Toshiba TV29C90 problem; Image fades to black...

[Ol' Duffer]

In article <e79927cb-9552-41f4-81e9-0c380ce099b0
@f36g2000hsa.googlegroups.com>, hwbosshoss@comcast.net says...

I have revised the schematic further by adding the voltages at the
base of Q205 and collector of Q204....

http://i240.photobucket.com/albums/ff58/eadgbe123/amplifier-2.jpg

I guess I don't have enough equipment to fix this problem. I can't
afford a 'scope right now. This will have to go on a shelf until I
can deal with it.

You don't need a scope for this one, just DC meter and brain power.
For the output transistors, Q207 base should be about one Volt higher
than Q208 base. If not, either Q206 is shorted or Q205 is not sourcing
current. If I can believe the voltages you show on Q205, it probably
has an open collector.

 

[bz]

"James" <james@nospam.com> wrote in
news:6eSdnTosdIIDSZDVnZ2dnUVZ_v-hnZ2d@earthlink.com:

You might want to look at pc scopes. Or ebay. If all you are doing is
audio and possibly lower rf frequencies there are lots of decent used
scopes on ebay.

"EADGBE" <hwbosshoss@comcast.net> wrote in message
news:e79927cb-9552-41f4-81e9-0c380ce099b0@f36g2000hsa.googlegroups.com...

I have revised the schematic further by adding the voltages at the
base of Q205 and collector of Q204....

http://i240.photobucket.com/albums/ff58/eadgbe123/amplifier-2.jpg

I guess I don't have enough equipment to fix this problem. I can't
afford a 'scope right now. This will have to go on a shelf until I
can deal with it.

You might download a program such as waveview or spectragram (demo versions
of many programs are available), make yourself a resistor divider probe and
look at the waveforms with your computer.

http://www.waveviewdaq.com/
http://www.neasmn.org/ben/software/gram517.zip






--
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

 

[Arny Krueger]

"EADGBE" <hwbosshoss@comcast.net> wrote in message
news:7a5f62ce-00ec-4fac-84f3-838743faa613@e67g2000hsa.googlegroups.com

In the interest of clarification, I have added some
information to the schematic of the tape deck headphone
amp that I'm having problems with.

Some circuit paths are now labeled:

http://i240.photobucket.com/albums/ff58/eadgbe123/amplifier-1.jpg

As always, the points at which voltage readings are
marked with a star are NOT producing the voltage
indicated. The +7V location is measuring 131mV instead.
The other two points where a star is indicated are
measuring between 20mV and 30mV (fluctuating slightly).

I am starting to think that a circuit OUTSIDE of this
circuit might be at fault, because NOTHING inside of this
circuit seems to be faulty...but the darn thing still
WILL NOT work.

Have you followed the recommended procedure for debugging direct-coupled
circuits like this?

Step 1 - remove all transistors and check them for shorts and opens out of
the circuit. An ohmeter usually suffices.

 

[John Phillips]

On 2008-04-22, EADGBE <hwbosshoss@comcast.net> wrote:

I have revised the schematic further by adding the voltages at the
base of Q205 and collector of Q204....

http://i240.photobucket.com/albums/ff58/eadgbe123/amplifier-2.jpg

I guess I don't have enough equipment to fix this problem. I can't
afford a 'scope right now. This will have to go on a shelf until I
can deal with it.

If I understand this correctly the nominally 5.8 V point on Q208 base
is close to 0 V but the output node is OK at +6.4 V.

If that's right, Q208's VBE plus the drop across the lower 3.3 ohm output
resistor is about 6.4 volts rather than about 0.6 V. That can't be
so unless the lower 3.3 ohm resistor is open circuit, or it has 6.4 V
across it and is boiling hot, or Q208 is open circuit B-E.


--
John Phillips

 

[John Phillips]

On 2008-04-22, EADGBE <hwbosshoss@comcast.net> wrote:

On Apr 22, 10:08 am, John Phillips <news0...@DontUseThis.mainly.me.uk
wrote:

If I understand this correctly the nominally 5.8 V point on Q208 base
is close to 0 V but the output node is OK at +6.4 V.


Actually, I am measuring +7.3V at the junction of the two 3.3 ohm
resistors between Q207 and Q208.

And +20 - +30 mV at the base of Q208 from a previous point if I am
correct?

