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Post by mastertech on Nov 19, 2016 21:57:55 GMT -5
How about voltage on both sides of R115 and R116.
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nashou
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Post by nashou on Nov 19, 2016 22:02:59 GMT -5
How about voltage on both sides of R115 and R116. -7.2x and -14.2x on both sides pretty close for each. nashou |
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Post by mastertech on Nov 19, 2016 22:04:52 GMT -5
Ok and how about those caps you brought up before C123 and c124. Voltage both sides.
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nashou
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Post by nashou on Nov 19, 2016 22:05:36 GMT -5
seems like everything is close. Could there be a part that only shows fault when first turned on then settles down once its been on for a few seconds. The initial
curent rush makes it through to TR107 and blows it?
Nashou
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nashou
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Post by nashou on Nov 19, 2016 22:09:03 GMT -5
Ok and how about those caps you brought up before C123 and c124. Voltage both sides. C123 + side -24.42 - side -6.74 C124 + Side -24.41 - Side -8.35 |
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Post by mastertech on Nov 19, 2016 22:12:42 GMT -5
Well this is something. They should be the same, not opposite. let me look some more. They are definitely opposite?
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nashou
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Post by nashou on Nov 19, 2016 22:14:16 GMT -5
Well this is something. They should be the same, not opposite. let me look some more. They are definitely opposite? oops they are all Negative Sorry getting tired. |
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nashou
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Post by nashou on Nov 19, 2016 22:27:31 GMT -5
Off to bed , work at 5:30 am !
Thanks Mac this one is a real pain !
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Post by mastertech on Nov 21, 2016 20:18:04 GMT -5
I think the next time you put this channel back together you should remove R137 before firing it up to test. I believe this is where TR107 keeps getting blown up. If there is any voltage on the preamp line it will go through here and back to the JFET on the tr105 side.
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nashou
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Post by nashou on Nov 21, 2016 21:36:22 GMT -5
I think the next time you put this channel back together you should remove R137 before firing it up to test. I believe this is where TR107 keeps getting blown up. If there is any voltage on the preamp line it will go through here and back to the JFET on the tr105 side. Right, I just noticed something. Tr119 and 120 get really really hot. Almost too hot to touch for a long time. I touch all other transistors and they just get warm. I think TR119 a bit more tho. Hard to tell for sure as they are right next to each other. I also noticed that C127 and C128 on the schematic are 4.7uf 50v but on the board they are 22uf 50v. Not sure if that would cause an issue or not. Just measured that area with a thermal gun, 82 cecius!!! Nashou |
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nashou
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Post by nashou on Nov 21, 2016 21:54:46 GMT -5
You can see the darkened PCB.  |
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Post by mastertech on Nov 21, 2016 22:16:26 GMT -5
If you look under the parts list, C127 and C128 calls for 22uf/50v so I would say they are correct. As far as TR119 and TR120 they are part of the servo amp which applies to the rail lines for both channels. They may normally run hot or because the circuits are not running properly yet. But they are not tied to just 1 channel.
Do you have enough parts to populate TR107 and that channel completely, remove R137 and test for any voltage on R153?
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nashou
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Post by nashou on Nov 21, 2016 22:25:09 GMT -5
If you look under the parts list, C127 and C128 calls for 22uf/50v so I would say they are correct. As far as TR119 and TR120 they are part of the servo amp which applies to the rail lines for both channels. They may normally run hot or because the circuits are not running properly yet. But they are not tied to just 1 channel. Do you have enough parts to populate TR107 and that channel completely, remove R137 and test for any voltage on R153? Understood, Just found another bad part. Not sure how I missed it before but D 104 was bad. With this new info how should we proceed? I have three 2SK363's , so yes i can repopulate that channel. Nashou |
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Post by mastertech on Nov 21, 2016 22:30:17 GMT -5
D104 could of been the problem but I would still remove R137 for testing to see if the channel is balanced.
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Post by mastertech on Nov 21, 2016 22:30:53 GMT -5
With TR107 populated.
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