Fender Deluxe Reverb II

[pnut5150]

I have a deluxe reverb II here, channel 2 only produces a very low output unless you pull the instrument cable out a little bit..any ideas? and how do you test a LDR?

https://www.thetubestore.com/lib/the...-Schematic.pdf

[xtian]

So...you manipulate the instrument cable a certain way, and it works fine? Bad cable or input jack. Your issue seems pretty localized to me, unless I'm misunderstanding you. Both of those input jacks have two normally closed switches each--those things get dirty and fail to close completely. Can you get some DeOxIt into the contact points?

[pnut5150]

Brand new cable works great in other amps, does same thing in both jacks. I have sprayed DeOxit in both jacks. Owner of amp says it worked and suddenly stopped.

[Randall]

First thing is to re-solder the connections on both input jacks. This isn't complicated.

[pnut5150]

I’ll solder them, I just don’t really see both of them doing the same thing at the same time.

[xtian]

I've met certain 1/4" plugs that are just barely out of spec--work fine mostly, but cause issues in the rare input jack. Try another cable!

[pnut5150]

Yea already did that, that’s what my buddy had me looking at it for also. Doing the same thing with him.

[Justin Thomas]

But both jacks feed the same resistor & grid so it could be ANY shared connection between the jacks.

Justin

[g1]

Those are very uncommon jacks and not simple. The way they are wired up means if one is bad it can mess up the other.
Not sure where you would find them.

[pnut5150]

Yes they look different for sure. I’m not understanding how pulling the cable out a little could affect it..I mean if it were a stereo jack I could understand that

[pnut5150]

Justin I was looking at schematic it seems they definitely share the same resistors, they are jumped together also.

[Enzo]

Look at the schematic. Unless I am loopy, the extra contacts open if either jack is used. And as far as I can tell, all they do is mute the channels. Well I'd wager we can do without that feature, leaving the rest of the jacks which are plain old tip shunt jacks like a zillion Fender amps. Stick a couple Switchcraft 12A jacks into the amp, wire them as usual, and leave the mute circuit floating.

Did I miss something?

[Enzo]

Pulling it out a little affects it because the contact is bent or mis-aligned in some fashion.

[pnut5150]

Look at the schematic. Unless I am loopy, the extra contacts open if either jack is used. And as far as I can tell, all they do is mute the channels. Well I'd wager we can do without that feature, leaving the rest of the jacks which are plain old tip shunt jacks like a zillion Fender amps. Stick a couple Switchcraft 12A jacks into the amp, wire them as usual, and leave the mute circuit floating.

Did I miss something?

I get it now, I never dreamed they would mute the channels. How do you test the LDR pieces that are in these? Are they the same a a “bug” on a vibrato?

[Enzo]

Same basic idea, different execution.

As I understand it, the amp works, except you have to hold the cord just so. That means the LDRs involved with this jack mute are working. That is how you test them: see that they are working.