Tatung 26MDA monitor with Sparking sound

[Rodders]

I have a Tatung 26MDA multimedia display that after about a minute there
is the sound of a spark and the screen shuts off. The main power supply
is still running and the crt filaments are still glowing, seems to be
the eht that shuts off. The spark sound seems to come from the neck
board or the yoke, I have not been able to locate the exact spot yet.
The only label on the chassis is FM-2950 do not know if this is a model
number.

I have not been able to find any info on the web about this monitor,
even the tatung website does not list it. The closest I could find was
the 27MDA and even that had very little info.

Any help would be greatly appreciated

Rodney

 

[louiiv.com@_not_red_or_green_yonder.co.uk]

Dear Rodney

Sounds like you have done most of the fault tracing and the tubebase
panel is in question.

Tubebase connector Focus spark gap would be my first port of call.

Assuming it is arcing in error, you can try locating the sparkgap with a
view to checking/maximizing its gap.

regards

Frank

 

[Rodders]

Dear Rodney

Sounds like you have done most of the fault tracing and the tubebase
panel is in question.

Tubebase connector Focus spark gap would be my first port of call.

Assuming it is arcing in error, you can try locating the sparkgap with a
view to checking/maximizing its gap.

regards

Frank

The spark gap for the focus is an air gap in the tube socket. I used a
piece of paper to block the gap and still got a spark sound and no mark
on the paper. Have been unable to find any trace of arcing anyware on
the board. After listening a bit more the sound could be coming from the
lopt it's hard to tell due to position of the boards and me been not to
keen to get my head too close to the eht. I have removed the lopt but
found no trace of arcing.

It also looks like someone has worked on the monitor before as all the
spark gaps on the neck board have been cut.

Thanks
Rodney

 

[louiiv.com@_not_red_or_green_yonder.co.uk]

Dear Rodney

Here is a good one. Try viewing the LOPT and Tubebase in reduced
ambient light (Total dark if you can).
Light from spark may be visible (if you are lucky) or a corona visible
near the offending part.

Tatung monitors are great for the price and generally are better than
most that are out there so it may be worth that extra bit of effort.

regards

Frank

 

[Ian French]

The spark gap for the focus is an air gap in the tube socket. I used a
piece of paper to block the gap and still got a spark sound and no mark
on the paper. Have been unable to find any trace of arcing anyware on
the board. After listening a bit more the sound could be coming from the
lopt it's hard to tell due to position of the boards and me been not to
keen to get my head too close to the eht. I have removed the lopt but
found no trace of arcing.

It also looks like someone has worked on the monitor before as all the
spark gaps on the neck board have been cut.

Thanks
Rodney

Hi Guys,

Sometimes the tube itself can be the cause of "Sparking Problems".
If air gets in the tube (due to a very slow leak over years or a cracked
tube neck) then it will flash over INSIDE the tube. To diagnose this, turn
off the room lights and look for blue/violet light inside the neck of the
tube.
If you get this then there are only 2 possibilities, Air in tube, or too
many volts. You will need to measure the EHT to eliminate the latter.

Good luck!

Ian.