HRDX footswitch troubleshooting

[pete74]

Hi all.  I've got a HRDX that works fine on it's own.  Channel/mode switching is all good.
When using the footswitch, the channel select works fine NOW....but the Drive/More Drive light is on dimly all the time and does nothing when switched other than blink when pressed.

I say channel select works fine now, as when i got it, the CR1 diode was burned out and I replaced with another.

Thoughts?

[MikeA]

If Drive/More Drive footswitch fails to change the status of the amp, check operation of S2 contacts, CR2, CR3 (3.9V Zener), CR5, and the red half of the Drive/More Drive LED.  That path switches the control voltages to change Drive/More Drive in the amp.  Unlikely to be R1.

If the Drive/More Drive foot switch actually switches the amp but it's just the Drive LED on the foot switch that's not working, check the green half of the Drive LED, and CR4.  If that's true, you'll only see red LED, not yellow (green + red.)

[pete74]

Thank you very much!

[pete74]

If Drive/More Drive footswitch fails to change the status of the amp, check operation of S2 contacts, CR2, CR3 (3.9V Zener), CR5, and the red half of the Drive/More Drive LED.  That path switches the control voltages to change Drive/More Drive in the amp.  Unlikely to be R1.

If the Drive/More Drive foot switch actually switches the amp but it's just the Drive LED on the foot switch that's not working, check the green half of the Drive LED, and CR4.  If that's true, you'll only see red LED, not yellow (green + red.)

So, to clarify my original post a bit, the drive/more drive footswitch does not change the status of the amp.   I've tested S2 and all diodes as good.  the only thing that doesn't seem to check out is the dual color led.   With my meter in diode test mode, I get a reading on one side only.  Would a bad LED in this case prevent the footswitch from changing modes on the amp?

If that is so, any idea where to source a replacement?  I've only ever seen the solid red ones available.

[MikeA]

Yes, a faulty red LED will prevent the Drive/More Drive from working.  You'll need a common cathode LED (rather than common anode), here's a 5 mm 3-color that you could use just the red and green parts of:  http://smallbear-electronics.mybigcommerce.com/led-5mm-tri-color/

And if you need a 3 mm size, here's a common cathode red-green in 3mm:  http://smallbear-electronics.mybigcommerce.com/led-3mm-bi-color-diffused/