Zenith sc2593l horizontal size hint?

[Michael Gardner]

Everything works on this 1986 Zenith TV, except the horizontal size is
way too big - losing about 25% of picture on one side (vertical probably
a bit too big too). I can't visually find anything labeled
appropriately. Is this likely to be a pot/coil on the main board or on
the back of the tube or related to B+ or something?
tnx
mgg

 

[Sofie]

mgg:
Certainly, as you suggested, you should check the regulated B+ and verify
that the B+ regulation circuitry is operating properly.
No, it is probably not a pot or a coil, and even if you made such
adjustments to compensate for faulty circuitry ..... this is not a very good
idea..... something is faulty, causing the symptoms you reported and it
must be fixed.... if you try to "adjust" the problem to make the symptoms
go away, more expensive damage to more components can occur. Get it fixed
properly right away.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
----------------------------


"Michael Gardner" <mgg@prairienet.org> wrote in message
news:mgg-3CD7A5.21411610102003@wildfire.prairienet.org...

Everything works on this 1986 Zenith TV, except the horizontal size is
way too big - losing about 25% of picture on one side (vertical probably
a bit too big too). I can't visually find anything labeled
appropriately. Is this likely to be a pot/coil on the main board or on
the back of the tube or related to B+ or something?
tnx
mgg

 

[Michael Gardner]

In article <voevo64oc62o2b@corp.supernews.com>,
"Sofie" <sofie@olypen.com> wrote:

mgg:
Certainly, as you suggested, you should check the regulated B+ and verify
that the B+ regulation circuitry is operating properly.
No, it is probably not a pot or a coil, and even if you made such
adjustments to compensate for faulty circuitry ..... this is not a very good
idea..... something is faulty, causing the symptoms you reported and it
must be fixed.... if you try to "adjust" the problem to make the symptoms
go away, more expensive damage to more components can occur. Get it fixed
properly right away.

Always some smart mouth electronics tech who can't offer any real help,
except to tell you to "fix it right".

Lets review. It is a 1986 tv set. It isn't worth fixing right if
fixing right takes more than an hour or a few dollars. This tv set was
the main set and video game TV in a house full of teens for over twelve
years. That's something over 26,000 hours of operation. It was dumped
in the basement where it has sat unpowered for 5 years. I want the
space back and knew someone I could give it to. I learned to fix tv's
back int he 60's - as soon as I could see over the edge of my fathers
work bench. Many sets back then certainly had adjustments for size and
most anything else you'd want to tweak. I know newer sets often don't
have such adjustments - relying more on ICs and preset regulators - yet
this set has over 30 adjustments - few with any labels. While I'm quite
capable of (and have) tracing out circuit boards - I have far better
things to do with my time than repair tv's (especially without
schematics). Thus I've not done much of it, even on 86 models - so I was
asking for a bit of info that might save a TV for someone who doesn't
have one rather than being tossed into next weeks large trash pickup.

Is there someone who has worked on an old zenith recently that would
like to speak up?

Thanks
mgg

--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
----------------------------


"Michael Gardner" <mgg@prairienet.org> wrote in message
news:mgg-3CD7A5.21411610102003@wildfire.prairienet.org...
Everything works on this 1986 Zenith TV, except the horizontal size is
way too big - losing about 25% of picture on one side (vertical probably
a bit too big too). I can't visually find anything labeled
appropriately. Is this likely to be a pot/coil on the main board or on
the back of the tube or related to B+ or something?
tnx
mgg


--

Real Working Engineer

 

[Jason D.]

On Sat, 11 Oct 2003 14:50:15 -0500, Michael Gardner
<mgg@prairienet.org> wrote:

In article <voevo64oc62o2b@corp.supernews.com>,
"Sofie" <sofie@olypen.com> wrote:

mgg:
Certainly, as you suggested, you should check the regulated B+ and verify
that the B+ regulation circuitry is operating properly.
No, it is probably not a pot or a coil, and even if you made such
adjustments to compensate for faulty circuitry ..... this is not a very good
idea..... something is faulty, causing the symptoms you reported and it
must be fixed.... if you try to "adjust" the problem to make the symptoms
go away, more expensive damage to more components can occur. Get it fixed
properly right away.

