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#1
08-06-2009, 10:27 AM
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Horiz Freq Coil question
Hi everyone, I'm working on a Stewart Warner Model 9014-B, Sams Set 105 Folder 10. In a nut shell I have no HV, the Horiz Mult tube pin 6 should be at 270VDC and it is at 0, I measured voltage across the Horiz Freq coil, I have 280VDC going in but only 2.7VDC coming out. What kind of voltage difference should i see across the coil? If It works the way I think it does the voltage will vary with the adjustment of the coil but this drop seems excessive. Any thoughts?
Thanks Chris 
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#2
08-06-2009, 12:36 PM
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It sounds like the coil is open. I would check the resistance and if it measures in the megohms, look for a break in one of the small wires that attach the coil to the terminals that connet it to the circuitry.
I have seen this kind of coil failure hundreds of times. Good luck! Keep us posted!
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#3
08-06-2009, 01:00 PM
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Your rite, the coil is open, one of the wires is broke. Now for the big question, how do i fix it? Can these tiny wires be soldered?
Thanks Chris
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#4
08-06-2009, 01:25 PM
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I generally use a single strand of line cord and extend the little piece so there won't be any strain on it.
Be careful not to move it around too much as they break off easy. If more stability is needed during working on it, solder it to the terminal first, then solder it to the wire. It takes a bit of patience but I've saved nealy all of the ones I've tried.
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#6
08-06-2009, 04:15 PM
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I have done this as well, on monitor width coils. You just need to be careful stripping a bit of insulation off the wire coming from the coil.
__________________
Chris Quote from another forum: "(Antique TV collecting) always seemed to me to be a fringe hobby that only weirdos did."
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#7
08-06-2009, 04:42 PM
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Got it, that single strand was a bear to get soldered but I got it. Now my ACHV is back, all the tube voltages in the Horizontal circuit are normal. I've got voltage at the cap of the HV rectifier, it will light a fluorescent bulb.
The problem I have now is I have no DCHV at the HV anode lead going to the picture tube. I'm thinking either the Doorknob cap or the 1meg resistor attached to the cap. Any thoughts on this problem? thanks for all the good information, Chris
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#8
08-06-2009, 10:12 PM
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Not to be glum, and I'm not trying to be an a$$, but you're not really posting a lot of info here. There are far more basic things you could be doing, such as testing the flyback for continuity, looking for bad caps in the HV cage and horiz oscillator circuit (both my current sets had that problem), open HV rectifier(s), bad wiring, and on and on. One thing you should do regardless of anything else, is replace all the HV wiring- that is, the wires on the HV rectifier filament, and the anode wire itself. The HV wires on my Philco were very bad, I wouldn't power it up without replacing them. 15,000 volts of leakage isn't good.
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#9
08-07-2009, 11:52 AM
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Usually the doorknob cap goes leaky. I would power the set up without the cap in place. Just make sure the socket is far enough away to prevent arcing to the chassis. Also, check the high voltage rectifier tube. A shorted doorknob cap can kill this tube. I would change the wires but they usually will puncture and arc or burn if they are bad. The doorknob cap filters out the ripple from the high voltage rectifier. I have had slight problems with picyure tubes where the aquadag fell off and the capacitor ation of the tube was too low to hold a good charge but my Motorola TS-18 plays fine with no aquadag left at all.
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