Marshall vintage modern LED

[Simpson]

Hello,


Last saturday i got this purple amp with this purple light.
The guy was telling me that the pilot light was flickering and since then the amp was more noisy.
I have taken the light out and tested the amp, and it was sounding great, really quiet at idle.
So I have ordered a new light (like the original) from TAD.

Today I replaced the light and it seems too bright and at idle more noisy, like a buzzing noise, like power transformer buzzing and coming out through the speaker.

So i came to work thinking;
Could it be some relation between the LED and the noise?

Thanks

[Mick Bailey]

The schematic shows the LED running off the AC heater supply. The abrupt nature of an LED switching on and off with each cycle can cause noise. An AC powered LED will often look like a constant light when viewed straight on, but when you move your head you can see the flicker at half your mains supply frequency. I don't think the noise would be something that the amp suffered from when new - I can't imagine it getting past the quality checks. Is the replacement a genuine Marshall part?

[Simpson]

The part looks exactly like the original. It has one diode, (is series i think) with the LED.


Here's a link:
https://www.amprepairparts.com/mpl007.png

[vintagekiki]

Adjust the amount of light by changing the resistor R72 (68 R)

https://www.tubeampdoctor.com/en/marshall-pilot-light-lamp-marshall-vintage-modern

https://www.marshallforum.com/threads/led-power-indicator-bulb-on-the-vintage-modern.101718/

1)
http://www.marshallroadhouse.com/viewtopic.php?t=14513
Flickering Pilot Light 2266 & Other Pain-In-The-Hut Things

http://marshallroadhouse.com/viewtopic.php?t=19195
2266C Indicator Lamp out again!

[Helmholtz]

That^^
and a larger series resistor should also lower interference.

[Simpson]

i dont have the LED specs but I'm going to increase the resistor and see if the noise is related.

[Mick Bailey]

Go much larger 1st time round - If it's an effcient high brightness LED maybe between between 1.8K and 2K2. Sometimes installing a snubber capacitor across the LED can help - try 47n.

[vintagekiki]

Be sure to return the Indicator Light Clip.
https://www.amplifiedparts.com/products/indicator-light-clip-marshall-securing-lights

[Simpson]

Go much larger 1st time round - If it's an effcient high brightness LED maybe between between 1.8K and 2K2. Sometimes installing a snubber capacitor across the LED can help - try 47n.

Thanks. It's safer to go higher and start decreasing the resistance.

Be sure to return the Indicator Light Clip.

https://www.amplifiedparts.com/products/indicator-light-clip-marshall-securing-lights

I still have the original