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Old 1st Oct 2018, 4:00 pm   #17
ms660
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Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
Default Re: Help Identifying Capacitor

Check the value of R31 again just to be sure it's 28 ohms and not 280 ohms, if it is 28 ohms do not apply power to the receiver, the value will need to be increased to suit your mains supply voltage.

If the NTC does measure 380kohm I would say it's shot (no good) If it is shot then to give an idea as to what to replace it with it would be good to know the voltage and current rating of the lamp L1, that way we can work out what the hot resistance of the NTC should be when it's passing the designed heater current of 100mA.

C39....do you mean C49? If so the value on the schematic is given in kilo pF, eg: 22k = 22,000pF (= 0.022uf or 22nF) Replace either with an X Class type or......a polypropylene type that has at least a 1,000 volt DC rating.

The 1 meg resistor in parallel with C45....you need to keep that circuit function, the resistor will discharge C45 in the event it remains charged up to mains voltage at switch off (makes the receiver safer to work on when switched off)

220 volts versus 240 volts operation....The value of R31 can be increased to compensate for an increase in mains voltage.

Lawrence.

Last edited by ms660; 1st Oct 2018 at 4:26 pm.
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