Mastersound update
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| Posted on January 23, 2023 at 18:14:34 | ||
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Posts: 1067
Location: Florida Joined: October 17, 2003 |
Got schematics but trying to figure out power supply voltages. Most of it I can figure out except for bias, cathode resistors are 310 ohms and bias at the top of cathode resistor should be 18-20v. I might just hook up a variac and play with it but I need B+ for 300B load. All the power transformers are blown. With the bias voltage of 18v, I'm calculating about -60v at the grid with a 420v plate voltage. I'm guessing the plate voltage as well. With the plate voltage of 450v, I figured about -67v at the grid. So looking at the bias supply in my second post, does 50vac sound like a good start? The relay circuit uses a 555 timer so this is probably a 12vdc supply with about 9-10vac at the bridge. The 300B supply should be around 5vac since it does have a large 1 ohm variable dropper resistor. I can play around with this on the variac as well as the relay circuit. 
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| RE: Mastersound update, posted on January 23, 2023 at 18:16:55 | |
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Posts: 1067
Location: Florida Joined: October 17, 2003 |
Power supply 
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