Quote:
Originally Posted by TinCanAlley
There are five boards press fitted on the chassis. I have removed each one, cleaned them, their contacts and reseated them. No effect.
If I crank up the contrast, the dark bars get lighter until the match the existing lighter bars. So if I crank it up, the entire screens becomes over saturated and it's pretty hard to see the bars (pretty sure they're still there).
Should I be looking for ground points only in the horizontal circuit? It's pretty crazy trying to find out all the ground points on all the terminal strips and such. Only the ground points of the modules are noted. All others have to be located manually. Not an easy process.
I'm going to replace the voltage divider as the current only is leaking. On humid days it buzzes and has a blue corona. If you put your finger near it, it tries to reach out and touch you. Could this cause the moire?
I believe the scope I am using goes up to 500 kHz. I also got a new x10 probe. I just have to figure out what ringing would look like when comparing the wave I get to the one in the SM.
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Not sure what you mean by "saturating?" Do you mean the whole picture gets brighter? Does the bar pattern stay visible if you crank up the contrast AND turn down the brightness (to prevent "saturating")?
My suggestion is to try connecting known ground points directly to where they are supposed to go in case the connectors on the PC boards are still not making good contact even though you cleaned them. Also, you can try connecting different ground points on the PC board connectors to each other to see if that helps.
What is the maximum gain (volts/division) that your scope has? Depending on where in the circuit, you may need more gain than your scope provides to see this waveform, especially if you use a 10x probe.
Your scope needs to be synced to the horizontal sweep. If you cannot sync it independent of the probe input, it will be next to impossible to trace the waveform. You definitely then need a better scope. If the scope is locked to horizontal sweep and showing at least one complete sweep cycle, the jail bars will appear as a sine wave of decreasing amplitude from left to right, with about 10 or 12 cycles within one horizontal sweep (as you can count by looking at the TV screen). This decaying sine wave will be added on top of whatever normal waveform is at the place you are probing.