[TechAssist] Re: MAG: 25X6 chassis Quick Question?
- From: Dennis Viereck <wa6ati@xxxxxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Sun, 20 Jan 2002 08:43:12 -0800
On a Linear supply that light bulb arrangement will work great. On a SMPS I
still
like to put the bulb in series with the 130vdc B+ to the flyback. With this 25X6
chassis since it is a linear supply putting the bulb in series with the AC line
fuse works great as a dynamic current limiter.
And you know you don't have to use a socket on a board, You can use a all rubber
socket with two pigtail wires coming out of it. Just use clip leads to attach it
to the open fuse terminals.
Dennis Viereck
Edward Gaidies wrote:
> Perry;
> You don't need to solder a light bulb in. You make up a little jig, with the
> light bulb in series with an AC receptacle, on a little sheet of plywood.
> Then plug the TV under test directly into the AC receptacle.
>
> -Ed-
>
> >
> > Friends:
> >
> > We used to use the light bulb test on Motorola base stations to find shorts
> > after lightning strikes. If the bulb had a bright glow, you had shorts to
> > find. We just simply repaired circuits until the bulb went dim. But those
> > had a round screw in fuse the same size as a light bulb. We have found on
> > most TV's, if you run your powerite down to around 80 volts, you may not
> > blow any parts if the flyback is bad, however, the flyback will get warm, or
> > in some cases might even smoke a little. The best way though is to use a
> > Sencore VG92, and do a load test, with everything in circuit. It will check
> > your timing and loads, you will know in less than five minutes if your
> > flyback is bad. That is just what works for us. It is hard to get my young
> > techs to solder a light bulb socket into a little TV chassis. They try to
> > come up with quicker test. My 2 cents.
> >
> > Perry Bower
> > Electric Medic
> > "It's Cheaper to Keep Her"
> > 3850 Washington Road Suite 5b
> > Martinez, Georgia 30907
> > Phone: 706-8MEDIC4 (863-3424)
> > Phone: 706-863-3474
> > Fax: 706-863-2316
> > Website: www.electricmedic.com
> > mailto:info@xxxxxxxxxxxxxxxxx
> > "WE REPAIR WITH CARE"
> > More Info: www.augusta-ga.bbb.org/report.html?compid=6001278&national=y
> >
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> > Mitsubishi, Panasonic, Philips Magnavox, Pioneer, ProSCAN, RCA, Samsung,
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> >
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> >
> > -----Original Message-----
> > From: techassist-bounce@xxxxxxxxxxxxx
> > [mailto:techassist-bounce@xxxxxxxxxxxxx]On Behalf Of Dennis Viereck
> > Sent: Sunday, January 20, 2002 2:22 AM
> > To: techassist@xxxxxxxxxxxxx
> > Subject: [TechAssist] Re: MAG: 25X6 chassis Quick Question?
> >
> >
> >
> > No need to blow up any parts. Use a 40 watt light bulb in series with the B+
> > to
> > the flyback. Connect your oscilloscope to the collector of the horizontal
> > output
> > transistor. Set the scope to resolve a 600 volt PP signal at 10 micro
> > seconds
> > per division. Power up the set an look for a clean undistorted pulse with a
> > duty
> > cycle of 11.7 microseconds "OFF" time and a "ON" time of 51.7 microseconds.
> >
> > Any extra ringing or distortion means you have a heavy load on the secondary
> > or
> > an internal shorted winding.
> >
> > The light bulb saves components, and buys time to measure the "Must Haves"
> > in
> > that circuit. Sometimes only 2 or 3 seconds is necessary to make this
> > measurement. Most of the time after a short test like this and it is a
> > flyback,
> > one can feel the heat generated in the flyback by the bad winding or diode
> > stack.
> >
> > Dennis Viereck
> >
> > Bill McFarland wrote:
> >
> >> Hey no problem,
> >>
> >> The old "N" chassis used to do this all the time (The flyback was almost
> >> always bad)
> >>
> >> I was just wondering if anyone could say "Yea those crap the bed all the
> >> time!" It would give me a little more to go on when on Monday I use my
> >> "Stone-aged" BK 1077 to ring it. (Its only about 75% effective...And that
> >> only if the flyback is completely out of the unit)
> >>
> >> I hate blowing parts up!
> >>
> >> Funny thing is now that "I" am the one paying for the parts. I sure am a
> > lot
> >> more careful about things like this. When I worked for someone else it was
> >> faster to just change the HOT and Reg. and see if it blows the HOT back
> > up!
> >> (I was young...What can I say)
> >>
> >> Good luck, God Bless
> >> Bill McFarland
> >> DMC Electronics
> >> Salt Lake City, Utah
> >>
> >> ----- Original Message -----
> >> From: Dennis Viereck <wa6ati@xxxxxxxxxxxxxx>
> >> To: <techassist@xxxxxxxxxxxxx>
> >> Sent: Saturday, January 19, 2002 8:37 PM
> >> Subject: [TechAssist] Re: MAG: 25X6 chassis Quick Question?
> >>
> >>>
> >>> Opps... I can't read.... Never mind. You might be right......
> >>> Dennis Viereck
> >>>
> >>> Dennis Viereck wrote:
> >>>
> >>>> Depending on how the STR is shorted, I would the think the set would
> >> still
> >>>> run. Assuming the AC line voltage is reduced enough to achieve 130VDC
> > at
> >> the
> >>>> output of the regulator. This is a simple linear regulator and easily
> >>>> bypassed.
> >>>>
> >>>> A "Shorted" STR certainly would not point me in he direction of the
> >> flyback.
> >>>> Maybe if you had a shorted horizontal output transistor, I might feel
> >>>> inclined to agree with you. But certainly not on 1 shorted part and
> >>>> intestinal feelings......
> >>>>
> >>>> Dennis Viereck
> >>>>
> >>>> Bill McFarland wrote:
> >>>>
> >>>>> Hello all,
> >>>>>
> >>>>> I am working on a 25X6 Maggot-box.
> >>>>>
> >>>>> Shorted HOT, Bad STR30130 Regulator.
> >>>>>
> >>>>> My gut tells me the flyback is probably bad as well.
> >>>>>
> >>>>> Can anyone tell me if the Flyback is a common failure item in this
> >> unit?
> >>>>>
> >>>>> Good luck, God Bless
> >>>>> Bill McFarland
> >>>>> DMC Electronics
> >>>>> Salt Lake City, Utah
> >>>>>
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> --
> From: Ed Gaidies
> teltek@xxxxxxxxxxx
> Tel-Tek Electronics
>
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