Need some SMPS repair tips needed.

[Jim Flanagan]

Hello.
I am attempting to track down an intermittent arc (I think, but not
sure). My test equipment instrument has a crt circuit with an 11KV
anode and 2.75K screen. Maybe, once every half hour or so, I get a
flicker that leads me to believe that the HV is arcing somewhere.
I am not totally sure whether this is in the secondary side of the
transformer or the switching, primary side.

Here is what I have done so far:

Looked for parts around the HV area that looked like arcing had
occurred. Found none.

Checked the screen voltage and found that it was in spec.

Used an insulated tool to 'poke' around the HV area looking for
poor solder joints, etc. None found.

I have not looked at the primary side. I need to obtain an isolation
transformer first.

Checked for dirt, etc, around the anode which could cause arcing.
The SMPS circuit board is VERY clean. I, however, used compressed air
to gently blow off any residual dust, etc.

My main question, how can I isolate the problem to either the secondary
side of the transformer or the switching primary side? If this is a
failing capacitor, It would be nice to know which side of the xfmr this
is occurring.

Well, any tips that you can throw my way would be appreciated.
Thanks.
-jim
WB5KYE

 

[ian field]

Hello.
I am attempting to track down an intermittent arc (I think, but not
sure). My test equipment instrument has a crt circuit with an 11KV anode
and 2.75K screen. Maybe, once every half hour or so, I get a
flicker that leads me to believe that the HV is arcing somewhere.
I am not totally sure whether this is in the secondary side of the
transformer or the switching, primary side.

Here is what I have done so far:

Looked for parts around the HV area that looked like arcing had occurred.
Found none.

Checked the screen voltage and found that it was in spec.

Used an insulated tool to 'poke' around the HV area looking for
poor solder joints, etc. None found.

I have not looked at the primary side. I need to obtain an isolation
transformer first.

Checked for dirt, etc, around the anode which could cause arcing.
The SMPS circuit board is VERY clean. I, however, used compressed air
to gently blow off any residual dust, etc.

My main question, how can I isolate the problem to either the secondary
side of the transformer or the switching primary side? If this is a
failing capacitor, It would be nice to know which side of the xfmr this is
occurring.

Well, any tips that you can throw my way would be appreciated.
Thanks.
-jim
WB5KYE

Boil a kettle in the same room - any points of flashover will soon show
themselves!

 

[David Naylor]

Hello.
I am attempting to track down an intermittent arc (I think, but not
sure). My test equipment instrument has a crt circuit with an 11KV
anode and 2.75K screen. Maybe, once every half hour or so, I get a
flicker that leads me to believe that the HV is arcing somewhere.
I am not totally sure whether this is in the secondary side of the
transformer or the switching, primary side.

Here is what I have done so far:

Looked for parts around the HV area that looked like arcing had
occurred. Found none.

Checked the screen voltage and found that it was in spec.

Used an insulated tool to 'poke' around the HV area looking for
poor solder joints, etc. None found.

I have not looked at the primary side. I need to obtain an isolation
transformer first.

Checked for dirt, etc, around the anode which could cause arcing.
The SMPS circuit board is VERY clean. I, however, used compressed air
to gently blow off any residual dust, etc.

My main question, how can I isolate the problem to either the secondary
side of the transformer or the switching primary side? If this is a
failing capacitor, It would be nice to know which side of the xfmr this
is occurring.

Well, any tips that you can throw my way would be appreciated.
Thanks.
-jim
WB5KYE

what brand of set do you have. Toshiba has a problem with the silicon
they use around the anode lead of mostly the RED crt. it arcs to the
yoke , sometimes it will shut down the set or blow the HOT and fuse on
the deflection board . My suggestion is to recoat all three guns at the
anode don't be stinchy use alot should take care of it..if it is and
RCA then it is the HV slitter you can replace it or just relase it from
its mounts and it will run forever no more arc...