What's the voltage across the B-E of Q208 and what's the voltage across
the lower 3.3 ohm resistor?

--
John Phillips

 

[GregS]

In article <7a5f62ce-00ec-4fac-84f3-838743faa613@e67g2000hsa.googlegroups.com>, EADGBE <hwbosshoss@comcast.net> wrote:

In the interest of clarification, I have added some information to the
schematic of the tape deck headphone amp that I'm having problems
with.

Some circuit paths are now labeled:

http://i240.photobucket.com/albums/ff58/eadgbe123/amplifier-1.jpg

As always, the points at which voltage readings are marked with a star
are NOT producing the voltage indicated. The +7V location is
measuring 131mV instead. The other two points where a star is
indicated are measuring between 20mV and 30mV (fluctuating slightly).

I am starting to think that a circuit OUTSIDE of this circuit might be
at fault, because NOTHING inside of this circuit seems to be
faulty...but the darn thing still WILL NOT work.

Where did you get this diagram. Is it completely from scratch ?


greg

 

[GregS]

In article <bb9d022f-3212-41a4-b455-e8d7f6cbd09c@u69g2000hse.googlegroups.com>, EADGBE <hwbosshoss@comcast.net> wrote:

On Apr 22, 10:34 am, zekfr...@zekfrivolous.com (GregS) wrote:

Where did you get this diagram. Is it completely from scratch ?


Greg:

No, it was copied, carefully, from the original schematic. I would
have scanned the original schematic, but it is very fuzzy. I did
check my schematic against the other channel's schematic, which was a
bit clearer but did not have the expected voltages indicated, and was
cluttered with the actual component values.

I have checked, re-checked, and RE-checked the accuracy of my hand-
drawn schematic, comparing it to the original, and there are no
mistakes.

The emitter of Q204 has a strange DC path. The amplifier appears
non inverting. What is the voltage on Q204 collector ?

greg

 

[GregS]

In article <40eed3b4-a4d3-4f7e-a687-0a1e0cb9d398@2g2000hsn.googlegroups.com>, EADGBE <hwbosshoss@comcast.net> wrote:

I have just discovered that the voltage measured directly at the
emitter leg of Q208 is a NEGATIVE voltage that fluctuates anywhere
from -300mV to -16mV.

Thats no good. It seemed most was OK, and I imagined you have no scope.
I was going to suggest injecting a signal at the bases of the imput stage. Holding
a metal probe with your hand should give equal sounds from left and right on corresponding
points of each amp.

You are going to have to check the Q208 more thoroughly.

greg

 

[John Phillips]

On 2008-04-22, EADGBE <hwbosshoss@comcast.net> wrote:

I have just discovered that the voltage measured directly at the
emitter leg of Q208 is a NEGATIVE voltage that fluctuates anywhere
from -300mV to -16mV.

By subtraction from the 7.3 V you said was present at the junction of the
two 3.3 ohm resistors there's nominally 7.3 to 7.6 V across the lower one.

So it looks like:

- that lower 3.3 ohm resistor is open circuit; or

- it's dissipating about 16 watts because of another fault and presumably
getting rather hot which may lead to it going o/c soon (depending
on its power rating which I would guess doesn't support a 16 watt
dissipation); or

- it isn't actually connected to the emitter of Q208 so check the
soldering.

--
John Phillips

 

[Richard Crowley]

"EADGBE" wrote ...

I have just discovered that the voltage measured directly at the
emitter leg of Q208 is a NEGATIVE voltage that fluctuates anywhere
from -300mV to -16mV.

You show the collector of Q208 as being ground.
Is that same ground not the reference for all your
reported voltage measurements. How could it
possibly be negative? There are no sources of
anything below ground shown in your schematic.

What is the voltage on the "to volume control pcb"
node at the bottom left corner of the circuit? Is it
ground/zero? Is that node *really* disconnected
from the rest of the ground reference (collector of
Q208, bottom of the 680 resistor, etc.)? It seems
like it ought to be ground, but you show it as a
separate node.

It seems suspicious that the base of Q204 is measured
to be the proper voltage, but the collector seems to
be pretty much up at the supply rail. That indicated to
me that Q204 isn't conducting properly and preventing
proper bias on Q205.

