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Post by mastertech on Dec 2, 2013 21:01:35 GMT -5
You can measure the output of TL084 if you want but more then likely that chip is bad. After the output at that ic it goes directly to the connector edge, correct? You measured R58 already, right?
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Post by mastertech on Dec 2, 2013 21:28:55 GMT -5
If you decide to measure those G2 outputs the control voltage should change between 0-10v.
My guess is the red output is stuck at 10v. If you want to experiment and play some more you can cross the green output to the red channel and see if red goes normal. But I would not connect the red output to the green if it as at full voltage.
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nashou
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Post by nashou on Dec 2, 2013 21:32:12 GMT -5
You can measure the output of TL084 if you want but more then likely that chip is bad. After the output at that ic it goes directly to the connector edge, correct? You measured R58 already, right? Yes R58 is 1k. What about the Program not recognizing the PJ? It recognizes a PJ is connected but can not allow me to select the PJ in the list. The marquee control PJ by default selects PJ 1-8 then you select the actual PJ it turns green for on yellow for Standby and its red if Off in the program. No I noticed now by inspecting the board more closely that U31 and U32 and the decoupling caps X31,X32 had oxidation on the caps real bad and then on some of the pins for the chips, specificly bad were U31 pins 20,21,22 . Does that have anything to do with the bright red as well maybe? Software related? but first I'll swap out the TLO84 Nashou |
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nashou
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Post by nashou on Dec 2, 2013 21:41:03 GMT -5
If you decide to measure those G2 outputs the control voltage should change between 0-10v. My guess is the red output is stuck at 10v. If you want to experiment and play some more you can cross the green output to the red channel and see if red goes normal. But I would not connect the red output to the green if it as at full voltage. You were right, sorta  it was -12.75 Volts!!!! negative? R57 was 4.71 with G2 at 50. Op amp is coming out. Will report results. Nashou |
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Post by mastertech on Dec 2, 2013 21:42:15 GMT -5
I would suggest getting the red to function properly first, then a full initialize and then see if the control program functions or not. Other then verifying the red output from U103 which if it was because the G2 was to low, we have pretty much verified the bright red is because of U105. Now, could your visual findings cause a problem with the control program issue? We will have to see, after U105 is replaced. I'm done for tonight. See you tomorrow.  |
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Post by mastertech on Dec 2, 2013 21:45:44 GMT -5
This indicates that the ic probably has an internal short with the -15v supply. After you remove it do an ohm or diode test between pins 11 and 7. It will probably show a low resistance compared to (11 and 8) and (11 and 14).
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nashou
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Post by nashou on Dec 2, 2013 21:48:40 GMT -5
Thanks mac!!!! Your the Best!!! Miss you over at the other place  Nashou |
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Post by mastertech on Dec 3, 2013 9:20:11 GMT -5
Your welcome.
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nashou
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Post by nashou on Dec 3, 2013 12:48:19 GMT -5
I fixed another CLM after that one thanks to your diagnostic approach. This one had no output on any tubes. Checked the output from the OP amp and all where 0. looked at the power to U103 and no 12 volts. Pulled off the DPB and the SMD Tant for the 12 volt regulator was fried brown on one half. Replaced it with an oscon I had and all is well on that one! Nashou |
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Post by mastertech on Dec 3, 2013 13:10:16 GMT -5
Very good! Maybe you want to start going through all those problem boards you have laying around there. See how easy this stuff is.  |
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nashou
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Post by nashou on Dec 3, 2013 13:15:02 GMT -5
Very good! Maybe you want to start going through all those problem boards you have laying around there. See how easy this stuff is. I am. I have a lot of project to throw at you here. The yamaha A1 integrated with the wacky phono section. A focus board that Scott was helping me with but for some reason can't get it to work on one of the band widths And there is an adcom 6 channel amp I want to buy on ebay with a bad channel. its 145 bucks buy it now. I think I should grab it soon! I want to use it at my Diner with an adcom three zone dual tuner preamp I got( GTP 506). I just need to start them to finish them Nashou |
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