#46
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Ok I checked resistance on tubes v 2,4,6,10,11,13 all are good except v6 video output tube pins 2,3,4 should have 2k,11.5ohm,7ohm but I am getting on all 2,3 4, between 60 and 100 ohms there are differences between the 3 but amounts are high for the 7ohm and the 11.5 ohm but to low for the 2 k . the resistance numbers match the later SAMs yet the contrast is different so I'm using the ts4j late, 71 12.
Last edited by timmy; 08-02-2017 at 03:35 PM. |
#47
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I don't know but would heater voltages reflect on the drop in b+ , I ask because I can't seem to get the right ohms readings from several tubes on this set using both ts4j early and late prints along with the ts18 print all show close to the same ohms reading but I'm getting totally different readings so with the b+ down between 82-90 Vdc from 125 Vdc I'm wondering if something affecting the heater voltages if this may affect the b+ . While the 6al5 pin3 7 ohms I'm getting 22 ohms and pin 4 1 ohm I'm getting 16 ohms. V6 pin 3 11.5 ohms I'm getting 22 ohms and pin 4 , 7 ohms I'm getting 18 ohms this don't seem right yet the voltages are ok on v, 2,4,10,11,13,6. It don't make sense that b+ is so low there should be something obvious but I'm not finding it. Any help would be great at this point.
Last edited by timmy; 08-07-2017 at 08:39 AM. |
#48
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Are all tubes, including the CRT plugged in when you are making the ohms measurment? How are the ohms readings on v9 (12SN7) and v12 (12SN7)? Pins 7&8 are the heaters on the 12SN7s.
jr |
#49
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Keep in mind that the resistance of tube filament is temperature dependent. I really doubt that is the source of your problem.
Keep in mind what Tom posted earlier. B+ is created by the balance of several tubes. If it's off then either the tubes supplying current are not passing enough or the tubes drawing current are sinking too much. That could be caused by the tubes being bad or they are not biased correctly. Try swapping tube and check the voltages on them. |
#50
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Yes crt plugged in and the 2 -12sn7s, 18and16 ohms pin 8 pin 7 16and 10 ohms. The clipper is 18 ohms and 16 ohms.
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Audiokarma |
#51
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Quote:
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#52
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The tubes that supply the B+, not the tubes that are supplied by B+.
B+ is created by the drop across several tubes from the B++ supply. V1 6AG5 RF AMP V3 6AG5 3RD IF V7 6AU6 LIMITER V11B 12S7 CLIPPER |
#53
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Ok I changed the clipper tube and the b+ came up to Alittle over 100 Vdc and the verticle is good now but I'll try v,1,3,7 I tried others and I already tried v,2,4 6 .
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#54
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Ok now I tried 1,3,7 , different tubes the only one I got a positive result change from was v1 now the voltage is Alittle over 109 Vdc so that's a big improvement and the verticle is good and solid now so I'll leave it at this point. Thanks for the help guys.
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#55
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I'm glad it's working better now.
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Audiokarma |
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