[Tom]

Hey guys,

Model: Toshiba TP61H60 rear projection TV
Age: approximately 6 years

I just replaced both STK392-110 ICs. No change in the convergence
problem. I can't adjust the convergence any better than it is now.

I took some pictures of the screen image:
http://www.arcadeguy.net/Toshiba1.jpg
http://www.arcadeguy.net/Toshiba2.jpg
http://www.arcadeguy.net/Toshiba3.jpg

What should I look at replacing or adjusting next??

Thank you,
Tom

 

[BWL]

Probably one or more output resistors are open; usually small value 1 watt...

 

[Tom]

BWL stated:

Probably one or more output resistors are open; usually small value 1
watt...

Hmmm...and those resistors are located where? No problem replacing them,
just knowing which ones. I am working without schematics or manual.

I was going to replace capacitors in the area of the STK's as my next step
since I didn't even consider resistors going bad.

Thank you,
Tom

 

[Art]

There are numerous resistors in the same physical area as the STK devices.
Check each one and compare those on one circuit withthose in another. If in
doubt you may want to have a professional have a go at the tele. Or at least
buy the service manual or a SAMS Photofact.

 

[Robotron Tom]

Art stated:

There are numerous resistors in the same physical area as the STK
devices. Check each one and compare those on one circuit withthose in
another. If in doubt you may want to have a professional have a go at
the tele. Or at least buy the service manual or a SAMS Photofact.

Great idea...I'll start on that tomorrow. Am I going to be able to check
these resistors in circuit? Do you know if this set is capable of
generating test patterns? I went into service mode but couldn't get a
pattern to come on.

I did find the service manual online for $20, so that is going to happen.

--
Robotron Tom *remove nospam to email*
See the Flashback Arcade at: http:// www.arcadeguy.net

Standing for right when it is unpopular is a true test of moral
character.
-M. Smith

 

[BubbaJim]

Art stated:


Great idea...I'll start on that tomorrow. Am I going to be able to
check these resistors in circuit? Do you know if this set is capable
of generating test patterns? I went into service mode but couldn't get
a pattern to come on.

I did find the service manual online for $20, so that is going to
happen.

Will the affected color(s) convergence adjust vertically and
horizontally? If they do , resistors probably are NOT the problem, you
could be looking at a bad yoke (only saw it once) or a bad DCU. Pull the
affected yoke and look for evidence of arcing/burning.
bubbajim

 

[Art]

Agreed, Bubba: Toshiba has encountered a fair number of defective yokes,
that can be easily diagnosed by doing a DC resistance or even ringing them.
The DCU is another possibility but almost as rare as the yokes.

 

[John Del]

Subject: Re: Convergence Problem

From: BubbaJim [email protected]
Date: 12/10/04 3:54 AM Eastern
you
could be looking at a bad yoke (only saw it once) or a bad DCU. Pull the
affected yoke and look for evidence of arcing/burning.
bubbajim

I've changed plenty of Toshiba yokes. The ones that show physical damage
usually cause shutdown, so ringing or scoping the signal is the best option.
I've also seen bad DCUs and corrupted eeproms in these models.

John Del
Wolcott, CT

"I'm just trying to get into heaven, I'm not running for Jesus!"
Homer Simpson

(remove S for email reply)

 

[Tom]

BubbaJim stated:

Will the affected color(s) convergence adjust vertically and
horizontally? If they do , resistors probably are NOT the problem, you
could be looking at a bad yoke (only saw it once) or a bad DCU. Pull
the affected yoke and look for evidence of arcing/burning.
bubbajim

Yes, I am able to make both adjustments on the blue, which is the problem
gun. Now, what is a DCU? I haven't heard mention of this acronym yet.

Thank you,
Tom

 

[Tom]

Art stated:

Agreed, Bubba: Toshiba has encountered a fair number of defective
yokes, that can be easily diagnosed by doing a DC resistance or even
ringing them. The DCU is another possibility but almost as rare as the
yokes.

Okay, what the heck is 'ringing'? That is definately a new one on me.

Thank you,
Tom

 

[Robotron Tom]

John Del stated:

I've changed plenty of Toshiba yokes. The ones that show physical
damage usually cause shutdown, so ringing or scoping the signal is the
best option. I've also seen bad DCUs and corrupted eeproms in these
models.

John Del

Sorry, I just remembered that after this blue skew came about, sometimes
the whole picture would do a kind of wide angle jump. It made the picture
look a bit wider and it would only happen for a few seconds then go back
to a normal size image. This affected all colors.

Does that indicate another problem or could it be a part of this problem?

Thank you,
Tom

 

[James Sweet]

Will the affected color(s) convergence adjust vertically and
horizontally? If they do , resistors probably are NOT the problem, you
could be looking at a bad yoke (only saw it once) or a bad DCU. Pull the
affected yoke and look for evidence of arcing/burning.
bubbajim

Or just swap the plugs with one of the other yokes and see if the problem
stays with the same color.

