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Old 15th November 2014, 10:28 AM
John Caswell John Caswell is offline
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Join Date: Dec 2005
Location: Wokingham, Berkshire
Posts: 1,674
Default Re: Help - Phono 3 Heater voltage Measurements

Hi
What you are describing does not make sense.
If the readings on the socket on the back of the Phono III are correct i.e. 53V and 60V DC then as you only have two wires grey and brown going from the socket to the PCB heater +/- and you say that the heater volts are correct on the heater pins then I suggest that you are measuring incorrectly.
I assume that you are measuring this with the DMM set to 200V DC and not AC (which will give all sorts of strange readings.)
I also assume that you have definitely got the earth pins on the PCB returning to the earth pin on the main smoothing capacitor in the phono III.
Initially I suggest the you switch off, remove the umbilical and all phono III valves and measure continuity across the heater +/- pins on the PCB. It should read open circuit, plug one valve in and the reading should drop to a low figure indicating that the heater wires are continuous (which they must be as you say the Phono III is working OK.
Have a look/check and report back.

John
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