We have asked you several times about measuring the
equivalent nodes in the other (working) side, but you
seem to have ignored this valuable source of information
about how a proper circuit behaves.

 

[James Sweet]

"James" <james@nospam.com> wrote in message
news:6eSdnTosdIIDSZDVnZ2dnUVZ_v-hnZ2d@earthlink.com...

You might want to look at pc scopes. Or ebay. If all you are doing is
audio and possibly lower rf frequencies there are lots of decent used
scopes on ebay.

Last swap meet I went to I saw at least half a dozen scopes under 10 bucks.
A couple of them were even decent semi-modern looking solid state things,
probably 10-15 MHz, so this stuff does turn up.

 

[Mike S]

The last thing you should do is replace the power supply board. There's a
good chance something else in the TV may have caused a short or heavy load
on the power supply, and the new one would be blown.
Also it is very unlikely you could buy the board, or the price would be
outrageous. It is possible your convergence amp circuit has failed, this
should be tested/repaired first. Then the power supply should be
troubleshot and repaired.
Also, if you try to use adjustments in the service menu, or manual
adjustment of any kind to converge the image, your results are likely to be
very poor and unwatchable. Then when the TV is correctly repaired, it may
take HOURS longer to realign all the settings you have changed. Those
settings and/or adjustments are meant to fine-tune the picture when the
circuit is working correctly.

"eganders" <eganders@yahoo.com> wrote in message
news:aa397c98-b381-4f0c-a925-4491af3cc75d@t54g2000hsg.googlegroups.com...

On Apr 22, 6:46 am, "Art" <plotsl...@hotmail.com> wrote:
Time to actually get out the service manual and find out what particular
voltage to the convergence circuit you have lost, and what caused that
failure.

Check the convergence power supply circuitry and the main supply to that
area. Probable items within the convergence correction circuitry have
been
damaged either by coolant contaminate which you did not address
previously,
or just component failure. Any way, you need to determine if proper
operational potentials are available to that circuit then determine your
next course of action.
"Lance Dyer" <dy...@sasktel.net> wrote in message

news:wvCdnQZslLvl_ZDVnZ2dnUVZ_ternZ2d@sasktel...

time for some new convergence amps and resistors

"eganders" <egand...@yahoo.com> wrote in message
news:494602f5-bf32-490b-86e2-f4449960009b@a70g2000hsh.googlegroups.com...
On Apr 21, 7:37 pm, eganders <egand...@yahoo.com> wrote:
My RCA rear projection TV has worked well after help from you TV
service people in January, 2005. It has
a chassis number of PTK195AC and is model P60812BL

At that time I found that the surface of the PC boards had some of the
coolent and other debris which I cleaned and that fixed the problem.

Coming home from vacation today, the main fuse from the AC input
failed. Upon replacing it, the convergence is all messed up. I went
into the service mode using the front panel as the service manual
describes, I can't seem to get the grid pattern that I got back in
2005. Can anyone tell me

1. What typically goes wrong when the main fuse blows and the picture
goes out of adjustment

2. How do you get into the built-in geometric alignment grid pattern?

I am into the service mode, but it does not seem to have any pattern
except the Pfor parameter) and V (for parameter value): on the
screen.

I would like to nurse this TV along for a while. It has given good
service and I have no reason to replace it other than the present
problem. I really don't want to get into it deeply. For example, I
would prefer NOT to get a chipper checker or have to hook an
oscilloscope to it.

sci.electronics.repair

Here is a photo of the problem

http://img.photobucket.com/albums/v384/eganders/60inchConvergence100_...

OK...

I checked the voltages out of J19701 connector from the power supply
to the convergence board. They are not to specification (at all).

pin 1 should be -45, is -1.8
pin 2 should be -15, is -1.9
pin 3 gnd
pin 4 should be +23, is +23.3
pin 5 should be +15, is 0
pin 6 should be -45, is 1.7

If the plug is pulled going to P19304, all the voltages go to 0 volts
at J19701 on the power supply board. The service manual says to
"disconnect power supply". I took that to mean pull J19701. I assume
that the power board is bad. My question is..
Was the board blown by the load of something wrong on the convergence
board, or just a bad component. I checked the input diode bridge and
it seems to be OK. I would guess I should replace the power supply
board. I wonder how much that is? I would hate to blow it after
changing it out. What are the chances of that?

