Toshiba 27A45 TV will not turn on

jts1957 · Joined: 24 Nov 2008 Posts: 2476 Location: Far, Far Away

155 volts is your Raw B-Plus, or rectified mains, as Pentode pointed out.

I've been trying to have kramden66 proceed in a logical manner, but it appeared he didn't want to cooperate.

So, to continue....
Next we will see if you have ANY secondary voltages from the switched mode power supply (SMPS).
Measure across C527 - should be approximately 13 VDC (volts DC);
Measure across C521 - should be approx. 115 VDC;
Measure across C501 - should be approx. 16.5 VDC.

IF THESE ARE ALL PRESENT you don't have to worry about Q502 working;
If these are NOT present, we will be going to Q502 next.

Let me know the results either way.
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kramden66 · Guest

S/C line ? if i checked the transistor on the heat sink and its bad then its probably whats wrong but time has slowed me down on this so i can only do a little here and there

mike

jts1957 · Joined: 24 Nov 2008 Posts: 2476 Location: Far, Far Away

s/c = short circuit horizontal output (or Zenith "Space Command"). Wink

Sorry for multiple post. 7:40 post has rare "edit" button, but not this one.
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Guest · Posted: Fri Sep 03, 2010 7:08 am Post subject:

jts1957 i haven't been ignoring you i've just been mentioning ideas of what might be wrong , when i can i will check the voltages on the capacitors you mentioned, time has not allowed me to do much with the set , so probably Saturday i will be able to read the voltages
thanks so much for your help
Mike

minnie · Joined: 18 Aug 2005 Posts: 2880 Location: Hell

Q502 is known to go bad it's a 2sk3326.

kramden66 · Guest

There is no voltage on these capacitors , well theres less then 1 volt it seems on c501 but tripple checked these electrolytics and theres no voltage , So what to do next? that q502 ?

Mike

jts1957 · Joined: 24 Nov 2008 Posts: 2476 Location: Far, Far Away

Affirmative.

IF Q502 does not test good, especially if you obtain any shorted readings, I would suggest testing (in no particular order) R542; D507; R544; D523; R502; Q514.
IF Q514 checks bad: R545; D524; D509; R508; D506 & IC504.

Report which item(s) bad and whether open, shorted, leaky, etc.
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kramden66 · Guest

I haven't had any time to work on this but had a few minutes and decided to check all the resistors and diodes that you listed and they all check ok , so now i have to remove the 2sk3326 transistor to check it unless i can check it in circut ? , i currently do not have a transitor tester so my question is can i check it with the ohms or diodes settings ?

Mike

jts1957 · Joined: 24 Nov 2008 Posts: 2476 Location: Far, Far Away

http://wiki.answers.com/Q/How_you_check_whether_mosfet_is_working_or_not
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Guest · Posted: Mon Oct 04, 2010 8:31 pm Post subject:

its been a while but i finally sat down and checked this transistor , it reads likethe link says it should with mega ohms on s and g also g and d , the diode measurement shows good one way and open just like in the link , so the question is now what ? i think everythings been checked except Q 514

Sorry that i haven't been able to get around to this sooner

thanks
MIKE