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Post by gjaky on Feb 28, 2016 3:26:51 GMT -5
I would not try to measure the feedback line its high impedance ,so putting a meter (load) on it will change hv output ,and you probably at noise to it to ,and the 1/1000 resistor divider can be the problem ,so only measuring the hv output can give you valid level of the hv . Image pulsing in and out have had that to in a barco data600 =faulty splitter= hv goes up and down , I would like to know if its the c on output thats dying or the divier thats dying ,the divider is very simple but if you do the math you quickly find out that doing it with a low dissipation you get very high impedances . (347megohms dissipates 3,47wat at 34,7kv) What is the value of that trimmer pot? |
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Post by radiohead314 on Feb 28, 2016 6:18:20 GMT -5
I think there is a listed procedure for it in a SEOS manual, GregSTV recently forwarded it to me, and i passed it on for upload here. Either way im not overy interested in testing that side of it, but i would like to test and adjust the EHT board settings, ill have to grab a HV probe for my Brymen meter. In the 909 service manual under the EHT you can read how to adjust the two potmeters on the EHT. But you need a 1000x hv probe. Perhaps you can borrow one? P1 High Voltage Adj. P2 Hold Down - Switch off the projector - Put the fuse 2A on its place. - Switch on the projector - Adjust potentiometer P1 "High Voltage Adj." until the EHT voltage reaches 36.5kV. - Turn potentiometer P2 "Hold Down" until the Hold Down LED lights up. The projector switches at that moment into the Hold Down mode, picture disapears. - Put the potentiometer P1again in its minimum position (turning clockwise!!). - Turn the power switch in its OFF position (not-pressed) and switch on the projector again (press the power switch). - Adjust the potentiometer P1 for an EHT voltage of 34.7kV. Important: The EHTsplitter, on which a potentiometer is mounted , leaves the factory as a factory pre-adjusted unit. A readjustment of the mentionned potentiometer is in no case allowed. |
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Post by radiohead314 on Feb 28, 2016 6:31:19 GMT -5
I would not try to measure the feedback line its high impedance ,so putting a meter (load) on it will change hv output ,and you probably at noise to it to ,and the 1/1000 resistor divider can be the problem ,so only measuring the hv output can give you valid level of the hv . Image pulsing in and out have had that to in a barco data600 =faulty splitter= hv goes up and down , I would like to know if its the c on output thats dying or the divier thats dying ,the divider is very simple but if you do the math you quickly find out that doing it with a low dissipation you get very high impedances . (347megohms dissipates 3,47wat at 34,7kv) What is the value of that trimmer pot? For the curious like me here are some pics. Trimmer says 1M. The colour codes should give the values. There seems to be 320MOhm internal in the switcher.  Untitled by Radio Head, on Flickr red purple green and the gold 2700k  Untitled by Radio Head, on Flickr green blue yellow and gold 560k  Untitled by Radio Head, on Flickr |
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Post by Casethecorvetteman on Feb 28, 2016 7:29:45 GMT -5
What is the value of that trimmer pot? For the curious like me here are some pics. Trimmer says 1M. The colour codes should give the values. There seems to be 320MOhm internal in the switcher. Untitled by Radio Head, on Flickr red purple green and the gold 2700k Untitled by Radio Head, on Flickr green blue yellow and gold 560k Untitled by Radio Head, on Flickr Yeah ive got that procedure here thanks, but i need an extender board to do the adjustments so i found out. |
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Post by gregstv on Feb 29, 2016 2:10:39 GMT -5
What is the value of that trimmer pot? For the curious like me here are some pics. Trimmer says 1M. The colour codes should give the values. There seems to be 320MOhm internal in the switcher. Untitled by Radio Head, on Flickr red purple green and the gold 2700k Untitled by Radio Head, on Flickr green blue yellow and gold 560k Untitled by Radio Head, on Flickr Red Purple green would be 2.7meg ohm not 2700k |
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Post by radiohead314 on Feb 29, 2016 4:57:58 GMT -5
He 1000k is 1Meg
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Post by Casethecorvetteman on Feb 29, 2016 7:43:19 GMT -5
Yes it is.
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Post by Casethecorvetteman on Feb 29, 2016 7:59:38 GMT -5
So based on numbers if taken from the two different splitter part numbers i have here, id have to assume that the one with 3nF and 25k ohm was the cause of the vastly different focus numbers i was seeing while it was installed.
The focus yokes were pushed as far forward as possible and the midpoint numbers were around 40, all 3 tubes were affected in the same way, swapping focus boards made no difference. When the correct splitter is installed the midpoint is set to 57 and the yokes are moved to give best focus, which is about mid way between the deflection yoke and the neckboard bracket.
Having said that, the R762210 splitter worked for a long time without issue, but i always felt the focus was never as sharp as it should have been in the midpoint, however some zones could be made slightly better than others. The lack of sharpness was something i put down to the massive amount of hours on the tubes, because it did take a slight hit when i swapped them in for the original 7,500 hour tubes that showed alot more phosphor wear. The splitter was also swapped out when the tubes were swapped, so there is a good chance it was that all along.
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Post by Casethecorvetteman on Feb 29, 2016 8:08:14 GMT -5
Id say though the R762210 splitter could be used if indeed the EHT board was correctly calibrated to suit the different output that would likely be seen at the anodes, but without testing that i really cant be sure.
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