RCA TV - Help needed with overscan correction

[Karyudo]

I've got an RCA F27689, built in 2001. Not the world's best 27" TV,
but decent enough for me right now.

I'm a bit of a tweaker, so I've already found out how to get into the
service mode of my TV. I'm also a fairly cautious type, so I also
wrote down all the default values for my set before attempting to mess
with anything. I've also read some horror stories that suggest if
you're going to be fiddling with things in the service menu, you'd
best be prepared for the consequences of messing something up
permanently (or at least enough to require a visit to a service
technician). You may consider me a fool, but the potential benefits of
tweaking make that a risk I'm willing to take.

Using a Digital Video Essentials test pattern as a guide, I can see
that some parameters make visible changes: I've found vertical
position, vertical size, and horizontal position, for example.

However, the one thing I really want to change -- horizontal size, to
correct for what I feel is an awful lot of horizontal overscan -- has
thus far eluded me. I'm beginning to think maybe it can't be adjusted
at all (!), but I don't really want to believe that just yet. I'm
hoping maybe there's another password to set, and further parameters
to adjust. Or that one of the parameters I don't see doing anything
can be made to do something, somehow. I don't know -- I'm grasping at
theoretical straws here.

Could somebody with a little (or a lot) more experience than I've got
give me a couple of pointers? Thanks kindly...

[crossposted to sci.electronics.repair and rec.video]

 

[Karyudo]

I've got an RCA F27689, built in 2001.

Quick update: the chassis number is CTC197A8.

[crossposted to sci.electronics.repair and rec.video]

 

[JANA]

I don't know your set in detail, but I have some suggestions.

I would think it would be a good idea for you to invest in the service
manual. They should give instructions for the complete set-up of your set.
There will be test equipment necessary to do all of the set-ups to any great
detail. What you want to do, is mainly visually referenced, using a test
pattern on the screen.

In some models of sets, they use some resistors with jumpers that are
soldered to them to set the width. Some sets have a connector that is
selectable for the width. Another way of doing this, is that there may be a
pot or width coil on the main chassis in the horizontal output area.

--

JANA
_____


I've got an RCA F27689, built in 2001. Not the world's best 27" TV,
but decent enough for me right now.

I'm a bit of a tweaker, so I've already found out how to get into the
service mode of my TV. I'm also a fairly cautious type, so I also
wrote down all the default values for my set before attempting to mess
with anything. I've also read some horror stories that suggest if
you're going to be fiddling with things in the service menu, you'd
best be prepared for the consequences of messing something up
permanently (or at least enough to require a visit to a service
technician). You may consider me a fool, but the potential benefits of
tweaking make that a risk I'm willing to take.

Using a Digital Video Essentials test pattern as a guide, I can see
that some parameters make visible changes: I've found vertical
position, vertical size, and horizontal position, for example.

However, the one thing I really want to change -- horizontal size, to
correct for what I feel is an awful lot of horizontal overscan -- has
thus far eluded me. I'm beginning to think maybe it can't be adjusted
at all (!), but I don't really want to believe that just yet. I'm
hoping maybe there's another password to set, and further parameters
to adjust. Or that one of the parameters I don't see doing anything
can be made to do something, somehow. I don't know -- I'm grasping at
theoretical straws here.

Could somebody with a little (or a lot) more experience than I've got
give me a couple of pointers? Thanks kindly...

[crossposted to sci.electronics.repair and rec.video]

 

[kip]

If it needs to be adjusted you will need Chipper Checker
and if its really got overscan then the set needs to be repaired.

kip

 

[Leonard Caillouet]

Kip, why do you need the Chipper Check to make adjustments on this set?

I don't recall any horizontal size adjustment on the 197 chassis. This is
not uncommon on 27" televisions.

Leonard

If it needs to be adjusted you will need Chipper Checker
and if its really got overscan then the set needs to be repaired.

kip

I've got an RCA F27689, built in 2001. Not the world's best 27" TV,
but decent enough for me right now.

I'm a bit of a tweaker, so I've already found out how to get into the
service mode of my TV. I'm also a fairly cautious type, so I also
wrote down all the default values for my set before attempting to mess
with anything. I've also read some horror stories that suggest if
you're going to be fiddling with things in the service menu, you'd
best be prepared for the consequences of messing something up
permanently (or at least enough to require a visit to a service
technician). You may consider me a fool, but the potential benefits of
tweaking make that a risk I'm willing to take.

