[TechAssist] Re: Sansui COM7200 tv/vcr Kevin &George
- From: "George" <grndmstrg@xxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Mon, 9 Jun 2003 15:29:28 -0700
Paul,
I use a piece of wire to loop through the FBT core and while ringing out of
circuit short the ends, if the ringing drops dramatically the coil is most
likely ok. If it has little or no effect the coil is bad. However you still
should do the drive test to verify that the diodes are good (Sencore tech
tip #117 as an example). Somebody mentioned on another post that some good
Sony FBT tested lower than the Sencore reference charts. Tip was promoting
the Sencore VA62. You can use any suitable driver source.
George
Afana Electronics
Moreno Valley, CA
grndmstrg@xxxxxxxxxxxx
----- Original Message -----
From: "Paul" <dntwntv@xxxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Monday, June 09, 2003 11:44 AM
Subject: [TechAssist] Re: Sansui COM7200 tv/vcr Kevin &George
> I guess that I was trying to be logical in tracing the problem. I did ring
the IHVT out of circuit and it rang 41 on one setting a little less on some
others. Using sencoreVA62. So I agree with both Kevin and George. Where my
logic seems to have gone south is that with the ground hooked up the
transformer would only ring about 4. If the ground dampens the rings from
the test equipment, doesn't it also dampen the rings that are generated in
circuit? Or is the signal from the test equipment that much weaker? I also
pulled the pic tube socket and this improved the number of rings. This is
probably normal because the filament winding goes to ground also. What I did
was to unsolder all but the ground and the filament winding and then bridge
each pin one at a time to see if one would dampen the rings. This is where I
started questioning my logic.The only ones that had a dramatic affect was
the one leg that goes to the pcc I think,and (I had disconnected every thing
in that circuit)
> , also ground and the filaments.Which are there normally. I haven't
replaced the the driver xfmr yet as suggested by several others. Will let
you know after that is done. Paul
> George <grndmstrg@xxxxxxxxxxxx> wrote:Kevin,
>
> Your missing the point for the Sencore recommended method, it points the
way
> to the probable defective circuit. As you disconnect the loads if the FBT
> starts to ring more normal you have located a trouble shooting path to
> pursue. It helps to do some logical diagnostics at the same time.
>
> George
> Afana Electronics
> Moreno Valley, CA
> grndmstrg@xxxxxxxxxxxx
>
> ----- Original Message -----
> From: "Kevin"
> To:
> Sent: Saturday, June 07, 2003 12:34 AM
> Subject: [TechAssist] Re: Sansui COM7200 tv/vcr
>
>
> > It is best to ring flybacks out of circuit, because in my experience
> > most flybacks will not ring in circuit. My Sencore suggests to ring the
> > flyback in circuit and then if it rings bad, to remove the yoke and keep
> > disconnecting things until it rings good. To me the easiest thing to do
> > is to first remove the flyback and then see if it rings. Just my 2
> > cents.
> >
> > Kevin Wilks
> > Kevin's TV & Video Repair
> > Penticton BC Canada
> > kevintv@xxxxxxx
> >
> >
> > -----Original Message-----
> > From: techassist-bounce@xxxxxxxxxxxxx
> > [mailto:techassist-bounce@xxxxxxxxxxxxx] On Behalf Of John at Main TV
> > Sent: Friday, June 06, 2003 3:06 PM
> > To: techassist@xxxxxxxxxxxxx
> > Subject: [TechAssist] Re: Sansui COM7200 tv/vcr
> >
> > I am pasting the fix I posted for this model a few weeks ago. BTW, the
> >
> > fly will not ring good in the circuit because of PCC transistor Q409
> > even though the transistor is good. John...........
> > This Sansui COM7200(made by Orion in 2002 - 27" combi) gave me a lot of
> > trouble. The horizontal output transistor had B+ and (some) drive on
> > the base (1.6 volt p/p) but no HV. The problem turned out to be the
> > horiz. drive transformer, Orion 0450190161. I compared the new
> > transformer to the old one and the DC resistance was almost identical,
> > however the inductance reading on the primary of the old one was half
> > the new one (40mh compared to 72mh on new one). The base signal on the
> > working set is 12v p/p. Thanks to Mark Goldspiel and Jerry Silverman for
> >
> > suggesting the transformer as the problem.
> > --
> >
> > Paul wrote:
> > > I'm am trying to pin down the reason for no high voltage. This was
> > made by Emerson I believe. I do not have service lit. for this set. I
> > have replaced the HOP xstr. I have soldered the IHVT & driver
> > transformers as well as other associated circuitry. I have removed and
> > rung the IHVT. HOPxstr.has 130v on collector.What I don,t have is a
> > wave form of any significant size or shape on HOP collector. So I
> > disconnected the collector checked the wave form on the base of the
> > HOPxstr. Wave form is good.My logic was OK then, it has to be in the
> > secondary some place. But where? Well, I reasoned If I unsolder the
> > primary connect the ringer and unsolder one secondary at a time it
> > should show up. As I unsolder-ed each pin it finally rang good(went
> > from4to41).Great I said thats the leg that is bad. Wrong! I chased that
> > circuit till I found a place to disconnect every thing on it. No help. I
> > continued to unsolder the next couple of pins on the IHVT finally came
> > to one that let the ringer
> > go
> > > back to 41. It was the ground.The question is where is my logic
> > faulty? Am I expecting to much from the ringer? Sorry for the rambling?
> > Paul
> > >
> > >
> > > Paul ,B
> > Central TV&Video
> > Grover Beach Ca.
> > >
> > >
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> >
> > --
> > John Mielke
> > Main TV
> > Longmont,Co 80501
> > 303 776 6955
> > 303 776 0792 fax
> > maintv@xxxxxxxxxxx
> >
> >
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> Paul ,B
Central TV&Video
Grover Beach Ca.
>
>
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