 

[David Farber]

"EADGBE" <hwbosshoss@comcast.net> wrote in message
news:7a5f62ce-00ec-4fac-84f3-838743faa613@e67g2000hsa.googlegroups.com...

In the interest of clarification, I have added some information to the
schematic of the tape deck headphone amp that I'm having problems
with.

Some circuit paths are now labeled:

http://i240.photobucket.com/albums/ff58/eadgbe123/amplifier-1.jpg

As always, the points at which voltage readings are marked with a star
are NOT producing the voltage indicated. The +7V location is
measuring 131mV instead. The other two points where a star is
indicated are measuring between 20mV and 30mV (fluctuating slightly).

I am starting to think that a circuit OUTSIDE of this circuit might be
at fault, because NOTHING inside of this circuit seems to be
faulty...but the darn thing still WILL NOT work.

I haven't read every follow up message but have you tried removing the
electrolytic caps and retesting the d.c.? I've seen the d.c. stability been
thrown off in many amps due to bad coupling caps.

Good luck.
--
David Farber
David Farber's Service Center
L.A., CA

 

[GregS]

In article <45a191ab-6055-45f6-ba4f-acfc1ae69e11@a22g2000hsc.googlegroups.com>, EADGBE <hwbosshoss@comcast.net> wrote:

.....And I should point out that ALL measurements taken in both
channels were obtained using chassis ground.

I completely missed the star explanation. Why not put measured voltages there.
What is the voltage at collector Q204 on other channel.
Q205 doesn't seem to be conducting much.

greg

 

[Dr.Hal0nf1rŁ$]

§ńühw¤Łf wrote:

On Mon, 21 Apr 2008 23:32:32 +0100
"Dr.Hal0nf1rŁ$" <femail@nospam.kustomkomputa.co.uk.invalid> wrote:

§ńühw¤Łf wrote:
On Sun, 20 Apr 2008 22:15:06 +0100
"Dr.Hal0nf1rŁ$" <femail@nospam.kustomkomputa.co.uk.invalid> wrote:

§ńühw¤Łf wrote:
On Sat, 19 Apr 2008 15:34:16 -0700
Aratzio <a6ahlyv02@sneakemail.com> wrote:

On Sat, 19 Apr 2008 16:09:53 -0500, in the land of
alt.usenet.kooks, snuhwolf@netscape.net (§ńühw¤Łf) got double
secret probation for writing:

Aratzio <a6ahlyv02@sneakemail.com> clouded the waters of pure
thought with:
On Sat, 19 Apr 2008 09:01:56 -0700, in the land of
alt.usenet.kooks, §ńühw¤Łf <snuhwolf@netscape.net> got double
secret probation for writing:

On Sat, 19 Apr 2008 13:35:53 +1000
"Kadaitcha Man" <nospam.nospam.nospam@gmail.com> wrote:

"Aratzio" <a6ahlyv02@sneakemail.com> wrote in message
news:9opi0456deigk7ihd4bq4mq3u9mar9tha3@4ax.com...
On Sat, 19 Apr 2008 13:26:03 +1000, in the land of
alt.usenet.kooks, "Kadaitcha Man"
nospam.nospam.nospam@gmail.com> got double secret probation
for writing:

"Butch Haynes" <butch@huntsville> wrote in message
news:zbmdnUfjYIjDTZXVnZ2dnUVZ_gWdnZ2d@comcast.com...
radiant_x@outgun.com> wrote in message
news:293e3140-e027-496c-89d8-27906e8991f7@t54g2000hsg.googlegroups.com...

I recently installed a DVD drive into my PC. (2 days
ago.) Since then, I get spontaneous power loss
periodically - sometimes seconds after booting, other
times after hours of operation. I've tried replacing the
power supply, and I've tried removing all my hardware
(other than RAM), so I'm thinking it must be motherboard
related.

Unplug/replug all power and data connections. That way,
the errant loose one will be fixed and your problem will
be resolved.

BWAHAHAHAHAHAHAHAHAHAHAHAHA!

Tech support by feng shui.

"I've tried removing all my hardware(other than RAM)"

Do none of them understand what that entails?


None of them understand anything.

