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RCA F19207BC (CRT TV) shuts itself off even after new HOT install.

MobiusOne

Jun 8, 2022
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I have this RCA tv and since the horizontal and vertical cables are separate on the yoke the vertical works works fine but as soon as the horizontal is plugged in the TV immediately shuts itself off and I just replaced the HOT too.

The only test I did on the yoke was seek of there was continuity between two poles where the board plugs into and there was continuity on both horizonal and vertical.

Below links will contain my HOT testing
The new HOT https://imgur.com/gallery/hyyj68D
Old HOT https://imgur.com/gallery/YyhoJvD
Spare HOT I pulled from a Sansui https://imgur.com/gallery/S0LFPyh
And various pics of the components
 

kellys_eye

Jun 25, 2010
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Do you know what the coil resistance is meant to be and/or can you measure it? You could send the drive signal to a fixed resistor of a suitable value to check the deflection drive. You might have a shorted coil.
 

73's de Edd

Aug 21, 2015
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Sir MobiusOne . . . . .

He say . . . .

Do you know what the coil resistance is meant to be ?

I say . . . .
The hoz is ~3.1 ohms
The Vert is ~ 18.1 ohms


A Procedural . . . . .
Test 1 . . . .

Initial test will be having the set in totally operational condition and then unplugging it from AC power.
Then you go to the Horizontal Output Transistor area and ohm across the base to emitter of that ' 417 HOT and feed back that resistance reading.
Test 2 . . . . .
After your having confirmed the windings readings . . . and I'm expecting them to be O.K. .
Unplug the hoz connector and take your voltmeter and clip its black lead to a ground, to have your hands free. Take the meter and set to > 130 Volts D C unless its being auto ranging .
Insert the + probe into one of the removed connectors receptacles and hold there while then powering set on to see if ~ 130 VDC shows up .
If not, unplug set and wait ~ 3 min and move the + meter probe to the other untested receptacle, then plug set into line power again and turn on the set to confirm if 130 VDC is being present, this time.
Having to wait for your results now . . . . . .
EatingPopcorn.jpg


73's de Edd . . . . .

Tomorrow is National, white haired, grumpy old man Day . . . . . . . . .
and I'm totally expecting my FULL recognition !


.
 

MobiusOne

Jun 8, 2022
17
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Sir MobiusOne . . . . .

He say . . . .

Do you know what the coil resistance is meant to be ?

I say . . . .
The hoz is ~3.1 ohms
The Vert is ~ 18.1 ohms


A Procedural . . . . .
Test 1 . . . .

Initial test will be having the set in totally operational condition and then unplugging it from AC power.
Then you go to the Horizontal Output Transistor area and ohm across the base to emitter of that ' 417 HOT and feed back that resistance reading.
Test 2 . . . . .
After your having confirmed the windings readings . . . and I'm expecting them to be O.K. .
Unplug the hoz connector and take your voltmeter and clip its black lead to a ground, to have your hands free. Take the meter and set to > 130 Volts D C unless its being auto ranging .
Insert the + probe into one of the removed connectors receptacles and hold there while then powering set on to see if ~ 130 VDC shows up .
If not, unplug set and wait ~ 3 min and move the + meter probe to the other untested receptacle, then plug set into line power again and turn on the set to confirm if 130 VDC is being present, this time.
Having to wait for your results now . . . . . .
EatingPopcorn.jpg


73's de Edd . . . . .

Tomorrow is National, white haired, grumpy old man Day . . . . . . . . .
and I'm totally expecting my FULL recognition !


.
Ok, so doing that from emmiter to base gave me Zero ohms in circuit for some reason. And the voltage in test 2 was 194v and 200v.

Each probe on the horizontal plug measured different...
 

73's de Edd

Aug 21, 2015
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No response to my PM / Conversation to you for info, so I'm burning a post and re posting here.
Seems like Ruh Cee Aye made a change to your sets CTC 185 chassis and Q1114 was changed at later dates . . . .
Initially the sets Q4114 was being a bipolar # BUH517D and then later they changed it to a power FET # STP12NB30.

So o o o o inspect the chassis proper and find another heat sinked power transistor . . . .Q4114 . . . . . that is being in the same sized case profile that your HOT is in and pass on which unit yours is being .
Then I can mark up the correct schematic snippet for you and continue the quest.

