danelectro explorer, tremelo problem

[carter]

the tremelo on my vintage danelectro explorer amp does not work. The rest of the amp sounds gorgeous and I'm sure the trem will too but I have no clue where to start with fixing the tremelo.
Are there typical problems with most amps that cause for the dissappearance of tremelo? Is it a bad tube? thanks

[ckeene]

if it's like a Fender, the trem circuit should have its own tube, which is a good place to start looking.

Do you have a schematic, or can you find one online to post?

-ck

[carter]

i'll check internet for schematics. thanks

[carter]

any idea what tube runs the tremelo circuit?

[TooLoFi]

Open it up and trace the cable(s) coming from the vibrato knobs on your amp panel. Trace the circuit and see what tube it's all going to. Don't touch anything inside until you drain the filter caps, or measure to see that there is no voltage. Alternatly, pull out tubes one by one. If you loss reverb, that's the reverb tube, if you loose vibrato, that's the vibrato tube. or swap your reverb (assuming you have reverb) tube with another similar tube on the amp.

[carter]

The tube that works with the tremelo circuit is a 12ax and I swapped it with one from my bassman. Still no trem... what is the next most common reason for these to stop working?

[lacquer_monkey]

The tremolo in most amps is a phase shift oscillator driving an optocoupler of some type. In the case of most Danelectros, this signal is used to basically short the first stage preamp output to ground. SO either the oscillator is not running, or the optocoupler has failed. In order to know which it is you need to look at the output of the oscillator and see if it is working. If it is working then the problem is probably the optocoupler.

[carter]

good to know