| Electronics > Beginners |
| Identifing a Potentiometer |
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| SuperDaveOsbourne:
Did email him last week with no response. I did download the video and try to do screen grabs but there just isn't enough resolution at 720 to get much. What I do know is that any of the stuff not on the main board or display board isn't on the parts list. I am replacing the 2000uf and the 1000uf back on the power supply and they aren't in the manual/parts list or schematic he showed, at least that I could see. He said forcefully he would not scan the manual or the schematic in the video and not to ask. I just asked if he would let me the know the value. From the parts list I try and eliminate all the "controls" as they call them. It leaves me with 500k and a 100k which might just be some rework on the board. Sencore emailed me back that they don't have any manuals or parts and they are out of that business. At least for the CA55, might have other stuff. |
| Jwillis:
--- Quote from: drussell on August 25, 2018, 08:08:51 pm --- --- Quote from: Jwillis on August 25, 2018, 07:51:48 pm ---Take a measure from center to 1 quarter of just the carbon track and multiply by 4 that will give you a ball park measurement . Judging from the number and description it's a 16mm 1/8 shaft 15K linear. 15K seems odd ,but try the measurement to see what you get. --- End quote --- Once again, the OP stated that the carbon track is damaged (the carbon layer is gone), so he cannot measure it: --- Quote from: SuperDaveOsbourne on August 25, 2018, 04:28:35 pm ---You can see in the picture that the resistive carbon had all come off. The flakes on the paper towel of what was left and there was no continuity anywhere across the graphite ring. --- End quote --- --- End quote --- From the appearance of the photo some of the track is still in place only the to ends are broken free so check the unbroken part like I described in previous post .By appearances theirs not enough carbon flake on the towel to make up a whole track.If indeed the whole track is missing then your S.O.L. |
| Brumby:
--- Quote from: Jwillis on August 25, 2018, 11:55:51 pm ---From the appearance of the photo some of the track is still in place only the to ends are broken free so check the unbroken part like I described in previous post .By appearances theirs not enough carbon flake on the towel to make up a whole track.If indeed the whole track is missing then your S.O.L. --- End quote --- I was thinking the same thing and enhanced the photo a bit for a better look: My annotations are just a guess, but it seems like there might be a chance that the section to the right (between the two yellow lines) is intact. If that is the case, then do a resistance measurement at the point of those yellow lines. Since those lines represent about half the rotation of the pot, just double that measurement to give you a pretty close value for the pot - presuming it is linear. If this section of the track is good, you can verify it as a linear taper by checking the resistance from each yellow marker to the green one - and they should be roughly the same. |
| SuperDaveOsbourne:
The most resistance from any two points I could get was 5 ohms. |
| Brumby:
.... on the black carbon track? :-// |
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