73's de Edd . . . . . .
 

MobiusOne

Jun 8, 2022
17
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No response to my PM / Conversation to you for info, so I'm burning a post and re posting here.
Seems like Ruh Cee Aye made a change to your sets CTC 185 chassis and Q1114 was changed at later dates . . . .
Initially the sets Q4114 was being a bipolar # BUH517D and then later they changed it to a power FET # STP12NB30.

So o o o o inspect the chassis proper and find another heat sinked power transistor . . . .Q4114 . . . . . that is being in the same sized case profile that your HOT is in and pass on which unit yours is being .
Then I can mark up the correct schematic snippet for you and continue the quest.

73's de Edd . . . . . .
I apologize for the late reply. I was feeling under the weather as of late but I did find the chassis number and it's CTC185A
 

73's de Edd

Aug 21, 2015
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but . . .but . . .but . . .BUT . . .BUT . . . BUT . . .BUT . . . . .BUT . . . . . . . you neglecticated to check its heat sink, and see WHICH one of those two transistors, that your unit has mounted / is using .
 

MobiusOne

Jun 8, 2022
17
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but . . .but . . .but . . .BUT . . .BUT . . . BUT . . .BUT . . . . .BUT . . . . . . . you neglecticated to check its heat sink, and see WHICH one of those two transistors, that your unit has mounted / is using .
Checking that big heatsink with the vertical output and removing the support bracket shows this.

Need a bit of cleaning with alcohol
 

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73's de Edd

Aug 21, 2015
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Are the legs of Q113F (first pic) shorted? i.e. touching?
They are all bent over . . . but ARE looking adequately spaced apart . . . to my BROWN eyes . . . . . but its not being a BLUE KELLY eye.

MobiusOne . . . . .​

Before ever powering up again, be sure that the Q4114 Power FET clamping spring is back in place.

Now in using a Ohmmeter placed in low ohms and with the set cold and powered, down what is the resistance read between center pin and far right pin of that Q4114 P6H25 Power FET?


I was feeling under the weather as of late

Me TOO !
. . . I'm just coming out of my FIRST case of the full blown influenza . . .since 1972 . . . . count 'em FIFTY YEARS !
Therefore, I was re-reminded of its 6 . . . GRUELING . . . . spaced out different stages of misery.
 
Last edited:

MobiusOne

Jun 8, 2022
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Sorry for the late ness again life got to me but glad you're feeling better!
Anywho did the test on both sides. Left pin was 82.6ohms and right was 0.21!
Are the legs of Q113F (first pic) shorted? i.e. touching?
They are all bent over . . . but ARE looking adequately spaced apart . . . to my BROWN eyes . . . . . but its not being a BLUE KELLY eye.

MobiusOne . . . . .​

Before ever powering up again, be sure that the Q4114 Power FET clamping spring is back in place.

Now in using a Ohmmeter placed in low ohms and with the set cold and powered, down what is the resistance read between center pin and far right pin of that Q4114 P6H25 Power FET?


I was feeling under the weather as of late

Me TOO !
. . . I'm just coming out of my FIRST case of the full blown influenza . . .since 1972 . . . . count 'em FIFTY YEARS !
Therefore, I was re-reminded of its 6 . . . GRUELING . . . . spaced out different stages of misery.
 

73's de Edd

Aug 21, 2015
3,463
Joined
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Messages
3,463
Looking at that circuits surrounding discrete components, that LOW ohmmage is being an impossibility.
So . . . . carefully pull that transistor out off circuit / off the board and do a retest and expect the same lower reading, and then expect the need for replacing of that Q4114 item.
Its passage of more than its expected 130VDC for the HOT is a NO-NO.
DON'T then just power up after replacement . . . a SPECIAL precautionary procedure will be required.
 

MobiusOne

Jun 8, 2022
17
Joined
Jun 8, 2022
Messages
17
Looking at that circuits surrounding discrete components, that LOW ohmmage is being an impossibility.
So . . . . carefully pull that transistor out off circuit / off the board and do a retest and expect the same lower reading, and then expect the need for replacing of that Q4114 item.
Its passage of more than its expected 130VDC for the HOT is a NO-NO.
DON'T then just power up after replacement . . . a SPECIAL precautionary procedure will be required.
Sorry again for long response time had some family problems.

I did the test out of circuit with a brand-new multimeter too
 

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