I go toetally on into-ition.
Just do what feels good for a few hours...take out a few
cables...fondle them...blow out the dust bunnies...listen to
the Grateful Dead live at Winterland for inspiration. Drink
another beer...
Change a bunch of jumpers on the Mobo at random.
Leave shit scattered around on yer workbench and wander away.
Watch cartoons for another hour...
Come back and put it back together.
Holy Shit! Now it works.
Thats how I do it anyway.
FYI
HTH

Dunno why you geeks muck about with all that crap.

I take em out to the back 40, prop em against the side of the
gully and show them my Springfield 30-06.

BLINK
BLINK
OMG! I would never shoot a poor defenceless computer!

They always work after that.

I assume you miss...

Works good with the employees, wife and kids too.

Note to self: dont work for 'Ratz.

Never had need to actually fire the damn thing.

Interesting. So you say that pc's respond to threats of
annihilation? I've got a sledge hammer laying about...
Will it solve my booting problems?

Try steel toe caps.

That didnt help at all.

You didn't kick it hard enough.

Now it wont turn on at all.
You owe me a new computer.

You weren't supposed to kick the on/off switch; especially with steel toe
caps!

--
http://www.kustomkomputa.co.uk
- Personalised Desktop Computers

 

[§ńühw¤Łf]

Aratzio <a6ahlyv02@sneakemail.com> clouded the waters of pure thought with:

On Tue, 22 Apr 2008 08:53:35 -0700, in the land of alt.usenet.kooks,
§ńühw¤Łf <snuhwolf@netscape.net> got double secret probation for
writing:

On Mon, 21 Apr 2008 23:32:32 +0100
"Dr.Hal0nf1rŁ$" <femail@nospam.kustomkomputa.co.uk.invalid> wrote:

§ńühw¤Łf wrote:
On Sun, 20 Apr 2008 22:15:06 +0100
"Dr.Hal0nf1rŁ$" <femail@nospam.kustomkomputa.co.uk.invalid> wrote:

§ńühw¤Łf wrote:
On Sat, 19 Apr 2008 15:34:16 -0700
Aratzio <a6ahlyv02@sneakemail.com> wrote:

On Sat, 19 Apr 2008 16:09:53 -0500, in the land of
alt.usenet.kooks, snuhwolf@netscape.net (§ńühw¤Łf) got double
secret probation for writing:

Aratzio <a6ahlyv02@sneakemail.com> clouded the waters of pure
thought with:
On Sat, 19 Apr 2008 09:01:56 -0700, in the land of
alt.usenet.kooks, §ńühw¤Łf <snuhwolf@netscape.net> got double
secret probation for writing:

On Sat, 19 Apr 2008 13:35:53 +1000
"Kadaitcha Man" <nospam.nospam.nospam@gmail.com> wrote:

"Aratzio" <a6ahlyv02@sneakemail.com> wrote in message
news:9opi0456deigk7ihd4bq4mq3u9mar9tha3@4ax.com...
On Sat, 19 Apr 2008 13:26:03 +1000, in the land of
alt.usenet.kooks, "Kadaitcha Man"
nospam.nospam.nospam@gmail.com> got double secret probation
for writing:

"Butch Haynes" <butch@huntsville> wrote in message
news:zbmdnUfjYIjDTZXVnZ2dnUVZ_gWdnZ2d@comcast.com...
radiant_x@outgun.com> wrote in message
news:293e3140-e027-496c-89d8-27906e8991f7@t54g2000hsg.googlegroups.com...

I recently installed a DVD drive into my PC. (2 days ago.)
Since then, I get spontaneous power loss periodically -
sometimes seconds after booting, other times after hours of
operation. I've tried replacing the power supply, and I've
tried removing all my hardware (other than RAM), so I'm
thinking it must be motherboard related.

Unplug/replug all power and data connections. That way, the
errant loose one will be fixed and your problem will be
resolved.

BWAHAHAHAHAHAHAHAHAHAHAHAHA!

Tech support by feng shui.

"I've tried removing all my hardware(other than RAM)"

Do none of them understand what that entails?


None of them understand anything.

I go toetally on into-ition.
Just do what feels good for a few hours...take out a few
cables...fondle them...blow out the dust bunnies...listen to the
Grateful Dead live at Winterland for inspiration. Drink another
beer...
Change a bunch of jumpers on the Mobo at random.
Leave shit scattered around on yer workbench and wander away.
Watch cartoons for another hour...
Come back and put it back together.
Holy Shit! Now it works.
Thats how I do it anyway.
FYI
HTH

Dunno why you geeks muck about with all that crap.

