No, probably not. But if there is too much solder after you get done, you
might want to remove some.

You can use solder braid or a solder sucker to remove excess solder.
Radioshack has an inexpensive de-soldering iron that works very well for
me for removing most parts undamaged.

I'll post a few semi-viewable pictures.

--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+ser@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap

 

[bz]

astroncer@yahoo.com wrote in
news:ddb01f63-4a37-4ee2-88d8-9b0fa8ed879d@f36g2000hsa.googlegroups.com:

bz wrote:
stratus46@yahoo.com wrote in news:0f0e8190-5002-4df7-a522-d77de45c1a20
@v1g2000pra.googlegroups.com:

On Jun 14, 3:34�am, bz <bz+...@ch100-5.chem.lsu.edu> wrote:
snip

Buy a soldering iron that is the right size at radio-shack.
Could be cheap, provided you practice, a lot, soldering on old PCB
boards.

Fix your board yourself.

Use GOOD solder 63/37 NOT 60/40.

60/40 is _bad_ solder ?

Yes. It passes through the 'plastic' stage during cooling. Do NOT
jiggle o
r
you get a cold solder joint.
It melts at a higher temperature. Harder to get melted and get good
solder

flow.

63/37 is _that_ much better?

Yes. Get a eutectic solder. [melts at the minimum temp for an alloy of
those metals].

Or did you mean
40/60 which _is_ bad solder ?

50/50 is worse than 60/40 and 40/60 is even worse.
[bad and good in relation to electronics usage. If you are a plumber,
50/5
0
might be better for your work.]

I have 60/40, will that work OK though? This computer is a 733Mhz
processor so it's not modern.

The age of the processor doesn't matter. What does matter is the fact that
it is much easier to make a good solder joint if you use good solder and
much easier to make a bad one if you use bad solder.

If you're patient with eBay, you can get a Metcal in parts for <$100.
Bought 6 so far for at work. After using a Metcal you won't want to
use a Radio Shack soldering tusk.

A GOOD, temperature controlled, soldering iron is, OF COURSE, better
than
a
cheap iron.




--
bz 73 de N5BZ k

Thanks for the replies to this post.

It still has solder there, do I need to remove it?

No, probably not. But if there is too much solder after you get done, you
might want to remove some.

You can use solder braid or a solder sucker to remove excess solder.
Radioshack has an inexpensive de-soldering iron that works very well for
me for removing most parts undamaged.

I'll post a few semi-viewable pictures.

--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+ser@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap

 

[bz]

astroncer1@yahoo.com wrote in news:33924271-df8c-4227-b30c-a2e8f9528fdc@
56g2000hsm.googlegroups.com:

Hi, here they are

It's right under L50, note the existing solder, I will try to clean it
off. What is it called, from the solder in the first picture left of
the L59, trace? Anyway under magnification that looks good. So would
this be the only place that needs the solder?

I don't know what you have there to the left of L50. It could be corrosion
or glue or something spilled on the board.
There are at least two tabs on that power jack that need to be resoldered.
One near the L50 and the other at the right end of the large silver area.

The third tab, near the edge of the board, may also need to be resoldered.

I would remove the solder on that tab and remove the connector from the
board, clean around each of the holes in the board and clean each solder
tab, replace the connector and solder.

But it would be a very good idea for you to practice on some old circuit
boards first.
You should be able to find an old computer or tv or ... electronic device
sitting by the trash cans.
Or go by a repair shop and ask if they have some trash boards that they
will give you so you can practice soldering.

You might even get them to give you some lessons or at least let you watch.

http://315chan.org/n3rd/src/121358542179.jpg
http://315chan.org/n3rd/src/121358475480.jpg
http://315chan.org/n3rd/src/121358489650.jpg

Thanks for comments, suggestions.

-- lsu
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+nanae@ch100-5.chem.lsu.edu

 

[bz]

astroncer1@yahoo.com wrote in news:33924271-df8c-4227-b30c-a2e8f9528fdc@
56g2000hsm.googlegroups.com:

Hi, here they are

It's right under L50, note the existing solder, I will try to clean it
off. What is it called, from the solder in the first picture left of
the L59, trace? Anyway under magnification that looks good. So would
this be the only place that needs the solder?

I don't know what you have there to the left of L50. It could be corrosion
or glue or something spilled on the board.
There are at least two tabs on that power jack that need to be resoldered.
One near the L50 and the other at the right end of the large silver area.

The third tab, near the edge of the board, may also need to be resoldered.

I would remove the solder on that tab and remove the connector from the
board, clean around each of the holes in the board and clean each solder
tab, replace the connector and solder.

But it would be a very good idea for you to practice on some old circuit
boards first.
You should be able to find an old computer or tv or ... electronic device
sitting by the trash cans.
Or go by a repair shop and ask if they have some trash boards that they
will give you so you can practice soldering.

You might even get them to give you some lessons or at least let you watch.

http://315chan.org/n3rd/src/121358542179.jpg
http://315chan.org/n3rd/src/121358475480.jpg
http://315chan.org/n3rd/src/121358489650.jpg

Thanks for comments, suggestions.

