[TechAssist] Re: Horizontal output overheating.
- From: "Vilhelm Boor" <villyboor@xxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx, techassist@xxxxxxxxxxxxx
- Date: Tue, 17 Dec 2002 09:06:35 0000
Villy Boor
Boorelec Durban
Would like to thank all who participated in my survey especially Al and D
Punday To those who recon there is no price differential, where have you been
Some are 10 times the price so using a 2SC1234 from Joes parts Store at $2 or
the same 2SC1234 from Sony at $20 and the $20 job goes up in smoke under
warranty, perhaps Sony bought there's from Joe. Thank you I have a family to
feed, there is little enough profit in this job to hand it over to the
manufacturers. I worked for a manufacturer for 24 years, Their cost for parts
had little relationship to the part, They worked on a store box price, A box in
the store made a profit of X
so if you sold 2 parts from that box cost was part price plus X over 2 you
aught to gave seen some of the prices, several hundred dollars for a 10C
transistor.
May I stress here I did not work for Sony so their foibles are a mystery to
me. Vilhelm Boor.
--
On Mon, 16 Dec 2002 22:27:41
Al Gutz wrote:
>
>Paralleling transistors is not a problem, if one starts to conduct more
>it gets hotter and its effective resistance increases causing the other
>cooler transistor which has a lower effective resistance to pickup more
>of the load. A point of balance is reached. I have worked on high power
>broadcast applications where you may have many transistors or mosfets in
>parallel. When you are looking for outputs of up to 50 Kwatts you don't
>do it with one transistor. This aside I don't know if I would do it with
>a HOT. You can safely sub these provided you pay attention to switching
>times and transition times, max CE volts, Max BE volts and total Pout.
>If you sub and keep transition/switch times the same its no problem to
>increase the Imax ans Pout. ei 2SD1879, 1880, 1881 all have same specs
>except for Imax and Pout.
>
>Al G
>Al's TV-Electronics
>Pembroke Ont.
>Canada
>
>Gary McCartney wrote:
>>
>> 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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