Always some smart mouth electronics tech who can't offer any real help,
except to tell you to "fix it right".

Actually this is true. Double check this tv isn't simply too wide due
to faulty component in the horizontal section or has pincushion fault.
Looks like )( which is what pincushion circuit corrects it to straight
sides and forms a tuned horizontal circuit. With any of horizontal
circuits faulty, not just pincushion; horizontal circuit is out of
tune and can kill the horizontal transistor eventually and usually
snowball into many blown parts when horizontal transistor shorts.
That I can say for sure, seen this many, many times.

Both faulty horizontal circuit or pincushion failure can make picture
wide.

Ajustment is last thing to do after repair. Always.

Best to get the schematic info and check all the components are good,
check solder connections are good, zenith is famous for bad solder
joints & dried up electrolytic capacitors by find them with ESR meter
or replace key caps in that area.

Cheers,

Wizard

Lets review. It is a 1986 tv set. It isn't worth fixing right if

 

[David]

You want 'free' help on an old clunker of a tv set that you admit is too old
to spend any money on it. What makes you think any real technician would
have seen one of those old beasts in the last several years. Everyone has
the same attitude like you and simply trash bins the set, hence no one has
recently worked on one of those.

That set also was designed as a module level replacement with little real
component level troubleshooting ever performed. Given the age a good start
would be to pull out your capacitor ESR meter and start checking in critical
areas.

You are on the right track in starting with checking the main b+ voltage,
then the horizontal drive circuit and pincushion circuits would also need
checked. If you were to 'adjust' out the failure and it was due to high b+
or a detuned horizontal output stage, you would be asking for real trouble.

For someone with some basic electronics troubleshooting experience on a tv
set it should only take a matter of minutes to track down the general
circuit area causing the fault. At that point an experienced tech would be
able to decide if the set was worth going any farther.

There is always someone who thinks they know how to fix tv sets because they
use to swap parts and twiddle with things until they worked 40+ years ago.
There is a big difference between someone who was a parts swapper and a real
technician who actually knew what they were doing.

David


Michael Gardner <mgg@prairienet.org> wrote in message
news:mgg-1EC513.14501411102003@wildfire.prairienet.org...

In article <voevo64oc62o2b@corp.supernews.com>,
"Sofie" <sofie@olypen.com> wrote:

mgg:
Certainly, as you suggested, you should check the regulated B+ and
verify
that the B+ regulation circuitry is operating properly.
No, it is probably not a pot or a coil, and even if you made such
adjustments to compensate for faulty circuitry ..... this is not a very
good
idea..... something is faulty, causing the symptoms you reported and it
must be fixed.... if you try to "adjust" the problem to make the
symptoms
go away, more expensive damage to more components can occur. Get it
fixed
properly right away.

Always some smart mouth electronics tech who can't offer any real help,
except to tell you to "fix it right".

Lets review. It is a 1986 tv set. It isn't worth fixing right if
fixing right takes more than an hour or a few dollars. This tv set was
the main set and video game TV in a house full of teens for over twelve
years. That's something over 26,000 hours of operation. It was dumped
in the basement where it has sat unpowered for 5 years. I want the
space back and knew someone I could give it to. I learned to fix tv's
back int he 60's - as soon as I could see over the edge of my fathers
work bench. Many sets back then certainly had adjustments for size and
most anything else you'd want to tweak. I know newer sets often don't
have such adjustments - relying more on ICs and preset regulators - yet
this set has over 30 adjustments - few with any labels. While I'm quite
capable of (and have) tracing out circuit boards - I have far better
things to do with my time than repair tv's (especially without
schematics). Thus I've not done much of it, even on 86 models - so I was
asking for a bit of info that might save a TV for someone who doesn't
have one rather than being tossed into next weeks large trash pickup.

