Hantarex problem ( newbie )

[jclaeys]

I'm still trying to figure out what's wrong with my Hantarex MTC 900.

Previously, when I powered up, for about 1-2 seconds blue sparks appeared in the cathode tube .

I was able to  disable the shut-down circuit.

The only thing that changed after that, was the fact that the blue sparks ( along with a buzzing noise ) remain in the cathode untill I power down.

Does anyone have an idea what to test next to pinpoint the problem ?

Does it sound like the LOPT has given up ?

[Ken Layton]

Blue sparks inside the picture tube neck? Then that means your picture tube is SHOT! There's a hairline crack in the tube somewhere (could be anywhere) and air has gotten inside. The tube is total garbage now and you'll need to buy a new picture tube or scrounge a good used one for a 'tube swap'.

[jclaeys]

The picture tube does look ok. I don't see any cracks, not even scratches.

Any chance a LOPT/flyback replacement might help ?

[rchadd]

if ken says so - to must have had it

[jclaeys]

Sorry, I didn't know I offended anyone ...

[Ken Layton]

I'm not offended.

Anytime there are visible sparks inside the neck of the picture tube that generally indicates the vacuum of the tube has been compromised and air has gotten in. No vacuum = shot tube. Connecting the tube to a restorer/analyzer (a.k.a. rejuvenator) will confirm.

Remember that just because you don't see a crack doesn't mean there isn't a crack in the glass. The crack can occur underneath the white plastic tube socket, under the yoke, under the white gripping tape the purity magnets sit on, under the metal band that wraps around the face, etc.

[jclaeys]

Thanks !