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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment.

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Old 10th Oct 2019, 11:04 am   #1
Eagles123
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Default How to fit a pilot light to a Philips NG5155 amplifier?

Hi all,
Long time lurker, first time poster here.

So, I aquired a NG5155 valve record player. All working fine, the electrics had all been modernised with new resistors and capacitors etc but the casing and turntable was damaged beyond repair.

I removed the electrical section and will rehouse and adapt it to use as an mp3/turntable amplifier.

The original record player never had a bulb to show whether it was on or off - I would like to fit one, but am unsure the easiest and safest way to do it.

I was thinking of using the on/off switch pot lugs to attach it to - am I on the right lines ?

I think I'd rather have a bulb with 'jewel cover' unit (like a guitar amp) than an LED.

Any help would be gratefully appreciated, thanks
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Old 10th Oct 2019, 11:21 am   #2
AC/HL
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Default Re: How to fit a pilot light to a Philips NG5155 amplifier?

The safest way would be to use a 6.3v filament bulb wired across the valve heaters, but a mains neon as you suggest will be OK.
THe circuit is the same as the NG5055: https://www.service-data.com/section.php/6168/1/ng5055
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Old 10th Oct 2019, 2:15 pm   #3
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Default Re: How to fit a pilot light to a Philips NG5155 amplifier?

Some odd "Philipsisms" in the amplifier- volume controls have some odd frequency shaping and whilst there're bias resistors for each output valve, they're in parallel with a single bypass capacitor

Maybe two small resistors were cheaper than one big one?
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Old 10th Oct 2019, 2:35 pm   #4
Oldcodger
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Default Re: How to fit a pilot light to a Philips NG5155 amplifier?

Quote:
Originally Posted by AC/HL View Post
The safest way would be to use a 6.3v filament bulb wired across the valve heaters, but a mains neon as you suggest will be OK.
THe circuit is the same as the NG5055: https://www.service-data.com/section.php/6168/1/ng5055
Not exactly in keeping with old practices, but a novel way of providing an on/off indication if it does not look out of place is to use a LED with a reverse diode and a capacitor to drop volts. But if using a 6v hater supply I'd use a reverse diode on the LED and a 600 ohm 1/4 watt resistor ( IF my maths are right), as using the standard method of using a capacitor would need one circa 5F. Where as ( again if my maths are right, using a cap and mains would need a 0.5 uF cap).
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Old 10th Oct 2019, 5:27 pm   #5
AC/HL
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Default Re: How to fit a pilot light to a Philips NG5155 amplifier?

The OP doesn't want an LED though.
Item 3 here is the classic: https://mullard.org/collections/comp...-lights/bulgin
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Old 14th Oct 2019, 12:36 am   #6
Eagles123
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Default Re: How to fit a pilot light to a Philips NG5155 amplifier?

Hi there,
Apologies for not getting back sooner. Thank you all for the help and information, it
was greatly appreciated.
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