Dunlop Univibe not fast enough!

[harpplayer]

Hi there! Quick question. I have a Dunlop Uni-vibe UV1 that the fastest setting is just not fast enough. Actually, it is not really fast at all, and I´d like more helicopter like settings.

Is there a way to mod it? I thought it would be something as simple as with the CE-2, but clearly it is different. Here is the schematic portion I found. Changing the 92k resistor would only limit the pot action, whereas changing the pot to something like 100k would change the resulting value, but I don´t think this would make it any faster, only more control over the slow settings.

Anyways, any ideas are really appreciated!

Tks!
André

[harpplayer]

Oh, the 22 meg bias resistor is actually 72k, that was a mistake on the schematic, but I don´t think it is related to the speed anyway.

[harpplayer]

Anyone?

[harpplayer]

Well, after reading RG Keen´s technology of the univibe, I understood that the speed doesn´t have to do with this control directly. The LFO portion of the circuit determines the slowest and fastest speed availabe.

Dunlop´s univibe is different from the original univibe and many aspects, but the LFO part seems close in design with only different values.

So, from the image below, if I reduce the 220ohm resistors close to the diodes, I should get faster speeds, right? Would this cause damage to the lamp because it will blink faster?

I realize I am only talking to myself now after all these posts, but please, any knowledge is very well welcomed!

Tks,
André

[harpplayer]

Image 

[harpplayer]

Just in case anyone wants to know, I tried 1 ohm instead of 220 ohms for the two resistors on the lfo and the speed is much faster now. It sounds a bit odd on maximum speed because the modulation is not so swirly, but it is cool.

With the expression pedal it hasn´t changed, and I think it would take a lot of modifications to make it behave like the speed potentiomer, so I am going to leave this for now.

[Boba7]

Glad you got it working!!

[maggit13]

i just fixed my univibe after it got damaged in a flood 10 years ago and only would run at half speed. I replaced every capacitor, several resistors, transistors, chips, etc., nothing worked. Finally, the last thing i decided to check was the optocoupler, and guess what... That was the problem, sheesh.

Anyway, now it's running great again but the max speed is cut in half when the expression pedal is plugged in. Everything works fine and it changes the speed, but it's not nearly as fast as it is without the pedal plugged in. I see you mentioned above about modding the pedal, is this a known thing where the speed is slower when it's plugged in?