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I have a Peavey Valveking 112 that has a problem with the tubes not lighting up. I've replaced D206, D207, D208, D209, but the problem still persists. Any hints or ideas? I've attached a schematic for your viewing, just in case.
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Have you tested fuse F203? Check the heater dc supply voltages. Check R213 and the solder joints of all the heater supply components. -
Why replace all those diodes?
If you have DC 30v or so at R213, then you have heater voltage. If not, find out why before replacing anything.
Remember the tube heaters are all wired in series, so if one tube is open heater or if any tube is not in the socket, NONE will light.,Education is what you're left with after you have forgotten what you have learned.Comment
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Gotcha. You're right, all the heaters on this particular model are wired in series. It was one or both of the power tubes that was causing the problem. I replaced them both and the heaters are working now. I contacted Peavey and found that this was a result of bad engineering and that one bad tube can end up taking out the others. It's working good now, thanks!!!Comment
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I don't think it is bad engineering, they designed a circuit that heats all the tubes in the amp with 900ma of current. In conventional wiring, that would take 4.5 amps of current. And then we have the circuit board connectors burning up. A technician views the schematic and knows the heaters are in series. Open heaters are not that common.Education is what you're left with after you have forgotten what you have learned.Comment
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All I know is that the designer who built that amp decided not to build it that way anymore. In most Peavey's, I usually find a bad fuse, diode, resistor, or open trace. This was the first time I found a tube causing the problem.Comment
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It is a design team of engineers. The Valve King series are wired that way, the preamp tubes in most of the high gain amps are wired that way (5150, XXX, Rockmaster preamp, Ultra, etc) Classic 30 has four power tube heaters in series and three preamp tubes separately in series on DC. Classic 50 preamp tubes are in series. They have used that arrangement for at least 25 years now.Education is what you're left with after you have forgotten what you have learned.Comment
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