M49c(ac701k tube) PSU reads 35v???

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distorter

Well-known member
Joined
Mar 23, 2022
Messages
47
Location
Nanjing
Hi guys, may I ask a stupid question?
Today, out of curiosity, I tried to measure the power supply(NN 48U) for ac701k heater(which should be 3.8-4v), my multimeter read 35v…

The PSU drives my M49c perfectly. So I am wondering, is the 35v reading right? Why it reads 35v?

Thanks in advance if anyone could share some information!
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distorter

Well-known member
Joined
Mar 23, 2022
Messages
47
Location
Nanjing
Tough (or nearly impossible) to say, without seeing a schematic.
It is a NN 48 u, so it is similar to a NN 48 a. I think the aging is causing the high voltage.
Is it possible to place a 2 Ohm dropping voltage resistor before the connector?
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