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Crumbtrail TV Forums: TV Equipment: TV Repair Forum:
about H.O.T

 
 


torobo
New User

Apr 22, 2011, 3:02 AM

Post #1 of 6 (1035 views)
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about H.O.T Can't Post
Hi guys,
I just want to ask,how do I correctly check the Horizontal Output Transistor? Frown
there are many types of transistor used and testing using multimetre gives crazy results. Crazy
any help is appreciated. Laugh



jts1957
Veteran


Apr 22, 2011, 7:40 AM

Post #2 of 6 (1028 views)
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Re: [torobo] about H.O.T [In reply to] Can't Post
Diode junction (PN) is a diode junction is a diode junction .... UNLESS there is a low value resistance in parallel (internally or externally). Some outputs contain a internal Damper diode (still a PN junction). Always best to either float (min) two leads or test "out-of-circuit."Smile
When in doubt - compare readings against a "known-good" device of the SAME type (number).Angelic


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Location: Far, Far Away


TVparts4salesux
New User

Apr 22, 2011, 2:24 PM

Post #3 of 6 (1022 views)
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Re: [torobo] about H.O.T [In reply to] Can't Post
Check ohms from Collector to Emitter. If it's shorted it will show zero ohms. You can do this in circuit. Of course other things in the power supply can be shorted and not the transistor itself, so remove from circuit to recheck. No need to worry about any other checks with an ohmmeter. This is the only check needed 99+% of the time. Yes once in a while they will short E-B or open, but not often enough to spend any time thinking about in reality.


torobo
New User

Apr 22, 2011, 3:15 PM

Post #4 of 6 (1019 views)
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Re: [torobo] about H.O.T [In reply to] Can't Post
thanks for the tips,guys Wink
how about finding the B+ pin of Flyback Transformer?
and the proper way of testing it. Laugh
I usually test it by using multimeter and testing the resistance from B+ to GND but not all PCB writes down the B+ pin so im having problem to find the correct pin to test it Mad


jts1957
Veteran


Apr 22, 2011, 10:40 PM

Post #5 of 6 (1014 views)
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Re: [torobo] about H.O.T [In reply to] Can't Post
B-Plus pin of flyback will always connect to main power supply/SMPS.

With flyback pulled from board, B-Plus pin will be only foil with 95VDC or more on it.

Schematic will show - easiest.


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Location: Far, Far Away

(This post was edited by jts1957 on Apr 22, 2011, 10:55 PM)


Ron.M
Veteran


Apr 22, 2011, 10:46 PM

Post #6 of 6 (1011 views)
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Re: [jts1957] about H.O.T [In reply to] Can't Post
jts1957;.....

So will HOT collector thru flyback & winding for Video out transistors depending on model , CRT etc....Wink....
Usually about 200 vdc...
He needs to visually trace the wiring to the PS....Wink....
Meter will lie...

Later...Ron.M....Cool....
Veteran & Retired TV technician

(This post was edited by Ron.M on Apr 22, 2011, 10:49 PM)

 
 
 


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