Sanyo TV Model DS1930 Problem

[Joe]

Hello,

I have a Sanyo DS19380. When the power on button is pushed, I can
hear the relay click, then a few seconds click again. There is no
power after that. This happened after I tried to hook up a scope to
the tuner and tried to use one of the tuner case supports as ground.

If anyone has an idea as to what that could have done to prevent
powering on I would appreciate it.

If I need to replace the whole chassis, do you know of a good source
and would that be a cost effective way of fixing the tv.

Thanks a lot in advance

 

[Injundavecoal]

What you did was to connect a HOT tv chassis that has a live ground
with the earth ground of your scope. There is no way to tell how much
damage you did to the tv set. A qualified and experienced technician
would/should have realized it was a hot chassis and only worked on the
set with it plugged into an isolation transformer for safety (for
himself, the tv set, and the test equipment.

25 years ago I had this problem with these hot chassis/grounded scope voltage
differentials, and my boss, who was an electronics teacher and aerospace
engineer had the problem repaired in 10 seconds. "Clip that damn 3rd prong off
your scope cord" he said. I did, and 25 years has passed and I've burned up
zero TVs, zero scopes, and been shocked zero times. I know this is "extremely
dangerous" so I expect the "don't do this or you could be killed" responses, so
I'll just say I'd rather be unsafe and never get shocked or burn up equipment,
than be safe, get shocked and burn up scopes and TVs every time you hook a
scope probe accidently to a hot chassis TV.

 

[Jerry Greenberg]

You blew the (!@#@!) off the power supply. Start by checking
everything in the path from the AC coming in through any series
resistors, and then on to the bridge. In many TV sets there are some
low omage resistors, chokes, and etc along the AC input path. Then go
on to the bridge rectifier. There are more than excellent chances are
that rectifier has been blown.

I have seen guys also do some damage to their scopes. You will soon
know.

You should be working with an isolation transformer to drive the set
before connecting any test gear to it. You can be badly injured!

Since one side of the power supply has been shorted to earth ground,
there is a chance that there is a lot more damage in other areas after
you fix the supply. You will find out once you get the supply up to
specs. Maybe you will be lucky this time...

Also, just to make a comment, this only one of the many reasons why I
tell people that if they are not properly trained for TV service, even
if they are electrical engineers, they should not be inside their TV
sets, or microwave ovens. These can be very dangerous to mess with.

Jerry Greenberg
http://www.zoom-one.com

--




Joe <polya@frontiernet.net> wrote in message news:<oonpjvkt4gmh7gkighefjipj5qipv6rc65@4ax.com>...

Hello,

I have a Sanyo DS19380. When the power on button is pushed, I can
hear the relay click, then a few seconds click again. There is no
power after that. This happened after I tried to hook up a scope to
the tuner and tried to use one of the tuner case supports as ground.

If anyone has an idea as to what that could have done to prevent
powering on I would appreciate it.

If I need to replace the whole chassis, do you know of a good source
and would that be a cost effective way of fixing the tv.

Thanks a lot in advance

 

[Leonard G. Caillouet]

What you did will work in many cases, but you are taking a risk that seems
sort of silly. An isolation transformer isn't that expensive.

Leonard Caillouet

"Injundavecoal" <injundavecoal@aol.com> wrote in message
news:20030815182114.25445.00000040@mb-m15.aol.com...

What you did was to connect a HOT tv chassis that has a live ground
with the earth ground of your scope. There is no way to tell how much
damage you did to the tv set. A qualified and experienced technician
would/should have realized it was a hot chassis and only worked on the
set with it plugged into an isolation transformer for safety (for
himself, the tv set, and the test equipment.

25 years ago I had this problem with these hot chassis/grounded scope
voltage
differentials, and my boss, who was an electronics teacher and aerospace
engineer had the problem repaired in 10 seconds. "Clip that damn 3rd prong
off
your scope cord" he said. I did, and 25 years has passed and I've burned
up
zero TVs, zero scopes, and been shocked zero times. I know this is
"extremely
dangerous" so I expect the "don't do this or you could be killed"
responses, so
I'll just say I'd rather be unsafe and never get shocked or burn up
equipment,
than be safe, get shocked and burn up scopes and TVs every time you hook a
scope probe accidently to a hot chassis TV.