Riddled TV Repair Forum

troubleshootn · Joined: 24 Feb 2009 Posts: 6 Location: hickory nc

1993 hitachi 46ex3b projection

I hit the power button the relay clicks on supplys voltage all across the board, it checks at 120 volts at the first set of fuses drops to 65volts at sum type of resistor, then drops to 35 volts on pretty much the rest of the board. There is 35 volts on all the crt 's with power on, i checked the voltage at iso901 STR-M6511 its at 65 volts I was told this could be a possible problem, but I have no idea what test is needed to check the part or if this is even the problem???? Has anyone ran into this problem im sure it is simple, but my limited knowledge in the area is not helping.

Any help would be great.

Thanks Caleb

Google

JTS1957 · Joined: 21 Jan 2009 Posts: 1387 Location: Far, Far Away

Let's hope you're referencing the "correct" ground for the different points you are measuring (Hot/Cold).

troubleshootn · Joined: 24 Feb 2009 Posts: 6 Location: hickory nc

Ok this will prob show my ignorance, but all grounds were checked at the power leads coming into the board, I grounded my tester at the neg of the wall plug coming into the board, then checked voltage on all kinds of places have no clue what Im doing. I was more hoping someone knew of a tsb or related problem who may have an answer or at least tell me which direction to head in???? But from the power source to most of the board is 35 volts

JTS1957 · Joined: 21 Jan 2009 Posts: 1387 Location: Far, Far Away

The "Primary" of the set's Switched Mode Power Supply (SMPS) uses a "Hot" ground reference (i.e. main filter "-" / Raw B-Plus Bridge rectifier "-").
The secondary of the SMPS uses a "Cold" ground as its reference (i.e. Tuner cover).
If you try to measure a point in the set that is supposed to be referenced from a Cold ground from a Hot ground instead, you will get a erroneous reading.

troubleshootn · Joined: 24 Feb 2009 Posts: 6 Location: hickory nc

Ok makes sense, but getting back to my original problem what are some possible causes for the symptoms My set is having??

Hit the power button hear the relay click once but does not turn on??

I obviously have power throughout the board so what gives???

Something isnt turning the crts on???

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kuhurdler · Joined: 28 Dec 2006 Posts: 2582 Location: Overland Park, KS

This may upset you. But I'll say it anyway.

I stopped reading your first post when I couldn't understand through all the run-on sentences. You should try to make it easy for people to help you.

JTS1957 · Joined: 21 Jan 2009 Posts: 1387 Location: Far, Far Away

Since this is now your second thread about the SAME television, did you ever try changing the regulator (STR-M6511) as was previously suggested?

troubleshootn · Joined: 24 Feb 2009 Posts: 6 Location: hickory nc

Maybe if I talk in Robot it would help.

Reg did nothing

Jesse Mack · Joined: 22 May 2008 Posts: 600 Location: The Last Frontier

Hi Caleb,

Yes, ROBOT would help. After all, Is not help what you are asking for?? (:>)

These are the parts of concern:

Q902: Part number 2323782 SCR (Silicon Controlled Rectifier)
CP902: Part number 2793312 Caprister
IC901: Part number 2373343 Regulator
ZD904: Part number 2334304 Zener Diode
R922: Part number 0700023 Resistor (47 Ohm 1/16Watt Carbon)

All except resistor is available here: http://www.encompassparts.com

You should be able to acquire the resistor from Radio Shack

Smile Caleb, If you do not know what some of these things are, at least know that one of these things are what has most likely failed for this chassis.

Hope this helps

Jesse

kuhurdler · Joined: 28 Dec 2006 Posts: 2582 Location: Overland Park, KS