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JTS1957
Joined: 21 Jan 2009
Posts: 1331
Location: Far, Far Away
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 Posted: Sun Jul 26, 2009 8:35 pm Post subject: |
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Considering the confusion about "grounds," How did you "TEST" the transistors?
R826 = O.K.
D830 goes between cold ground and D809 cathode (line) (C822 "+", one side of C821, and R2301 are also on this "foil."
If you tested those three transistors satisfactorily, I'm ready to say: "Change IC803."  |
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chumba
Joined: 01 Jul 2009
Posts: 66
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| Posted: Mon Jul 27, 2009 2:27 pm Post subject: |
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The Q's were tested good as you described earlier with diode test mode: B to E = ~0.4 either polarity, B to C = open on one polarity & 0.4 on reverse, C to E = open / 0.4.
I measured them this way 1st in-circuit, and if I got the correct reading I didn't remove it and re-test. Is that OK?
Do any capacitors need to be checked?
Also what is the function of IC803 and can you recommend a good mail order parts source? |
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JTS1957
Joined: 21 Jan 2009
Posts: 1331
Location: Far, Far Away
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| Posted: Mon Jul 27, 2009 4:43 pm Post subject: |
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The transistor I told you how to check earlier was a Horizontal Output. It (in this case) had a built-in resistor and diode internally. (2 junctions= Hi & a reading / 1 junction = same both ways)
The ones in the power supply are standard transistors. (2 junctions= hi & a reading / 1 junction= hi both ways) They should test (Out of circuit):
B to E = infinity with leads one way - a ~.4 reading leads the other way;
B to C = infinity with leads one way - a ~.4 reading leads the other way;
C to E = infinity with leads either way.
If you obtain a suspicious reading, isolate (float) two leads of that transistor. (Q802 for example, has a diode across BE)
The only two capacitors you may want to check would be C815 and C820.
IC803 is the Regulator device STR58041A (MCM is one place I have used - double check # on part) http://www.mcmelectronics.com/product/DISTRIBUTED-BY-MCM-/STR58041Z |
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chumba
Joined: 01 Jul 2009
Posts: 66
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| Posted: Tue Jul 28, 2009 7:58 pm Post subject: Panasonic CT-27G32V - dead TV with click |
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Ok, testing that way Q802 tests good (and also D830 tests good). But Q801 (type C1685 R.72) tests strange in diode mode:
C to E measures infinite, & 0.6 with leads reversed and same for B to C.
B to E measures 0.25 with either polarity 
In R mode:
C to E measures infinite, & 1.6 Megohm with leads reversed and same for B to C. B to E measures 487 ohm with either polarity.
Does these junctions need to be float tested? If so how is that done ? |
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JTS1957
Joined: 21 Jan 2009
Posts: 1331
Location: Far, Far Away
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| Posted: Tue Jul 28, 2009 10:13 pm Post subject: |
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| Pull that transistor out after marking board or drawing a diagram so you can be absolutely sure to reinstall correctly. And test it out of circuit. |
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chumba
Joined: 01 Jul 2009
Posts: 66
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| Posted: Thu Jul 30, 2009 5:24 pm Post subject: Panasonic CT-27G32V - dead TV with click |
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| Both Q801 & Q802 were removed from board when I tested them. |
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JTS1957
Joined: 21 Jan 2009
Posts: 1331
Location: Far, Far Away
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| Posted: Thu Jul 30, 2009 7:02 pm Post subject: |
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Q801 is bad then.  |
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chumba
Joined: 01 Jul 2009
Posts: 66
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| Posted: Fri Jul 31, 2009 5:10 pm Post subject: |
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| Does Q801 have any type of internal resistor and/or diode? What type # & function is it? The part is labeled "C1685 R.72" (or could be C1885). Cannot find a datasheet on it. |
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JTS1957
Joined: 21 Jan 2009
Posts: 1331
Location: Far, Far Away
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| Posted: Sat Aug 01, 2009 3:45 am Post subject: |
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| 2SC1685 |
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chumba
Joined: 01 Jul 2009
Posts: 66
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| Posted: Mon Aug 03, 2009 8:21 am Post subject: |
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| The 2SC1685 datasheet is not showing any internal components on it, but do they always show them? Am I testing this correctly? |
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