Hi
I have a Rotovibe JD-4S since the 90's and never encountered any issues with it until yesterday.
The pedal was unused for like 6 months and shelved. When I plugged it yesterday I was stunned to hear the signal passing through but... no effect, no modulation or anything but the dry signal. Either in vibrato or chorus mode.
When I change the mode I can hear a difference in the sound but the signal remains dry.
The pedal is powered by a Dunlop DC brick in 9V, it lits up but the signal is dry.
I'm not digging electronics at all...
Anyone has experienced such an issue with a Rotovibe? By any chance...
Any kind of help will be appreciated. Thanks in advance.
Dunlop Rotovibe JD-4S 90's - FX is not working anymore
-
stolen
- Breadboard Brother
Hi!
There's a chance that this actually is a mechanical issue, assuming that it's the same model as gutted here:
viewtopic.php?f=1&t=2335&p=49960#p49960
From your description the most likely cause is that the oscillator has stopped working. The 4 black tubes at the heel end of the pcb are "homebrew" optocouplers; with a little luck (and the room lights dimmed) you might be able to see the LEDs glow a little through one of the ends if they are not completely sealed. If that glow is constant, then it's definitely the oscillator; crank the intensity pot for this test (or use the middle position if you're not sure which position is cranked).
This fault could be caused by many things, but since you said it occured while shelved a likely cause could be mechanical contact problems with the speed pot; this would cause this (very weirdly implemented) relaxation oscillator to stop and explain the behavior. Maybe unplugging, cleaning and re-plugging the connector could solve this problem! If not, you could try shorting the outer pins of the speed pot to see if the potentiometer itself has suffered mechanical damage. If shorting brings back the effect at a very fast rate, chances are you'll need a new pot.
One of the trimmers on the board (we can't tell which is which) labelled RP3 on the schematic sets the modulation bias and can be used for "manual" vibing; if you mark their original positions with a sharpie and are willing to play around with them a little, you should be able to hear a change in sound in the chorus mode when turning the right trimmer. This should be also visible as a change in brightness at the optocouplers. If that doesn't work, the LED driver is likely to be done for, but we consider that very unlikely if no wrong power supply was used since the last time it worked. The other trimmer sets the maximum speed by the way, so you're not sacrificing a magical calibration when you don't get them back into the original position to a hair
.
Maybe this helps a little!
There's a chance that this actually is a mechanical issue, assuming that it's the same model as gutted here:
viewtopic.php?f=1&t=2335&p=49960#p49960
From your description the most likely cause is that the oscillator has stopped working. The 4 black tubes at the heel end of the pcb are "homebrew" optocouplers; with a little luck (and the room lights dimmed) you might be able to see the LEDs glow a little through one of the ends if they are not completely sealed. If that glow is constant, then it's definitely the oscillator; crank the intensity pot for this test (or use the middle position if you're not sure which position is cranked).
This fault could be caused by many things, but since you said it occured while shelved a likely cause could be mechanical contact problems with the speed pot; this would cause this (very weirdly implemented) relaxation oscillator to stop and explain the behavior. Maybe unplugging, cleaning and re-plugging the connector could solve this problem! If not, you could try shorting the outer pins of the speed pot to see if the potentiometer itself has suffered mechanical damage. If shorting brings back the effect at a very fast rate, chances are you'll need a new pot.
One of the trimmers on the board (we can't tell which is which) labelled RP3 on the schematic sets the modulation bias and can be used for "manual" vibing; if you mark their original positions with a sharpie and are willing to play around with them a little, you should be able to hear a change in sound in the chorus mode when turning the right trimmer. This should be also visible as a change in brightness at the optocouplers. If that doesn't work, the LED driver is likely to be done for, but we consider that very unlikely if no wrong power supply was used since the last time it worked. The other trimmer sets the maximum speed by the way, so you're not sacrificing a magical calibration when you don't get them back into the original position to a hair
.Maybe this helps a little!