5k to 8 ohm POTs
 

My TV needs new POTs for it's CRT's R, G, and B BIAS.

I was scratching my head, because I thought I was seriously getting over-corrective with color balance for the past few months. I know that my eyes will lie to me about color when I enter the room, but it's colors were just SO far off, that I had a feeling something was up.

So today I tried something. TV off, and ohm-metered all 3 POT's, two of them, blue and green, are NOT steady, and constantly through measurement would just flicker between ohms. No wonder I kept seeing odd colors!!

But these POTs are quite different, I haven't found a direct replacement yet.

Bad view, but these are the POTs.

http://img.photobucket.com/albums/v3...n/tvboard1.jpg

Perhaps there's a direct replacement for these.

What is the needed resistance value? Remove one of them from the board, and measure the value of the element from end to end. No connection to the wiper needed for this test.

The pots don't look like anything special, just standard cheapo trimpots. Should be able to get something similar from most any parts supplier. If you are a real stickler for tweaking the color balance, you might want to swap in multi-turn trimpots for finer adjustment. :D

im sure i have good used ones off a board i have striped if interested i could look ,before you replace them have you tried to spraying them out with contact cleaner and them compressed air ,for all three in a row to be bad sounds like they could just be dirty.

No, haven't tried cleaning them yet. I'm usually weary of spraying any liquid on electronics. But I could try it.

As for the resistance, the SAMs shows 5k to 8 ohms, like the title of the post.

I really am, especially now that I'm the proud owner of a colorimeter probe.

This TV has already been calibrated, but due to these POTs, it's lost it. So it needs to be done again already.

That isn't really a standard way of specifying a pot, FWIW.

Usually, only the total resistance of the element is given, which sounds like it might be 5K. The minimum resistance is understood to be near zero, when the wiper is at the end of travel.

Are these 3-terminal devices (potentiometers) or do they have only 2 terminals (rheostats)?

If you want to go with multi-turn trimmers, check out this page:

http://www.surplussales.com/potentio...ltiTurn-8.html

3 pin.

By the way, thank you for this link. This is probably the best thing since sliced bread.

Any wattage should work, right?

Those little trimpots aren't going to be good for more than a half watt or so, so anything more than that should be fine.