Using a Digital Video Essentials test pattern as a guide, I can see
that some parameters make visible changes: I've found vertical
position, vertical size, and horizontal position, for example.

However, the one thing I really want to change -- horizontal size, to
correct for what I feel is an awful lot of horizontal overscan -- has
thus far eluded me. I'm beginning to think maybe it can't be adjusted
at all (!), but I don't really want to believe that just yet. I'm
hoping maybe there's another password to set, and further parameters
to adjust. Or that one of the parameters I don't see doing anything
can be made to do something, somehow. I don't know -- I'm grasping at
theoretical straws here.

Could somebody with a little (or a lot) more experience than I've got
give me a couple of pointers? Thanks kindly...

[crossposted to sci.electronics.repair and rec.video]

 

[RonKZ650]

I don't have the exact CTC197A8 scematic, but other 27" CTC197 use
parameter 5 as horiz size adjustment in the service menu.

 

[Leonard Caillouet]

This is correct. The set does have horizontal size adjustment, parameter 5.

Leonard

 

[kip]

Yes
But did the set develop a fault that now gives excessive
scan or not, or does he want to reduce what is normal
on those TV,s.
Has the TV always been like it ???
Gotta tell us more info.

kip

 

[Karyudo]

I've done a bit more searching, based on the fact that I now know the
chassis number can also tell me a lot!

I've found the complete set of service codes for the CTC197:

Parameter # Description:
0 Security Pass
1 Error code
2 Error code
3 Error code
4 Horiz Phase
5 EW DC (Horiz size)
6 Pin Cush Amplitude
7 Pincush Tilt
8 Pin Top Corner Correction
9 Pin Bottom Corner Correction
10 Vert Centering
11 Vert Size
12 Vert Countdown Mode
13 Red Bias
14 Green Bias
15 Blue Bias
16 Red Drive
17 Green Drive
18 Blue Drive
19 Gemstar OSD Horizontal
20 Gemstar OSD Vertical
21 Gemstar Horiz. PIP
22 Gemstar Vert. PIP
23 Gemstar PIP Window Vertical

....and sure enough, this matches what I've been able to figure out on
my own thus far.

However, I also found a forum conversation that goes thusly:

Q: "I've located the proper parameter in service mode to adjust the
horizontal width of my RCA TV, however, it doesn't affect the display
when altered. The vertical sizing and centering parameters do work. I
was using P5 which was indicated in the Service Manual for a CTC197
chassis. Any thoughts?"

A: "Your set may not have the option to adjust the pin or horizontal
size depending on the size of the TV and feature level it was built
with. I can guarantee that if it is smaller than a 27" it does not
have any horizontal adjustments available."

Sadly, this also matches what I've been able to figure out. So I guess
if the horizontal size can be changed, it won't be through the service
menu. Damn.

But did the set develop a fault that now gives excessive
scan or not, or does he want to reduce what is normal
on those TVs. Has the TV always been like [that]?

Yeah, it's always been like that, and no, there's no fault per se. But
I still feel that there's too much stuff being cut off. Titles on some
movies or TV shows, for example, are butted right up against the edge
of the screen -- and sometimes they're even cut off a bit. So I'm
guessing I'm missing part of the 'TV title safe' area?

I can change the horizontal position adjustment (P:04) from one
extreme to another, and still not see the very edge of the picture on
either side. I mean, this is *acceptable*, but it's not *optimal*.
It's disappointing to learn that this is likely not an easy tweak to
make. But I'm a persistent geek if nothing else, so I'd still be
interested to hear what I might have to do "under the hood" to have a
shot at reducing the overscan on my set.

Any further ideas?? (Thanks, everyone!)

 

[Karyudo]

I would [...] invest in the service manual.

Sounds good. Where can I find one? I've heard something like Thomson
something-or-other, but that's not quite enough detail. Any more
hints?

In some models of sets, they use some resistors with jumpers that are
soldered to them to set the width. Some sets have a connector that is
selectable for the width. Another way of doing this, is that there may be a
pot or width coil on the main chassis in the horizontal output area.

