Vibrosonic Reverb Vibrato Problem

[dstiner11]

I'm new here but this is a cool site.

I have a Fender Vibrosonic Reverb which I love but when I turn the vibrato intensity up the volume goes way down. It is basically a Fender Twin Reverb chassis. Does anyone know what could cause this? Otherwise, the amp sounds great. Thanks in advance!

[mac1amps]

If you're losing volume by turning up the vibrato intensity control it usually means that the photocell (LDR) is defective.

[dstiner11]

Thanks!

I'll open her up and check it out. I'm not sure how to test it so I may just order a new one and try it.

[Amp Kat]

If you pull the chassis and turn it up where your looking at the main board. Fire it up and make sure you have a load on it or the volume turned all the way off. You'll see a black thing about 3/4 the way on the board that looks kinda like a roack and is wrapped in black heat shrink. If you dim the lights and turn the intensity and speed up it will be blinking on and off. The faster the speed the faster it blinks. If it does this it is most likely good. You do have the rca in the back shorted or the footswitch plugged in right ?

[dstiner11]

Thanks. I had my friend's old Fender Twin on the bench today to put new caps in it and I saw the strobe with heat shrink around it and the photoresistor. It's in the same place on my Vibrosonic. I'll make sure I have my guitar plugged in and the speaker connected. I'll also make sure the footswitch is plugged in. I guess if it's good, then it must be a bad component somewhere close. I haven't worked on amps enough to have a good clue but it's sure fun as long as I can keep my bare fingers from touching anything. I'll let you know what the results are. Thanks again.

[Bruce / Mission Amps]

Also, even if the neon light is blinking, it is the cell inside the roach that is effected by the neon bulb... if the cell has gone bad the vibrato won't work right.

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