I take em out to the back 40, prop em against the side of the
gully and show them my Springfield 30-06.

BLINK
BLINK
OMG! I would never shoot a poor defenceless computer!

They always work after that.

I assume you miss...

Works good with the employees, wife and kids too.

Note to self: dont work for 'Ratz.

Never had need to actually fire the damn thing.

Interesting. So you say that pc's respond to threats of
annihilation? I've got a sledge hammer laying about...
Will it solve my booting problems?

Try steel toe caps.

That didnt help at all.

You didn't kick it hard enough.

Now it wont turn on at all.
You owe me a new computer.

Ask Kman.

Kman bestoweth upon the unwashed masses the new computers?

ALL HALE KMAN FOR HE HACE MUCH GRATENES!!!1111!!!!!

--
www.alternet.org

 

[§ńühw¤Łf]

Aratzio <a6ahlyv02@sneakemail.com> clouded the waters of pure thought with:

On Tue, 22 Apr 2008 08:53:35 -0700, in the land of alt.usenet.kooks,
§ńühw¤Łf <snuhwolf@netscape.net> got double secret probation for
writing:

On Mon, 21 Apr 2008 23:32:32 +0100
"Dr.Hal0nf1rŁ$" <femail@nospam.kustomkomputa.co.uk.invalid> wrote:

§ńühw¤Łf wrote:
On Sun, 20 Apr 2008 22:15:06 +0100
"Dr.Hal0nf1rŁ$" <femail@nospam.kustomkomputa.co.uk.invalid> wrote:

§ńühw¤Łf wrote:
On Sat, 19 Apr 2008 15:34:16 -0700
Aratzio <a6ahlyv02@sneakemail.com> wrote:

On Sat, 19 Apr 2008 16:09:53 -0500, in the land of
alt.usenet.kooks, snuhwolf@netscape.net (§ńühw¤Łf) got double
secret probation for writing:

Aratzio <a6ahlyv02@sneakemail.com> clouded the waters of pure
thought with:
On Sat, 19 Apr 2008 09:01:56 -0700, in the land of
alt.usenet.kooks, §ńühw¤Łf <snuhwolf@netscape.net> got double
secret probation for writing:

On Sat, 19 Apr 2008 13:35:53 +1000
"Kadaitcha Man" <nospam.nospam.nospam@gmail.com> wrote:

"Aratzio" <a6ahlyv02@sneakemail.com> wrote in message
news:9opi0456deigk7ihd4bq4mq3u9mar9tha3@4ax.com...
On Sat, 19 Apr 2008 13:26:03 +1000, in the land of
alt.usenet.kooks, "Kadaitcha Man"
nospam.nospam.nospam@gmail.com> got double secret probation
for writing:

"Butch Haynes" <butch@huntsville> wrote in message
news:zbmdnUfjYIjDTZXVnZ2dnUVZ_gWdnZ2d@comcast.com...
radiant_x@outgun.com> wrote in message
news:293e3140-e027-496c-89d8-27906e8991f7@t54g2000hsg.googlegroups.com...

I recently installed a DVD drive into my PC. (2 days ago.)
Since then, I get spontaneous power loss periodically -
sometimes seconds after booting, other times after hours of
operation. I've tried replacing the power supply, and I've
tried removing all my hardware (other than RAM), so I'm
thinking it must be motherboard related.

Unplug/replug all power and data connections. That way, the
errant loose one will be fixed and your problem will be
resolved.

BWAHAHAHAHAHAHAHAHAHAHAHAHA!

Tech support by feng shui.

"I've tried removing all my hardware(other than RAM)"

Do none of them understand what that entails?


None of them understand anything.

I go toetally on into-ition.
Just do what feels good for a few hours...take out a few
cables...fondle them...blow out the dust bunnies...listen to the
Grateful Dead live at Winterland for inspiration. Drink another
beer...
Change a bunch of jumpers on the Mobo at random.
Leave shit scattered around on yer workbench and wander away.
Watch cartoons for another hour...
Come back and put it back together.
Holy Shit! Now it works.
Thats how I do it anyway.
FYI
HTH

Dunno why you geeks muck about with all that crap.

