[TechAssist] Re: Horizontal output overheating.

 Villy Boor
  Boorelec Durban
  I am sorry but I have to reply to this, base current in an output transistor 
of this type is a non issue, Some have 30 ohms or so emitter across to the base 
and the resistance  of the transformer is 10 times less. My solution is not a 
home brewed cure, it is what was done 30 or so years ago when the first 
transistors produced could not do the job asked of them and this was the 
solution Re Philips K9 and an RBM whose model escapes me, so no glory can be 
claimed by the writer for this solution to the larger screen TV blowing 
transistors.
--

On Mon, 16 Dec 2002 18:14:05  
 Jerry wrote:
>
>I would think there would also be problems driving two transistors. Since
>BJT's are current operated devices, the base drive current would be have to
>be divided between the two, neither would be correctly driven...
>
>Jerry Eiting   geiting@xxxxxxxxxx
>Christians Electronic Service
>Piqua, Ohio
>
>
>----- Original Message -----
>From: "Jose Reyes" <jr@xxxxxxxxxxx>
>To: <techassist@xxxxxxxxxxxxx>
>Sent: Monday, December 16, 2002 10:13 AM
>Subject: [TechAssist] Re: Horizontal output overheating.
>
>
>|
>| I have heard of the same thing,
>| because their switching times are different.
>| One will start conducting before the other,
>| hence, use most of the current.
>| Unless small value resistors are installed.
>| I never read up on this, just repeating what I was told.
>|
>| Jose' Reyes
>| @ Kwik Fix TV
>|      619 Pondella Rd.
>|      N. Ft. Myers, Fl.  33903
>|      E-Mail:    jr@xxxxxxxxxxx
>|
>| ----- Original Message -----
>| From: "Gary McCartney" <gary@xxxxxxxxxxx>
>| To: <techassist@xxxxxxxxxxxxx>
>| Sent: Monday, December 16, 2002 10:01 AM
>| Subject: [TechAssist] Re: Horizontal output overheating.
>|
>|
>| >
>| > I always read that using two semiconductors in parallel will cause the
>| > one of them to hog all the current, unless you install a small current
>| > limiting resistor (perhaps 0.01 ohm or there abouts) in the paths of the
>| > 2 emitters. Has anyone else heard of this?
>| >
>| >
>| >
>| >
>| > Gary McCartney
>| >
>| > McCartney Electronics
>| > 7134 Fife Rd, RR 7
>| > Guelph Ontario Canada N1H 6J4
>| > Fax: (519)821-1530
>| > email: gary (at) number63.ca
>| >
>| >
>| >
>| >
>| >
>| >
>| > teltek2 wrote:
>| > >
>| > > I agree...using 2 will put you into price range of OEM.
>| > >
>| > > Fix the fault..install OEM part, ship it. Done.
>| > >
>| > > -Ed-
>| > > Tel-Tek Electronics
>| > > Ontario-Canada
>| > >
>| > > teltek2@xxxxxxxxxxxx
>| > > ----- Original Message -----
>| > > From: <HSWAD@xxxxxxx>
>| > > To: <techassist@xxxxxxxxxxxxx>
>| > > Sent: Monday, December 16, 2002 9:09 AM
>| > > Subject: [TechAssist] Re: Horizontal output overheating.
>| > >
>| > > > Wouldn't it be about the same price to replace with the correct
>part?
>| > > > Modifications put you in a responsible position . Hollis Bates,
>field
>| > > > engineer-retired                       In a message dated 12/16/02
>| 5:13:25
>| > > AM
>| > > > Eastern Standard Time, villyboor@xxxxxxxxx writes:
>| > > >
>| > > >
>| > > > > Subj:[TechAssist] Re: Horizontal output overheating.
>| > > > > Date:12/16/02 5:13:25 AM Eastern Standard Time
>| > > > > From:<A HREF="mailto:villyboor@xxxxxxxxx";>villyboor@xxxxxxxxx</A>
>| > > > > Reply-to:<A
>| > > HREF="mailto:techassist@xxxxxxxxxxxxx";>techassist@xxxxxxxxxxxxx</A>
>| > > > > To:<A
>| > > HREF="mailto:techassist@xxxxxxxxxxxxx";>techassist@xxxxxxxxxxxxx</A>,
><A
>| > > HREF="mailto:techassist@xxxxxxxxxxxxx";>techassist@xxxxxxxxxxxxx</A>
>| > > > > Sent from the Internet
>| > > > >
>| > > > >
>| > > > >
>| > > > >
>| > > > > Villy Boor
>| > > > > Boorelec Durban
>| > > > > --
>| > > > >   Perhaps I am a wee bit off the topic but I have been finding
>many
>| TVs
>| > > > > with troubles after the horizontal output has been changed. What I
>| find
>| > > is
>| > > > > if you get the expensive manufacturers transistor all is well, the
>| > > generic
>| > > > > fails. My tip here is use 2, parallel them up and there is no need
>| to
>| > > > > increase heat sinks as there will be less heat, the input
>inpedance
>| > > drops
>| > > > > so it is more stable, as yet after 2 years on sets where no faults
>| were
>| > > > > found and the transistor failed, I have had no returns. Your
>| comments
>| > > > > welcomed, Villy.
>| > > > > On Sun, 15 Dec 2002 08:13:25
>| > > > > Paul Medvetz wrote:
>| > > > > >We have a Sony KV-32S35 , Set came in dead with shorted
>horiz.out,
>| > > > > reg.Q601 and Q602, Replaced Q601,Q602, Q502, VDR601,R607,C502.Set
>| now
>| > > plays
>| > > > > but Q601,Q602, get very hot just after three minutes,This set was
>in
>| > > shop
>| > > > > two months ago for shorted flyback and horiz.out transistor.Don't
>| want
>| > > to
>| > > > > leave it on any longer I know it will short again,Also I did go
>over
>| > > > > connections in horiz. thanks in advance for any help.
>| > > > > >
>| > > > > >Paul Medvetz
>| > > > > >TV- Service-CO.
>| > > > > >Hazleton,Pa. 18202
>| > > > > >paulcho@xxxxxxxx
>| > > > > >
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