EHX Frequency Analizer status LED

[Zouto]

Hi, I got an old EHX Frequency Analyzer which I modded to true bypass. Adding a status LED creates loud popping when switching on the effect. It seems to be a problem of the supply voltage for the LED, no difference in + or - 15Volts supply rail. Pulldown- resistors did not help. So any ideas what to do? Thanks a lot for help
Zouto
http://experimentalistsanonymous.com...alyzer%201.gif

[Jazz P Bass]

How about a drawing (even a crude sketch) of how you wired up the bypass & led switch?

[vintagekiki]

1)
https://www.synthxl.com/electro-harmonix-frequency-analyzer-2/

[Zouto]

How about a drawing (even a crude sketch) of how you wired up the bypass & led switch?

At the moment it is just wired for true bypass and pilot LED, I removed the 3PDT switch and status LED wiring due to popping noises when switching. Vintagekiki‘s schematic is right, thanks. The popping occurs when switching the LED to Voltage supply or to ground. The standard noiseless FX pedal wiring with status LED seems not to work poppless on this circuit....
.

[Enzo]

But the VK schematic shows none of what you added.

With your new switch in place, just disconnect the LED, does it still pop? We are blaming the LED when the problem could just be the audio switching.

[Zouto]

But the VK schematic shows none of what you added.

With your new switch in place, just disconnect the LED, does it still pop? We are blaming the LED when the problem could just be the audio switching.

At the moment just the audio switching is installed for true bypass without any popping and LED. Using a 3PDT switch for additional LED status wiring as in my regular analogue Fuzzboxes etc., the popping circus starts when switching.

[Mick Bailey]

I think the led switching may be putting a pulse onto the clean side of the regulator and being picked up by one of the ICs. Try powering the led upstream of the regulator and installing a suitable resistor - you'd need to check the unregulated voltage and work out the value.

[Zouto]

Mick, thanks a lot, that might work, I‘ll power the LED directly from bridge rectifier‘s + pole before the regulator, checking the voltage and calculating the resistor.

[Zouto]

I think the led switching may be putting a pulse onto the clean side of the regulator and being picked up by one of the ICs. Try powering the led upstream of the regulator and installing a suitable resistor - you'd need to check the unregulated voltage and work out the value.

This absolutely solved that old problem, it worked fine......nice pop-free status LED finally. THANKS MICK!!!!!!!