![]() ![]() If the downside voltage after diode replacement is, say, 15v high, divide that by the load current you previously calculated, and this will give you the value of the compensating resistance. You want to add additional resistance in series with the 47 ohms to make the voltage on the downside of the 47 ohm resistor the same as before. When you replace the selenium diode with a silicon one, the voltage at both the highside and lowside of the dropping resistor will go up. Divide this voltage by the resistance of the resistor, and this gives you the load current. This gives you the voltage across the resistor. With the set ON, measure the voltage on the highside and lowside of that resistor. Let's say that currently the output of the selenium rectifier goes ONLY to the 47 ohm dropping resistor, and all loads on the circuit are on the downside of that resistor. ![]() This can cause the plate voltages to "run high." I do not agree about a simple straight across replacement with no alternation in the dropping resistor. That particular player is RCA's last 45 unit ever made, and it turned out to be the worst sounding one they ever made as well. I'll never do another one of those.the speaker in those units is absolute crap, and even when the amp is recapped, it sounds like a tin can.no bass whatsoever. You position the new diode exactly the same way (the diode end with the stripe around it is the +). If you look closely at your selenium rectifier, you will see which end is the + and which is the. Come to think about it, Todd, I installed that diode in that one without any additional resistance on a small two pin terminal strip. I spent two days and almost pulled out all my hair, but I recapped that tiny amp for a customer a few months ago. I've always just installed new ones underneath. I suppose restuffing the electrolytic can would be a better choice, but I've never done that before. It's a real chore to fit three newer electrolytics under that tiny chassis, but it can be done and I've done it. I can tell you that 8EY is the hardest RCA to recap there is. You might want to touch base with Doug about what a one tube wonder might need. I know on the New Orthos (SHF-8, 9, 7-HF-5, 6-HF-5, etc.) that have the selenium rectifier, all you have to do is install the diode right in place of the selenium with no additional resistance needed. ![]()
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