K7000 red overdriven

darn. Checked r13, r33, r34, and r35. All were reading properly. I replaced c1, c,2, c3, and c7 and q4 even though they read good. Still have the bleeding red. I think I covered the red circuit . I could replace all the green chicklet caps like mecha suggested from a donor chassis.

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Can you see the issue with an o-scope? Choose a pattern screen that's white so all the signals should be the same and do a little bit of comparison testing. Use a 2 channel scope..
 
Can you see the issue with an o-scope? Choose a pattern screen that's white so all the signals should be the same and do a little bit of comparison testing. Use a 2 channel scope..
scopes are out of my skill range and not in my tool box. I'm usually really good troubleshooting these k7000s.
 
darn. Checked r13, r33, r34, and r35. All were reading properly. I replaced c1, c,2, c3, and c7 and q4 even though they read good. Still have the bleeding red. I think I covered the red circuit . I could replace all the green chicklet caps like mecha suggested from a donor chassis.
Also R30, 31, and 32?

How do the IC1 voltages compare with those listed in the manual? Use gray pattern to test so color signals are (should be) balanced.
 
Also R30, 31, and 32?

How do the IC1 voltages compare with those listed in the manual? Use gray pattern to test so color signals are (should be) balanced.
Ahh. I'll check the voltages late tonight to compare to the manuals voltages. I forgot to do this. I'll check r30-32 tonight as well if I haven't already.

Thank you.
 
ok here are the voltages at input and ouput legs of ic1. The video red input voltage is high like we would expect it be. 3.33 and the manual calls for 2 volts. The contrast video output pins are higher than what the manual calls for as well. Red is the highest at 3.5 and the blue and red are at around 3 volts. The manual states 1.7 R30-32 are all reading as they should.


pin 1. 3.076
pin 2. 3.3
pin 3. 2.78
pin 4. 2.68
pin 5. 2.78
pin 6. 2.69
pin 7. 2.78
pin 8. 2.78
pin 9. 1.42
pin 10.10.5
pin 11. 8.13
pin 12. 0
pin 13. .704
Pin 14. 3.74
pin 15. 11.35
pin 16. 13.03
pin 17. 2.97
pin 18. 3.0
pin 19. 3.01
pin 20. 3.1
pin 21. 3.5
pin 22. 0

 
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I'm thinking it's something before IC1 based upon that pin 2 voltage.

Are their any mods on the back side of the board at the inputs? Med res monitors (shown below) had extra resistors added on the inputs and I'm wondering if someone added one/them to compensate for the state of the board before you rebuilt it.

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Beyond that. I'd personally start swapping one component at a time from red to say green.

Otherwise just start walking backwards with a voltmeter comparing red to the 2 other channels and see if you can find the component that the differences originate at.
 
Apologies for the obvious question, but does this model not have R/G/B cutoff pots on the neckboard?

I had the same issue on my WG K7391 and a 1/4 turn on the red cutoff pot completely fixed the issue.
 

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I have the same issue but I caused mine. I accidentally connected the chassis neckboard wire back to the chassis instead of the neckboard. You know the white and blue wires? Yeah I'm an idiot. I blew r30 on the chassis. Now the red is gone unless I overdrive it. I fixed my r30and ic1. Now I'm replacing all caps from a donor chassis trying to find what else I blew.
 
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ok here are the voltages at input and ouput legs of ic1. The video red input voltage is high like we would expect it be. 3.33 and the manual calls for 2 volts. The contrast video output pins are higher than what the manual calls for as well. Red is the highest at 3.5 and the blue and red are at around 3 volts. The manual states 1.7 R30-32 are all reading as they should.


pin 1. 3.076
pin 2. 3.3
pin 3. 2.78
pin 4. 2.68
pin 5. 2.78
pin 6. 2.69
pin 7. 2.78
pin 8. 2.78
pin 9. 1.42
pin 10.10.5
pin 11. 8.13
pin 12. 0
pin 13. .704
Pin 14. 3.74
pin 15. 11.35
pin 16. 13.03
pin 17. 2.97
pin 18. 3.0
pin 19. 3.01
pin 20. 3.1
pin 21. 3.5
pin 22. 0

ic1-manual-readings.jpg
The RGB inputs (pins 2, 4, and 6) are all high.
The contrast voltage (pin 11) is controlled by the contrast pot and should vary between about 6.8V and 8.5V.
The brightness voltage (pin 14) is controlled by the brightness post and should vary between about 0 and 4.5V.
You may be able to bring the output voltages (pins 17, 19, and 21) down by lowering the contrast. This may even have some effect on the red smear, but the high RGB input voltages to IC1 are still an issue.

How do the voltages on the input transistors (Q1, 2, and 3) compare to the manual?
 
There are no mods on the bottom of the board. I went ahead and replaced every green "chiclet" capacitor on there. I replaced D5 and d6 and D7. D5 still reads differently than d6 and d7. So far that's the only thing I've been able to find that reads incorrectly in the red circuit. D5 reads like a normal diode but when I switch the leads I get an ol reading which is different than a 100% working chassis and different than d6 and d7. It's supposed to give me about a 1.9 reading when I switch the leads.
 
There are no mods on the bottom of the board. I went ahead and replaced every green "chiclet" capacitor on there. I replaced D5 and d6 and D7. D5 still reads differently than d6 and d7. So far that's the only thing I've been able to find that reads incorrectly in the red circuit. D5 reads like a normal diode but when I switch the leads I get an ol reading which is different than a 100% working chassis and different than d6 and d7. It's supposed to give me about a 1.9 reading when I switch the leads.
Normal would be OL (overload, or out of range, or open circuit). I just checked one that I have on the bench and reverse polarity reads OL on all 3 of those diodes.
 
Normal would be OL (overload, or out of range, or open circuit). I just checked one that I have on the bench and reverse polarity reads OL on all 3 of those diodes.
That's odd. Here's another working chassis and I get the 1.9 reading on reverse polarity on all 3 diodes. I get the OL reading on d5 of the "red overdriven problem chassis".
IMG-20231209-001624275.jpg
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That's odd. Here's another working chassis and I get the 1.9 reading on reverse polarity on all 3 diodes. I get the OL reading on d5 of the "red overdriven problem chassis".
View attachment 708513
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Interesting. I used a Beckman 310. I'll try to retest with a Fluke if I get the chance in the next couple of weeks. I really doubt that the diodes are your problem. Hve you been able to check the voltages on the color input transistors?
 
Interesting. I used a Beckman 310. I'll try to retest with a Fluke if I get the chance in the next couple of weeks. I really doubt that the diodes are your problem. Hve you been able to check the voltages on the color input transistors?
I'll have some me time tonight to get this one back on the bench. I guess the point I was trying to make is that the only anomaly I have found in the red circuit shows up in the d5 diode which is in indicator that I have missed the faulty component that is effecting the reading of that diode.
 
Ok . Checked the color input transistors. Q1 reads higher on the emitter than the other two. The screen I chose to display was the rbg screen with the three tall and wide colors on my tpg. That video screen also gave me the closest readings to the manual.

IMG-20231212-022644450.jpg
 
I have the same issue but I caused mine. I accidentally connected the chassis neckboard wire back to the chassis instead of the neckboard. You know the white and blue wires? Yeah I'm an idiot. I blew r30 on the chassis. Now the red is gone unless I overdrive it. I fixed my r30and ic1. Now I'm replacing all caps from a donor chassis trying to find what else I blew.
Replacing the vertical IC fixed mine.
 
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