All three of these are strategies I would pursue. Changing out a
jumper -- or even a resistor -- is within my cautious capabilities, I
think. If I were to take the back of the set off, what would I be
looking for, and where would I look for it? Any hints on what sort of
label (e.g. printed on the PCB?) I'd see? (Oh, and don't worry: I'm
not going to touch anything metal until it's been off for the better
part of a day, lest I fry myself or something else).

Thanks for your help!

 

[kip]

Ok!
Its time for you to take the TV to a service shop before you kill the set.
definitely this is way above you.
kip

I would [...] invest in the service manual.

Sounds good. Where can I find one? I've heard something like Thomson
something-or-other, but that's not quite enough detail. Any more
hints?

In some models of sets, they use some resistors with jumpers that are
soldered to them to set the width. Some sets have a connector that is
selectable for the width. Another way of doing this, is that there may be
a
pot or width coil on the main chassis in the horizontal output area.

All three of these are strategies I would pursue. Changing out a
jumper -- or even a resistor -- is within my cautious capabilities, I
think. If I were to take the back of the set off, what would I be
looking for, and where would I look for it? Any hints on what sort of
label (e.g. printed on the PCB?) I'd see? (Oh, and don't worry: I'm
not going to touch anything metal until it's been off for the better
part of a day, lest I fry myself or something else).

Thanks for your help!

 

[Leonard Caillouet]

Do not try to alter the horizontal width in hardware. You obviously do not
understand the operation or design of the circuits enough to do so without a
high probability of damage to the set.

Leonard

I would [...] invest in the service manual.

Sounds good. Where can I find one? I've heard something like Thomson
something-or-other, but that's not quite enough detail. Any more
hints?

In some models of sets, they use some resistors with jumpers that are
soldered to them to set the width. Some sets have a connector that is
selectable for the width. Another way of doing this, is that there may be a
pot or width coil on the main chassis in the horizontal output area.

All three of these are strategies I would pursue. Changing out a
jumper -- or even a resistor -- is within my cautious capabilities, I
think. If I were to take the back of the set off, what would I be
looking for, and where would I look for it? Any hints on what sort of
label (e.g. printed on the PCB?) I'd see? (Oh, and don't worry: I'm
not going to touch anything metal until it's been off for the better
part of a day, lest I fry myself or something else).

Thanks for your help!

 

[Karyudo]

You obviously do not

understand the operation or design of the circuits enough to do so without a
high probability of damage to the set.

You misunderestimate me. *Of course* I don't understand the circuits
enough -- yet. I'm not going to do a damn thing until I do, and until
there's a much lower probability of damage to the set (preferably
hovering around 'nil').

What I really need now is not dire warnings, but more information
about either the circuits themselves, or where to find the
information. I know service manuals exist; I'd like to know how to get
one. I'm educated, bright (enough), and cautious. I'm not going to
mess anything up, because I won't touch anything until I'm pretty
positive I'm touching the right thing.

One observation: TVs suck. Computer monitors (and I mean *all of
them*) have allowed the end user to adjust just about every damn thing
-- including horizontal width, of course -- for at least about a dozen
years. This is not rocket science, it's just crappy engineering. The
fact that I've even got to consider some dangerous hardware mod just
to get the whole picture on the screen is ludicrous.

 

[Art]

YES, go out and by an APEX TV!!

I've done a bit more searching, based on the fact that I now know the
chassis number can also tell me a lot!

I've found the complete set of service codes for the CTC197:

Parameter # Description:
0 Security Pass
1 Error code
2 Error code
3 Error code
4 Horiz Phase
5 EW DC (Horiz size)
6 Pin Cush Amplitude
7 Pincush Tilt
8 Pin Top Corner Correction
9 Pin Bottom Corner Correction
10 Vert Centering
11 Vert Size
12 Vert Countdown Mode
13 Red Bias
14 Green Bias
15 Blue Bias
16 Red Drive
17 Green Drive
18 Blue Drive
19 Gemstar OSD Horizontal
20 Gemstar OSD Vertical
21 Gemstar Horiz. PIP
22 Gemstar Vert. PIP
23 Gemstar PIP Window Vertical

...and sure enough, this matches what I've been able to figure out on
my own thus far.

