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Post by Casethecorvetteman on Mar 1, 2016 4:52:11 GMT -5
Hi all, ive just taken a measurement of the HV from the splitter where the coax connects. I have a reading of 33.35volts DC, im led to believe it should be close to 32.7volts. Can some of you take measurements and see what your machines are reading? Thanks in advance  |
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Post by dummyload on Mar 1, 2016 7:30:08 GMT -5
Be careful by adding a multimeter hv output will be higher (load multimeter on high impedant point =total impedance lower=output higher to compensate)
Adding a long wire (multimeter) to the feedback line = adding noise to the feedback line ,there is a reason they used a coax cable for the feedback signal. (don't know how you measured it,my guess)
Just saying.
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Post by Casethecorvetteman on Mar 1, 2016 7:43:15 GMT -5
There is a procedure in the SEOS diagnostics and repair manual stating that method as a suitable way to check HV output, it shows it in the pictures. They state aiming for 32.7v DC is where it should be.
The way i calculated mine from the reading was as follows:
34,700 / 32.7 = 1,061.162079510703
1,061.162079510703 x 33.35 = 35,389.75535168196
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Post by Casethecorvetteman on Mar 1, 2016 7:54:10 GMT -5
Here it is:  |
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Post by dummyload on Mar 1, 2016 8:09:56 GMT -5
O.k. had not seen this before sorry my bad , uhmm should it not stay at 34v don't get the 32,7v value.
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Post by Casethecorvetteman on Mar 1, 2016 8:18:38 GMT -5
No idea, but i assume they know what theyre talking about  |
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Post by Casethecorvetteman on Mar 1, 2016 8:19:24 GMT -5
Maybe someone with a HV probe can measure both ways and see what they get?
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Post by radiohead314 on Mar 1, 2016 10:11:13 GMT -5
One stupid question but do you know for sure you have a compatible eht quad splitter chain? Some combinations are known to oscillate or something.
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Post by dummyload on Mar 1, 2016 16:26:21 GMT -5
I also have 33,3v on the feedback point. My hv output is 33,4kv without the multimeter on the feedback point and goes up to 34,6kv when multimeter is on feedback point.(this is normal ,as expected) My 33,3v reading you can thrust but my hv value not sure I will try to check hv probe because I have the feeling my probe is a bit of. I think I know why the feedback number in the adjust manual is a lower one but I have a hard time with the explanation that the feedback value goes down when putting a multimeter on , that number should stay the same multimeter on it or not. ( ) The feedback point is the reference point for the eht board ,quad is driven by the eht board accordingly to keep the reference at the same value. So I first will try to find out if my probe is stil working correctly , we still not know exact numbers of hv according to feedback value. Anyone else can measure hv output ? . |
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Post by Casethecorvetteman on Mar 1, 2016 23:25:32 GMT -5
Yeah that would indicate that your reading is telling you that your HV level is a little bit under where it should be?
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Post by dummyload on Mar 2, 2016 3:03:25 GMT -5
Yeah it should be around 34,7kv , need some time to verify hv probe .
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Post by radiohead314 on Mar 2, 2016 8:11:01 GMT -5
33,2V
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Post by Casethecorvetteman on Mar 2, 2016 16:12:24 GMT -5
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Post by radiohead314 on Mar 2, 2016 16:30:16 GMT -5
Multimeter dc on splitter as seen on the picture you posted.
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Post by Casethecorvetteman on Mar 3, 2016 2:33:28 GMT -5
Yep, roger that. So both pretty simular to my reading.
This makes me wonder where the fault will be in these two splitters i have here that are giving focus issues.
The current splitter installed was an unknown status until i tested it, it causes the whole raster to change size occationally, which i believe means it is sending an icorrect reading back to the EHT board which is then adjusting the HV output to compensate. The raster shrinks slightly in size, which id say is due to a rise in HV.
So either the voltage sensing circuit is stuffed, or the 1megohm trim pot is varying its resistance.
The focusing issue i cant yet explain. With the R762210 splitter i had to move the yokes hard forward against the deflection yokes and midpoint setting was still down around 40 for all three tubes. Swapping focus boards had no effect on this, and all focus adjustments seem to work as they should. With the correct splitter that has the voltage varying issue, R762718, i have the focus yokes hard back against the neckboard bracket, and focus midpoint setting it still way up around 80-90 on all 3 tubes.
Initially i would suspect that voltage output with this splitter installed is quite low, based on the fact the raster was a bit larger than normal when i first installed this splitter.
So some questions and theories raised here:
Lower HV output = larger raster and high midpoint focus setting with yoke needing to be way back.
Higher HV output = smaller raster and low midpoint focus setting with yoke moved hard forward against deflection yoke.
Does anyone have any thoughts on those theories?
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