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#10
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Hey guys,
I just got done taking voltage readings of all the IF stage transistors, the Video Amp transistor, and the Video Output transistor and found some interesting results (especially the video out transistor...) Here are the readings in order of what's specified on SAMS and what I read with my multimeter. Supply Voltages: -5v -- reads -4.4v +11v -- reads +8.2v -11v -- reads -8.8v First IF Transistor (X1) Base -- 1.5v -- reads 0.85v Collector -- 0v -- reads 0v Emitter -- 2v -- reads 1.22v Second IF Transistor (X2) Base -- 2.0v -- reads 1.27v Collector -- 0v -- reads 0v Emitter -- 2.2v -- reads 1.57v Third IF Transistor (X3) Base -- 8.5v -- reads 6.62v Collector -- 0v -- reads 0v Emitter -- 8.6v -- reads 6.77v Fourth IF Transistor (X4) Base -- 8.5v -- reads 6.37v Collector -- 0v -- reads 0v Emitter -- 8.6v -- reads 6.58v Video Amp Transistor (X5) Base -- 10v -- reads 7.28v Collector -- 4v -- reads 2.84v Emitter -- 9v -- reads 7.5v Video Output Transistor (X6) -- here is where the problem is... Base -- 9v -- reads 6.65v Collector -- 9.5v -- reads -8.66v (!) Emitter -- 0.5v -- reads 8.11v (!) Could it be a bad Video Output transistor? I haven't replaced any of the diodes, which are the original 1N60A germanium diodes -- these seem pretty common and I can replace them if you think it'll help. What do you guys think about these readings? If you missed the schematic, I included it in a previous post. Thanks again for your help! Last edited by goat1981; 10-07-2015 at 10:20 PM. |
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