Morley Optical Issue

[Jukebox_Fandango]

Hey guys,

I saw you guys had gone over a similar issue with a Morley Optical Volume in the past so I made an account to see if you could help identify the problem with mine.

Currently it does function as a volume pedal, but it cuts my raw tone down by about 20db at the max setting. It seems to be confused as to what the top volume should be. Other than that it works just fine, swelling as it should, but even at max volume through my amp my line comes through too low. Any clue what might be the issue here?

[GGBB]

Welcome to the forum. First thing we need to know is which Morley volume pedal you have. Both of mine give me unity volume at max. I suppose it could be a very slight drop but I haven't noticed that at all. Either way - far different than your experience, so yes something is wrong. They are fairly simple circuits (most models) so probably not hard to fix - it could be as simple as a bad or misaligned LED. Morley schematics for a lot of their products used to be available online from Morley but they don't seem to be anymore, although I know you can find them elsewhere including the way back machine.

[Jukebox_Fandango]

I'm not sure what you mean by which one, there's no model number to it that I can find. It's EOV so it's an LED Optical pedal, what you said about misalignment sounds like it could be the issue. I'll try opening it up and poking around.

[merlinb]

My Morley wah once burned out its own LDRs. I never did understand how it managed that!

[deadastronaut]

 Might have fluff in the led, ldr divider...

Or bend led, ldr a little...

[GGBB]

I'm not sure what you mean by which one, there's no model number to it that I can find. It's EOV so it's an LED Optical pedal, what you said about misalignment sounds like it could be the issue. I'll try opening it up and poking around.

EOV is the model. Morley has made probably a dozen or so different optical volume pedals over the years.

(If your EOV has a warranty, use it. Otherwise...)

Open it up and have a look inside. If you see any dirt or dust bunnies clean it out. Does it work yet?

The circuit is probably two LEDs that shine through slots in a card that moves with the treadle. If the LEDs look like they are not pointed relatively straight through the slots - that could be a problem. There might be only only LED, slot, and LDR - I don't know the EVO specifically.

Turn it on so you can see whether or not the LEDs are working (maybe turn off all the lights to be certain). They should both be the same brightness (probably). Find a problem yet?

The slots change size depending on the treadle position. On the other side of the slots are LDRs - one for each LED. The two LDRs form a voltage divider that is the volume control. (LDRs are resistors that change values in response to light.) Both should have the same value given the same amount of light - and that can be extremely high. Measure yours - with the power off in the dark, with the power off under room light, with the power on in the dark and the treadle at min and max position plus in between (say 25%, 50%, and 75%).

Post your findings back here along with a picture of the inside of your pedal.

If you do play around with the position of the LEDs, keep in mind that this can change the taper of the volume adjustment. It won't break anything really, but it might change how it "feels" to you. You can always play around a bit more to adjust the feel of the taper (Morley actually promotes that).

[PRR]

> If you see any dirt or dust bunnies clean it out. Does it work yet?

I have optical mice on my PC and hairy dogs on my floor. Your advice is wise.