Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: apeontheweb on January 23, 2026, 12:47:28 pm
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I built a chinese Ebay 5E3. I plugged it in and it sounded great. I smelled smoke and shut it down. The smoke came from a 4.7K voltage dropping resistor in between the first and second filter capacitors. On some schematics, it's noted as a 5K resistor. To help orient you on the schematic, it is tied to a 22K resistor I was wondering if anyone could help me troubleshoot my problem.
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My first thought is that the resistor has too low wattage. But since this is a kit... I don't know.
Have you measured current/voltage drop over the resistor (if it still measures 4.7k)?
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This layout shows it as 2 watt. I checked a Weber and Robinette layout and they're all 2 watt. You can see them on my populated, un-soldered board on the bottom left. Did they supply a lower watt resistor? Got a BOM or pics of it?
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The little bag the resistor came in said "2 Watt 47K" and I measured it and it was 47K. I don't know maybe it wasn't a 2 Watt but how would I know? The resistor still reads 47K. What voltage drop might i expect to see over it?
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The little bag the resistor came in said "2 Watt 47K" and I measured it and it was 47K. I don't know maybe it wasn't a 2 Watt but how would I know? The resistor still reads 47K. What voltage drop might i expect to see over it?
Should be 4.7K, not 47K.
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Something at that node is drawing enough current to kill that resistor. I'd be inclined to think it's the filter cap for that node, but it could be anything there.