Optocoupler in Fender tremolo

[emaxxx]

I replaced the digital LDR circuit (here in europe they ship with this http://www.bymcomunicacion.com/pvecino/pc2_.jpg) in my Deluxe Reverb with an octocoupler
I bought it locally and don't think it's oem, the tremolo hasn't much intensity and the effect isn't present until 4 or 5 on the Intensity pot.
Is there a difference between optocouplers sold by different shops and original fender part?

Thanks much,
Emanuele

[soundguruman]

The original old style is a neon light bulb and a photocell.
The LDR is not interchangeable with that.

So, it depends on which model of Deluxe you have. An old deluxe uses the neon bulb. NOT LDR.

AND there are lots of different LDRs. They are NOT interchangeable either.
BETTER to call (or email) Fender Customer service, and get the exact part number.

The OLD LDR has a number printed on it..."if" it was an LDR to start with....
IF it was a neon bulb / photocell, it's better to get the exact part from a Fender distributor.

[Pedro Vecino]

There are differences in the maximum intensity between neon / LDR cells depending on the manufacturer. Cedist cells (black with a silver dot) offer a slightly lower maximum intensity than the original Fender on the same circuit.

[soundguruman]

There are differences in the maximum intensity between neon / LDR cells depending on the manufacturer. Cedist cells (black with a silver dot) offer a slightly lower maximum intensity than the original Fender on the same circuit.

Yes there is a difference.
The neon requires about 90 volts, or a pretty fair amount, (temporarily) to glow on.
The LDR is typically 1.5 - 1.75 volts but there are a lot of variations, and special purpose ones...

Each LDR has it's own voltage, time delay spec and resistance curves. This makes it more difficult to substitute.
The neon / photocell is primitive, fairly undocumented, I love it.

[teemuk]

There are differences in the maximum intensity between neon / LDR cells depending on the manufacturer.

That, and there are several different models of "LDR". It's just as generic name for a component as a "resistor". You never buy just a "resistor", do you? There are certain finer specs that you need to care about.

Different LDR's / vactrols, for instance, have different on and off resistances and very different "saturation" characteristics, meaning they don't react instantly to their input and after being saturated - whether in dark or light - for ample period they will react even slower.

There's a very good site about the vactrol characteristics in Fender amps, and about different characteristics of possible replacements. I don't remember the site's name from top of my head but I bet Google search finds it in no time.

[Pedro Vecino]

Right. But we're talking about Neon/LDR encapsulated set provided by different companies for the same role. Same problem exists with reverb tanks depending on the brand represented with the same Accutronics code. None sounds identical.