I take em out to the back 40, prop em against the side of the
gully and show them my Springfield 30-06.

BLINK
BLINK
OMG! I would never shoot a poor defenceless computer!

They always work after that.

I assume you miss...

Works good with the employees, wife and kids too.

Note to self: dont work for 'Ratz.

Never had need to actually fire the damn thing.

Interesting. So you say that pc's respond to threats of
annihilation? I've got a sledge hammer laying about...
Will it solve my booting problems?

Try steel toe caps.

That didnt help at all.

You didn't kick it hard enough.

Now it wont turn on at all.
You owe me a new computer.

Ask Kman.

Kman bestoweth upon the unwashed masses the new computers?

ALL HALE KMAN FOR HE HACE MUCH GRATENES!!!1111!!!!!

--
www.alternet.org

 

[GregS]

In article <300bf4d8-6b25-4fee-9536-1170843ae47d@e67g2000hsa.googlegroups.com>, EADGBE <hwbosshoss@comcast.net> wrote:

STOP THE PRESSES!

THE AMPLIFIER PROBLEM HAS BEEN *SOLVED* !!!!!!!!!!!!!!!!!!

SEE MY POST REGARDING THIS!!!!!!!!

MANY, MANY THANKS TO EVERYONE WHO OFFERED HELP, TIPS, AND
SUGGESTIONS!!!!!!!!!!!!!!!!!!!!!!!

Maybe we can improve the design ?

greg

 

[GregS]

In article <300bf4d8-6b25-4fee-9536-1170843ae47d@e67g2000hsa.googlegroups.com>, EADGBE <hwbosshoss@comcast.net> wrote:

STOP THE PRESSES!

THE AMPLIFIER PROBLEM HAS BEEN *SOLVED* !!!!!!!!!!!!!!!!!!

SEE MY POST REGARDING THIS!!!!!!!!

MANY, MANY THANKS TO EVERYONE WHO OFFERED HELP, TIPS, AND
SUGGESTIONS!!!!!!!!!!!!!!!!!!!!!!!

Maybe we can improve the design ?

greg

 

[Arfa Daily]

"EADGBE" <hwbosshoss@comcast.net> wrote in message
news:4ca08117-23b7-48de-b7ef-733200c162d0@x41g2000hsb.googlegroups.com...

Good News!

This headphone amplifier has been REPAIRED and is now working
perfectly.

Here's what happened:

I have been taking parallel measurements between the "good" and "bad"
channels since the beginning.

I took voltage measurements, resistance measurements, tested ALL
capacitors, and tested ALL transistors.

But someone in my original thread (I can't remember who offhand --
sorry) did mention checking the circuit board traces.

"No need," I thought. "The circuit board and all solder joints look
fine to me."

But in a fit of desperation, I nonetheless decided to whip out a
tester I hadn't used yet: my magnifying glass.

That's when I found it -- a *microscopic* crack in the trace between
the emitter of Q208 and its adjoining 3.3 ohm resistor. The crack was
so incredibly tiny that I easily overlooked it--repeatedly.

I took one of my jumper leads and clipped one end of it to Q208's
emitter and the other end of it to the 3.3 ohm resistor.

I then took voltage measurements. EVERYTHING WAS NOW ON SPEC:

Q205's collector now measures +7.09V, and Q206 now has the following
measurements:
B: +6.51V
C: +7.08V
E: +5.84V

I was able to bridge the crack with a well-placed solder trail, and
the headphone amp now sounds great.

A BIG "THANK YOU" TO EVERYONE WHO HELPED ME OUT! I OWE YOU BIG TIME.

Well done on finding the problem - a deserved result. However, can I make
one suggestion ? Don't rely on just solder to bridge the crack, as it *will*
cause trouble again. The crack causes the solder to form a crystalline
'wall' above it, inside the joint, as it resolidifies. Any cracks, however
tiny, *must* be bridged by at least one strand from some hookup wire. If you
can get a good joint to a solder point either side of the crack, then do
that. If that is not practical, scrape back the solder resist on the
tracking either side of the crack, and then bury your strand of wire in the
solder bridge. As I know that you do these repairs to further your
knowledge, that is a professional 'reliable repair' tip that you should add
to your knowledge base.

Arfa