Is there someone who has worked on an old zenith recently that would
like to speak up?

Thanks
mgg

--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
----------------------------


"Michael Gardner" <mgg@prairienet.org> wrote in message
news:mgg-3CD7A5.21411610102003@wildfire.prairienet.org...
Everything works on this 1986 Zenith TV, except the horizontal size is
way too big - losing about 25% of picture on one side (vertical
probably
a bit too big too). I can't visually find anything labeled
appropriately. Is this likely to be a pot/coil on the main board or
on
the back of the tube or related to B+ or something?
tnx
mgg


--
Real Working Engineer

 

[Sofie]

snipped:

"Michael Gardner" <mgg@prairienet.org> wrote in message
news:mgg-3CD7A5.21411610102003@wildfire.prairienet.org...
Everything works on this 1986 Zenith TV, except the horizontal size is
way too big - losing about 25% of picture on one side (vertical
probably
a bit too big too). I can't visually find anything labeled
appropriately. Is this likely to be a pot/coil on the main board or
on
the back of the tube or related to B+ or something?
tnx
mgg
----------------------------------------

mgg:
Certainly, as you suggested, you should check the regulated B+ and
verify
that the B+ regulation circuitry is operating properly.
No, it is probably not a pot or a coil, and even if you made such
adjustments to compensate for faulty circuitry ..... this is not a very
good
idea..... something is faulty, causing the symptoms you reported and it
must be fixed.... if you try to "adjust" the problem to make the
symptoms
go away, more expensive damage to more components can occur. Get it
fixed
properly right away.
Best Regards,
Daniel Sofie
Electronics Supply & Repair
------------------------------------------------

"Michael Gardner" <mgg@prairienet.org> wrote in message

Always some smart mouth electronics tech who can't offer any real help,
except to tell you to "fix it right".

Lets review. It is a 1986 tv set. It isn't worth fixing right if
fixing right takes more than an hour or a few dollars. This tv set was

Thanks
mgg
Real Working Engineer
------------------------------

Michael Gardner:
Have you actually verified that the power supplyB+ regulation circuitry is
working properly..... do you have a variac and a DMM to confirm proper
operation? Since the picture is too big both Horizontally and Vertically,
I would think that this would be the first place to look. It is not too
likely that faulty pincushion cicuitry could cause the vertical to be too
big..... although while looking around the flyback area, you should ESR
check the electrolytics particuarly the screen filtering components and
flyback derived B+ sources.
.......... and yes, fix it right or don't fix it at all......
...........it is a matter of safety.....
...........and it could easily take more than an hour or a few dollars.
--
Best Regards,
Smart mouth electronics tech
Daniel Sofie
Electronics Supply & Repair
..
..
..

 

[Michael Gardner]

In article <voimnbrl67410d@corp.supernews.com>,
"Sofie" <sofie@olypen.com> wrote:

snipped:
"Michael Gardner" <mgg@prairienet.org> wrote in message
news:mgg-3CD7A5.21411610102003@wildfire.prairienet.org...
Everything works on this 1986 Zenith TV, except the horizontal size is
way too big - losing about 25% of picture on one side (vertical
probably
a bit too big too). I can't visually find anything labeled
appropriately. Is this likely to be a pot/coil on the main board or
on
the back of the tube or related to B+ or something?
tnx
mgg
----------------------------------------

mgg:
Certainly, as you suggested, you should check the regulated B+ and
verify
that the B+ regulation circuitry is operating properly.
No, it is probably not a pot or a coil, and even if you made such
adjustments to compensate for faulty circuitry ..... this is not a very
good
idea..... something is faulty, causing the symptoms you reported and it
must be fixed.... if you try to "adjust" the problem to make the
symptoms
go away, more expensive damage to more components can occur. Get it
fixed
properly right away.
Best Regards,
Daniel Sofie
Electronics Supply & Repair
------------------------------------------------


"Michael Gardner" <mgg@prairienet.org> wrote in message

Always some smart mouth electronics tech who can't offer any real help,
except to tell you to "fix it right".

