1969 Super Reverb tremolo tweets like a bird

[fkitch]

Hi there

Tried searching online but just found info on the well known ‘tremolo ticking’ issue, nothing on having a little bird in your vintage amp

I did a short video so you can listen to it

Noise was already present before I changed all electrolytics and dog house resistors

Noise starts a couple of minutes after powering up the amp from cold. After that the noise is permanent as long as you use the vibrato channel

Changes in volume control do not affect the tweeting noise volume

Changes in speed control affect the noise cadence (similar to the ticking noise behaviour)

Changes in intensity control do not affect volume of the noise

Any wire dressing attempts made no effect in the noise

V4 and V5 swap had no effect

Reflowed the roach eyelets solder with no effect either

All resistors within spec
I use the correct Fender footswitch

Other than some resistor hiss the amp works and sounds great

Please any ideas as next troubleshooting steps?

I also attach a picture
Thanks

[Rontone]

I can see a light flash on the video, can you see it on the end of the roach near the edge of the board, that isn't arcing is it?

Looks more like the light inside, is there a little hole on the side?

If you slow the video down the noise seems to happen as the light goes off

[fkitch]

I can see a light flash on the video, can you see it on the end of the roach near the edge of the board, that isn't arcing is it?

Looks more like the light inside, is there a little hole on the side?

If you slow the video down the noise seems to happen as the light goes off

Yes, the noise is in sync with the roach bulb flashing, that’s the light you see in the video and it can easily be seen because the bulb sticks out of the shrink tube a bit (not sure if this is important BTW)

[tubeswell]

Maybe time for a new roach and/or LFO cap change (bad ceramic caps maybe introducing unwanted coupling into signal path)?


Not saying it is this. But then again, if you've ruled everything else out...

[stratomaster]

You can give this a shot before switching out the roach.

[pdf64]

...
Noise starts a couple of minutes after powering up the amp from cold. After that the noise is permanent as long as you use the vibrato channel
 ...

So switching the trem off at the footswitch has no effect, it still carries on tweeting?

[fkitch]

Thanks for all the suggestions
Looks it is sorted
I realised that changing V4 with V5 was not the smartest option so I used V1 in V4
But what I also did (I broke my rule of doing one thing at a time) was to reflow solder in all the 3 trem oscillator in series caps eyelets

Test… and voilá , tweeting gone, just the good old ticking

Swapped  again V1 and V4 to get original tube back there and tweeting did not come back!

So looks a cold or broke solder joint was the cause… (one of them did look a bit bad)

So switching the trem off at the footswitch has no effect, it still carries on tweeting?

nope, trem off = no tweeting

You can give this a shot before switching out the roach.

did not know about that option!

Maybe time for a new roach and/or LFO cap change (bad ceramic caps maybe introducing unwanted coupling into signal path)?


Not saying it is this. But then again, if you've ruled everything else out...

thanks for the clue!!