 

[James Sweet]

Art stated:


Okay, what the heck is 'ringing'? That is definately a new one on me.

Using a flyback "ring tester" essentially injects a signal and counts the
number of times an inductor resonates. A shorted turn will kill this
resonation very quickly.

Should be ok with a DC ohms test though.

 

[Tom]

James Sweet stated so wisely:

Or just swap the plugs with one of the other yokes and see if the
problem stays with the same color.

HEY...great idea!

Now...I read somewhere that these projectors don't hold a charge like a
CRT. Will I need to discharge it before removing??

Thank you,
Tom

"That man is richest whose pleasures are cheapest."
-Henry Thoreau

 

[Tom]

James Sweet stated so wisely:

Using a flyback "ring tester" essentially injects a signal and counts the
number of times an inductor resonates. A shorted turn will kill this
resonation very quickly.

Ahhh...I don't have that kind of equipment, as you've probably guessed.

Should be ok with a DC ohms test though.

And what Ohm range should a good flyback be?

QUESTION: Is there a chance that this <gun> might be low on fluid?
I apologize for not knowing the proper term for this component. Could you
please correct me on the nomenclature?

I do have a scope(although not very versed on it's usage), is there
something I could check that will narrow this down quickly with it?

Thank you,
Tom

"That man is richest whose pleasures are cheapest."
-Henry Thoreau

 

[James Sweet]

James Sweet stated so wisely:


HEY...great idea!

Now...I read somewhere that these projectors don't hold a charge like a
CRT. Will I need to discharge it before removing??

They're CRT's like any other and can hold a charge, but you're just dealing
with the yokes, not the HV, don't worry about it. You're more likely to
shock yourself trying to discharge the CRT's than if you just leave that
part alone.

 

[Tom]

James Sweet stated so wisely:

They're CRT's like any other and can hold a charge, but you're just
dealing with the yokes, not the HV, don't worry about it. You're more
likely to shock yourself trying to discharge the CRT's than if you
just leave that part alone.

AAaahhh...now I get it. I misunderstood you the first time. That is a
simple check. I'll check it and get back here to let you know.

Thank you,
Tom

"That man is richest whose pleasures are cheapest."
-Henry Thoreau

 

[James Sweet]

James Sweet stated so wisely:


Ahhh...I don't have that kind of equipment, as you've probably guessed.

If you ever start repairing more TV's and stuff you can pick one up for
under $50, they're pretty simple instruments.

And what Ohm range should a good flyback be?

Flyback? I thought we were talking about yokes? You generally can't test a
flyback with an ohm meter, good ones are all over the map.

QUESTION: Is there a chance that this <gun> might be low on fluid?
I apologize for not knowing the proper term for this component. Could you
please correct me on the nomenclature?

The CRT could be low on coolant, but that'd be easy to check by just peering
down the lense with a flashlight, if it's low it should be obvious.

I do have a scope(although not very versed on it's usage), is there
something I could check that will narrow this down quickly with it?

Not really, a scope is only useful if you know what to expect so you can
compare it to what you see.

 

[Tom]

James Sweet stated so wisely:

If you ever start repairing more TV's and stuff you can pick one up
for under $50, they're pretty simple instruments.

This is a project and money saver for my retired dad, so not likely.

Flyback? I thought we were talking about yokes? You generally can't
test a flyback with an ohm meter, good ones are all over the map.

Yes, my mistake.

The CRT could be low on coolant, but that'd be easy to check by just
peering down the lense with a flashlight, if it's low it should be
obvious.

Okay, the CRT doesn't appear to be low on coolant. I did look inside
through the lens with the set on. Knowing that the skew was on the left
side of the screen, I looked into the lens of the blue CRT and on the
right side and I could see the skew very well. (It looked as if a sheet
of clear (or blue) plastic was in there and it had an upward curve in
that area as if it had been heat warped. I realize there isn't a sheet of
plastic in there, that's just what it looked like.

I replace the front screen and tried the user convergence adjustment
again and the blue + that is usually over the white(red/green/blue) +, is
way over at the left edge so that I can only see the right tip when I
move it to the right as far as it will go. I can see that tip move
up/down/left/right, although if I move it left, the tip disappears.

So...anymore ideas or information you need to help diagnose this?

If the CRT is bad, what will a replacement cost me?

Thank you,
Tom

"That man is richest whose pleasures are cheapest."
-Henry Thoreau

 

[James Sweet]

If the CRT is bad, what will a replacement cost me?

The CRT is fine, it's lighting up, so at any rate it's not the cause of this
problem. If the yoke is bad, who knows, you might be able to repair it or
find a good used one. The yoke could be fine though.