New "vibrato optocoupler" from Fender

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New "vibrato optocoupler" from Fender

Postby Sterling on Fri Feb 22, 2008 10:03 am

Hello. I have discovered in two Deluxe reverb reissue (bought today) a strange and complex circuit that replaces the cell neon/ldr in vibrato circuit.
The basic vibrato circuit in the board is identical and all this matter is to only replace the cell neon/ldr.
The system works worse than the traditional one, generating in addition background noise non-existent previously.
From this moment is very possible that all Twin Reverbs, Deluxe Reverbs, Super reverbs incorporate it.

Image

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The new pcbs already retired:

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From the mains transformer AC line for bias and vibrato goes directly to the new PCB and from there it comes back to the general PCB (two original red cables in reissue model).
I have removed the new circuit and installed a classic optocoupler and the circuit works like always and without noises.
All that does not make sense and it is possible that it has relation with the ROHS norm.
Another innovation that has is the incorporation of extra resistors in 12Ax7 grids (apart from the typical ones of 68K in the inputs) to contain the noise produced by the modulation. Once transformed the circuit they are not necessary

The same message I put it in Ampage and in Guitarramania (spanish forum). I have thought that it is possible to be interesting to put it here. Sorry for my poor languaje
Regards
Sterling
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Postby Vortexion on Fri Feb 22, 2008 1:52 pm

No need to apologise for your words - we can read you fine, Sterling.

That certainly is one hell of a lot of....JUNK....to put in place of a simple electro-optical device. I bet you're right, too. It will have been introduced to fit in with ROHS legislation and make life easier for the manufacturer - and to hell with the sound quality! :roll:
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Postby PeterS on Fri Feb 22, 2008 3:08 pm

Maybe it's cheaper than the optocoupler, despite the higher parts count.
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Postby PeterS on Fri Feb 22, 2008 5:26 pm

Maybe it's cheaper than the optocoupler, despite the higher parts count.
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Postby Vortexion on Fri Feb 22, 2008 6:13 pm

A double-post, 2 hours and 18 minutes apart - weird! :?
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Re: New "vibrato optocoupler" from Fender

Postby Petesdvd on Tue Oct 16, 2012 1:20 pm

Hi all! I am new to this but i noticed i got an DRR like this. I really want to throw this out and put in an optocoupler instead.

My question is,

1.do i need to reattach some cables after i ripped it out?
2. How to fit the optocoupler? are the pins marked which side are the photoresistor?

/Pete
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Re: New "vibrato optocoupler" from Fender

Postby PeterS on Thu Oct 18, 2012 2:30 am

I often get a laugh out of these zombie threads, I read the first post, think of a reply, and then discover - ha - some idiot already said that - and the idiot was me!
Sorry, don't know the answer to your question -- but you can tell which end of the optocoupler is which by looking in it.
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Re: New "vibrato optocoupler" from Fender

Postby emaxxx on Tue Apr 29, 2014 9:47 pm

I bought few days ago a 68 Custom Deluxe Reverb and I have the same issue...the optocoupler is replaced with a pcb. The amps suffers from high background noise even at low volumes (i think probably worsen cause of the grid resistors). I was planning to replace it with the correct optocoupler and I ask you if you can help me and remember the connections and what to get away from the circuit especially extra resistors. I have fear to make a mess. It's a little bit difficult find info about this problem cause it's only present in european amps.
Hope you can help.
Thanks much,
Emanuele
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