Lets review. It is a 1986 tv set. It isn't worth fixing right if
fixing right takes more than an hour or a few dollars. This tv set was

Thanks
mgg
Real Working Engineer
------------------------------

Michael Gardner:
Have you actually verified that the power supplyB+ regulation circuitry is
working properly..... do you have a variac and a DMM to confirm proper
operation? Since the picture is too big both Horizontally and Vertically,
I would think that this would be the first place to look. It is not too
likely that faulty pincushion cicuitry could cause the vertical to be too
big..... although while looking around the flyback area, you should ESR
check the electrolytics particuarly the screen filtering components and
flyback derived B+ sources.
......... and yes, fix it right or don't fix it at all......
..........it is a matter of safety.....
..........and it could easily take more than an hour or a few dollars.

I own and know how to a variac, a DMM AND an oscilloscope. I also know
the various circuits in a tv work. WE BOTH know, that tv manufactures
design those circuits in MANY different ways, thus without schematics or
a lot of experience with a particular manufacturer and generation of
equipment - its a matter of tracing out that part of the circuit. I
never claimed current TV repair experience - I wouldn't have asked the
question if I spent 40 hours a week fixing TVs. I was hoping for a bit
of relevant experience to be shared - but that was too much to expect.
I'll work it out without your help. I got two responses - and both were
far more interested in pointing out that an experience TV tech wouldn't
be asking such a question - well hell, that's brilliant. In other
words, this is our private club - go away.

I'm gone.

--
Best Regards,
Smart mouth electronics tech
Daniel Sofie
Electronics Supply & Repair
.
.
.

 

[Asimov]

"David" bravely wrote to "All" (11 Oct 03 22:46:08)
--- on the heady topic of "Re: Zenith sc2593l horizontal size hint? Second
try."

When I get my hands on a defective tv set I always go right to the
implicated circuitry and then uncover the defective part. Often I don't
need to use the scope at all. It's not about familarity with any
particular model but rather from a general experience of a variety of
types. I must have repaired many over the years though not many of the
same model in the same day.


Da> From: "David" <dkuhajda@locl.net.spam>
Da> There is a big difference between someone who was
Da> a parts swapper and a real technician who actually knew what they were
Da> doing.

.... You may be a tech if you're entertained by a 6-pack and sparking HV.

 

[Sofie]

Michael Gardner:
Geeeze..... what is your problem?
You were given several excellent troubleshooting suggestions and diagnostic
paths for you to follow....... we are sorry we couldn't tell you "exactly"
which faulty part you should replace and we are sorry that we could not
agree with you about making adjustments to compensate for faulty circuitry.
If you don't like the answers then don't ask the questions.....
.....another newsgroup that might interest you is alt.whiners.complainers
..... there you will find solace.
Best Regards,
Smart mouth electronics tech
---------------------------------------

snipped:

"Michael Gardner" <mgg@prairienet.org> wrote in message news:mgg-
I own and know how to a variac, a DMM AND an oscilloscope. I also know
the various circuits in a tv work. WE BOTH know, that tv manufactures
design those circuits in MANY different ways, thus without schematics or
a lot of experience with a particular manufacturer and generation of
equipment - its a matter of tracing out that part of the circuit. I
never claimed current TV repair experience - I wouldn't have asked the
question if I spent 40 hours a week fixing TVs. I was hoping for a bit
of relevant experience to be shared - but that was too much to expect.
I'll work it out without your help. I got two responses - and both were
far more interested in pointing out that an experience TV tech wouldn't
be asking such a question - well hell, that's brilliant. In other
words, this is our private club - go away.

I'm gone.