-- lsu
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+nanae@ch100-5.chem.lsu.edu

 

[Jim Yanik]

"DaveM" <masondg4499@comcast99.net> wrote in
news:aNadnWBnwdUmbcjVnZ2dnUVZ_o7inZ2d@comcast.com:

"JR North" <junkjasonrnorth@bigfoot.com> wrote in message
news:ubjb54lsp0dm7sd9n13cst2kp82jhn5cvs@4ax.com...
I bought one of these on Ebay:
http://cgi.ebay.com/NEW-soldering-STATION-SOLDER-IRON-50W-Extra-tip_W0
QQitemZ290238359950QQihZ019QQcategoryZ109556QQssPageNameZWDVWQQrdZ1QQc
mdZViewItem it works well.
The box says Sydney Electronic Tools and also shows 3 sets of
replacement tips 5-7 each in various sizes and configs on the box
These are .187" shank ferrule mounted tips.No instructions or company
info in the box. (don't need any Ebay finger-wagging). The seller is
no help. Can't find the company on Google(prolly Chinese)-just get
loads of Sydney, Australia links and 'tips on soldering' . Other
links for known brands like Weller don't offer a'kit' of tips, just
ploddingly large lists of individual tips, and don't list the shank
dia alot of the time.
Anyone have anything helpful? thanks
JR
HOME PAGE:
http://www.seanet.com/~jasonrnorth
--------------------------------------------------


Your soldering station is exactly the same as the Tenma unit here
(http://www.mcmelectronics.com/product/21-7945), just with a different
brand name. In fact, I've seen these same units being sold by a
number of vendors. MCM has extra tips and sponges for the unit. The
tip shank diameter is 0.187", same as yours. Tips are sold
individually. I bought one of these stations a few months ago when
they were on sale at around $13 USD. It's a bit slow to heat up, but
seems to do the job adequately, even on connections to a large ground
place and connections to metal chassis.

I think that's a Weller product;WLC100


http://www.cooperhandtools.com/brands/CF_Files/model_detail.cfm?upc=0371030
59963

http://www.cooperhandtools.com/onlinecatalog/images/WLC100_100.jpg

--
Jim Yanik
jyanik
at
kua.net

 

Sam Goldwasser wrote:

I have been a member in good standing with eBay since 1999. As readers
of Sam's Laser FAQ are probably aware, I have acquired a large number of
lasers and related items on eBay, most at bargain basement prices. All in
all I have been very satisfied with the eBay experience. Until now.

For a blow-by-blow saga of what I'm experiencing now, please go to

http://repairfaq.cis.upenn.edu/Misc/ebayhorror1.htm

I will be updating this as it plays out. I expect the outcome to be
satisfactory, but the route it's taking is like one of those nightmares
where you're trapped on a 15 dimensional mobius strip.

Comments welcome!

A Stockholder, and Merchant, Loses Confidence in eBay
http://seekingalpha.com/article/81353-a-stockholder-and-merchant-loses-confidence-in-ebay
(Small eBay seller had his account (with over 400 positive feedbacks)
suspended because of one negative feedback.)

A new test case of the DMCA--this time over an eBay auction
http://news.cnet.com/8301-10787_3-9949976-60.html
(Totally bogus accusation against eBay seller -- eBay suspends him.)

 

Sam Goldwasser wrote:

I have been a member in good standing with eBay since 1999. As readers
of Sam's Laser FAQ are probably aware, I have acquired a large number of
lasers and related items on eBay, most at bargain basement prices. All in
all I have been very satisfied with the eBay experience. Until now.

For a blow-by-blow saga of what I'm experiencing now, please go to

http://repairfaq.cis.upenn.edu/Misc/ebayhorror1.htm

I will be updating this as it plays out. I expect the outcome to be
satisfactory, but the route it's taking is like one of those nightmares
where you're trapped on a 15 dimensional mobius strip.

Comments welcome!

A Stockholder, and Merchant, Loses Confidence in eBay
http://seekingalpha.com/article/81353-a-stockholder-and-merchant-loses-confidence-in-ebay
(Small eBay seller had his account (with over 400 positive feedbacks)
suspended because of one negative feedback.)

A new test case of the DMCA--this time over an eBay auction
http://news.cnet.com/8301-10787_3-9949976-60.html
(Totally bogus accusation against eBay seller -- eBay suspends him.)

 

[N_Cook]

Ron(UK) <ron@lunevalleyaudio.com> wrote in message
news:EcOdnfhYQvejds7VRVnyhwA@bt.com...

Fleetie wrote:
The obvious choice, as Mr Cook says, is a crystal earpiece.

With one of those, the OP won't even need to make 2 connections;
just touching the tip of the jack plug on the conductor that's
oscillating at a few kHz and a few volts will be enough to make
it faintly audible with careful listening.


One of the most useful bit of kit in my toolbox is a device I made
myself some 35 or so years ago. It`s a crystal earpiece with one wire
terminated in a croc clip and the other in a probe made from an old
ballpoint pen and a brass nail, there`s a capacitor in series to provide
DC blocking.
With this simple device I can trace audio through a circuit- from the
output of a crystal pick-up to several hundreds watts, I can detect
digital pulses, hear hum on a DC supply, etc. etc.

Ron(UK)

I must do the same sometime.
I've always picked up the standard earpiece and a pair of croc-leads and a
needle point rather than making a purpose built tool. Adding in a HV cap if
monitoring for noisy HT lines.
A scope would not show any more info in that situation and avoids
possibility of connecting scope up, in DC mode, set on 1mV/cm or HT pulse
transmitted through internal cap of scope, on a low range, and out goes dual
gate FET or whatever.

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