fender tremolo question

[blanik]

i have a question, the tremolo in my Twin Reverb (silverface) was repaired some time ago (it never worked for the 15 years i owned it but i wasn't using it), it works fine now but when i press the switch on the first time no effect can be heard for several seconds, i have tu strum hard on the strigns for a while then the tremolo effect appears after that it works ok until i close the amp, then it does it again everytime i open my twin (no matter how long i let it warm-up before lifting the bypass switch)
is this normal?
(i know that only one or two caps were changed in the repair, they didn't touch the LED/LDR assembly)


R.

[R.G.]

The Fender tremolo is sensitive to the gain of the tube that makes the LFO oscillator. If it's a little low on gain, it may not start reliably. This can be from tube aging or component drift.

[John Lyons]

Also, pretty much any 12AX7 tube that works will operate the vibrato of a fender amp. The Oscillation function tube doen't require a good sounding tube. Any tube that says 12ax7 should work. If you have a spare one or can get a cheap one somewhere, most likely it will fix your problem. Sometimes the layout of wires will make the Vibrato oscillator stop but It seems that it does work after you play a bit, in your amp.

Pull out the first tube in the Normal channel (on the far left as you face the back of your amp) and plug it into the 5th tube socket from the left (which is the vibrato tube) See if the vibrato works that way. If it does then you just need another 12aX7 to replace the bad vibrato tube.
There is a tube chart in there on the side panel if you get lost.

john

[blanik]

thanks guys, i didn't thought about changing the tube, i thought it had more to do with the new caps... i have a ton of old tubes lying around so i'll try some of them to see...
yes this "problem" is only when i initially start the amp, once the tremolo starts working it's OK for the rest of the show/rearshal

i was just wondering if it was a bug or the usual way of old fender trems...

R.

[John Lyons]

I re read the first post. If you have to hit ther strings hard and then after that it's fine until you turn the amp off... It may not be the tube. Seems like something is needing to be pushed open and then it satys working... CAP???
Let us know...

John

[blanik]

yeah, a cap was my first impression... i just wanted to make shure it was not a normal behaviour for a fender tremolo... it would have bugged me to bring the amp back at my dad's place, re-open it, search for a problem we can't find to finally learn a week later that it's normal for fender trems to do this on startup... 

but it seems it's not usual so i'll feel more confident to re-open it... i'll start with the caps that we changed first (2 i think) maybe we need to change a third or we put the wrong value for the repl. ones...

i'll keep you posted

R.