Check the luminance/chrominance [luma/chroma] circuitry that controls the picture output in black and white and color. I would check the 3.58 MHz crystal oscillator also on the video output as well. This things help with the color processing. Usually, it is an IC or integrated circuit (could even be a flatpack) that controls this or some discreet component like a transistor, resistor, or cap. that activates the IC).
Do you really think that after over 22 years, the poster of the article to which you just replied is still waiting around for your answer?
The article to which you repled was posted April 15, 2000.
I saw the date (I can read) and I am truly sorry if my outrageously late reply deeply offends you somehow. I never expected either of us to wait and I am sure the original poster never expect me nor my specific answer to be available at any time. I posted a reply this late for archival purposes, as VCR's are outmoded now, for the most part. Besides, everyone else has had 22 years to provide some sort of answer (however simple or complex to solve the problem). Some of us when we service peoples' tech. needs are extremely busy and do not get around to writing on a forum like this. At any rate, archiving the answer is good for posterity, should anyone at any future time utilize the technology or the information and find it useful. You can perceive me as an "idiot" for the outdated response. The fact is I wanted to respond to this and thought I would offer my two cents worth (whether you value the actual input or not). The point is even though the original poster didn't wait for me or answer, somehow you did respond with a reply.
Have a great day. God Bless.
Charles Lucas
You didn't provide any specific help at all, unless you want to consider 'check the color circuitry' and 'it could be an IC, transistor, crystal, resistor, or capacitor' as helpful.
Need a model number to do that. everything is specific to the model. Also,check any and all of those things- if not sure. A good service manual for the model would help to track down the critical components that activate the circuit. There are also many different integrated circuits and circuits out there and different ways to actuate them (a resistor,a diode, a transistor, or cap, etc...), so it depends on the design of the circuit. If I have a model number, I can tell you what pins to check to verify correct operation. I have been a tech. for 32 years and not all circuits are designed the same. The initial information is generalized as a guide. If you want something more specific, please provide a model number or an FCC ID number. God Bless you.
With a problem like that, my first shot would be to sparingly, start hitting single parts in that area with cold spray, and see if the color came back. If not, then start troubleshooting. That even had success during the 1980s!
Another technique is to heat the IC up with a hot hair dryer to see if you can get it to act up that way. This worked during the 1980's also. Overheating microprocessors beyond their temperature coefficients can be dodgy... They can be tricky.
I used a soldering iron without any solder to heat individual components, hair dryers tended to heat everything up at once. That was a long time before the 1980's
Steve
Hair dryers, large heat guns, paint strippers, butane torches, and flame throwers are too large for heating individual components. Smaller is better (mini or micro heat gun):
I've also thought about building a small IR heater consisting of a hot nichrome wire and a polished aluminum reflector to concentrate the heat. Because there's no flame or blowing air, it should be able to heat individual components without also heating up everything in the vicinity. Yet another project.
The problem can be open filter capacitors in the power supply. Excessive hash on the B+ busses can kill the color circuitry.
Both of these are some of the most interesting responses I have heard. Really great replies. Thanks for the insight. I was making the suggestion I made because we found the general vicinity of the problem, then measured voltages to hone down the specific line where the culprit was.
excellent suggestions and replies. Thank you.
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