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Author Topic: Strange Hantarex problem  (Read 1346 times)

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menace

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Strange Hantarex problem
« on: January 06, 2005, 07:57:13 am »
Since my schematic reading skills are amateur to say the least I just wanted to confirm that pins 9 and 10 on the crt socket are in fact the two heater leads to the tube.  Also, if i was doing a randy fromm special on this to remove the heater to cathode short would w6 and w7 be the appropriate wires to wrap around the ferrite core of the flyback?

Of course, if i can get a rejuvenator off ebay for cheap the question might be moot--but I would still like to know just for knowing's sake.
« Last Edit: February 08, 2005, 07:40:39 pm by menace »
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Ken Layton

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Re: hantarex Heater question
« Reply #1 on: January 06, 2005, 10:30:17 am »
Yes, you are correct.

menace

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Re: hantarex Polo 27" Heater question
« Reply #2 on: January 07, 2005, 02:17:22 pm »
ok, i wrapped a wire 2.5 turns around the ferrite  and then fed them to the heater wires and fired it up.  After rapidly ticking for about 10 or 20 seconds (sounds like its shorting??) I get a picture with scan lines running through it and the monitor will then tick more slowly.  Occasionally stopping but then the image goes back to a blurred state (where i started from).  Any thoughts anyone?--I know getting this to work is a longshot at best but its an interesting problem and would like to at least increase my knowledge a little.
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Ken Layton

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Re: hantarex Heater question
« Reply #3 on: January 07, 2005, 06:14:16 pm »
If you're trying the neckboard trick from Randy Fromm, you must disconnect the circuit that was powering the heater. I usually unsolder the entire socket from the neckboard and lift pins 9 and 10. Then I connect the wires I wrapped around the flyback core to the lifted pins and resolder the socket to the neckboard.

menace

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Re: hantarex Heater question
« Reply #4 on: January 08, 2005, 07:45:36 am »
yeah, thats what I'm up to alright--I have isolated pins 9 and 10 from the circuit while leaving the original wires to the neckboard intact-  Its very strange all the symptoms say heater cathode short but when i test the tube directly it checks ok--the only pins with any continuity between them are pins 4 (not used) and pins 9 and 10.  I'll have to recheck my results and see if there's something i missed.
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menace

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Re: Strange Hantarex problem
« Reply #5 on: February 08, 2005, 07:46:36 pm »
So i got looking at this again following the randy fromm flowchart.  I checked TP6 at first startup and its 137.8--ok, but its a very bright image with scan lines--it then makes a few soft clicks and the voltage drops down to 126 or so.  On a whim I replaced ic1--no change, i tested ZD101 and replaced C112 and C114, no change.  It looks like a HK short (screen control makes no difference, nor does bright control) but I have tested the tube backwards and forwards and get no shorts between pins. 

So my question is, what would cause the symptoms of an hk short without one being present?
« Last Edit: February 08, 2005, 08:02:45 pm by menace »
its better to not post and be thought a fool, then to whip out your keyboard and remove all doubt...