However, I also found a forum conversation that goes thusly:

Q: "I've located the proper parameter in service mode to adjust the
horizontal width of my RCA TV, however, it doesn't affect the display
when altered. The vertical sizing and centering parameters do work. I
was using P5 which was indicated in the Service Manual for a CTC197
chassis. Any thoughts?"

A: "Your set may not have the option to adjust the pin or horizontal
size depending on the size of the TV and feature level it was built
with. I can guarantee that if it is smaller than a 27" it does not
have any horizontal adjustments available."

Sadly, this also matches what I've been able to figure out. So I guess
if the horizontal size can be changed, it won't be through the service
menu. Damn.

But did the set develop a fault that now gives excessive
scan or not, or does he want to reduce what is normal
on those TVs. Has the TV always been like [that]?

Yeah, it's always been like that, and no, there's no fault per se. But
I still feel that there's too much stuff being cut off. Titles on some
movies or TV shows, for example, are butted right up against the edge
of the screen -- and sometimes they're even cut off a bit. So I'm
guessing I'm missing part of the 'TV title safe' area?

I can change the horizontal position adjustment (P:04) from one
extreme to another, and still not see the very edge of the picture on
either side. I mean, this is *acceptable*, but it's not *optimal*.
It's disappointing to learn that this is likely not an easy tweak to
make. But I'm a persistent geek if nothing else, so I'd still be
interested to hear what I might have to do "under the hood" to have a
shot at reducing the overscan on my set.

Any further ideas?? (Thanks, everyone!)

 

[Leonard Caillouet]

How much overscan are you talking about? The set is designed with between 5
& 10 percent, and closer to 10 is not uncommon.

You can get the manuals from Thomson Consumer Electronics or their
distributors, such as Tritronics. Be sure to get the training manuals as
well as the service manual.

Leonard

 

[Karyudo]

How much overscan are you talking about? The set is designed with between 5
& 10 percent, and closer to 10 is not uncommon.

I'm not exactly sure how much it is. Yet. I have yet to put up the DVE
screen that shows how much overscan I've got. I'd guess I'm at the
high end of normal. It's not *terrible*, but I think it could be a
fair bit better. I'm sure overscan hides a multitude of evils, but I'd
like to see for myself. I want to be more hands-on than RCA's letting
me be...

You can get the manuals from Thomson Consumer Electronics or their
distributors, such as Tritronics. Be sure to get the training manuals as
well as the service manual.

Thanks, Leonard!

 

[Karyudo]

YES, go out and by an APEX TV!!

Dude, if I had money enough to go out and buy a new TV, I probably
would. Actually, no, I wouldn't: I have a TV that works just fine. I
just want it to work a little *better* than 'fine'. Part of the fun is
to figure out what to tweak and how to tweak it.

And if I did decide to buy a new TV, I doubt I'd start with Apex, even
though I'm in that minority that has had excellent results and a long
-- continuing -- life out of his AD-600A.

What's so hot about the Apex TVs, may I ask?

 

[Art]

Flippin won't take the Tompson item to a pro for service so might as well
buy a cheapo you can toss rather than continue this rant, Eh Dude??

 

[Leonard Caillouet]

What is wrong with the guy wanting to tweak on his set?

Leonard

 

[Andy Cuffe]

I've got an RCA F27689, built in 2001. Not the world's best 27" TV,
but decent enough for me right now.

However, the one thing I really want to change -- horizontal size, to
correct for what I feel is an awful lot of horizontal overscan -- has
thus far eluded me. I'm beginning to think maybe it can't be adjusted
at all (!), but I don't really want to believe that just yet. I'm
hoping maybe there's another password to set, and further parameters
to adjust. Or that one of the parameters I don't see doing anything
can be made to do something, somehow. I don't know -- I'm grasping at
theoretical straws here.

The horizontal size can't be adjusted on most RCA 27" TVs. You'll
have to live with the horizontal overs canning. You probably could
modify it, but it would be easier and cheaper in the long run to
replace it with a better set. For example, all Sony 27" TVs from the
early 90's on have a horizontal size adjustment.
Andy Cuffe

[email protected] <-- Use this address until 12/31/2005

[email protected] <-- Use this address after 12/31/2005