Dunlop Univibe info?

[drewl]

Anyone have a schem or info on the Dunlop Univibe?
I was able to ressurect one, however the LED is supposed to change from the red one the the green when when changing function.
It seems like they are tied in parallel (pc board damaged) so I was thinking maybe the voltage level changes to fire the different LED.
any ideas?

[Regis]

R.G. Keen has a whole white paper on the univibe at his site:

http://www.geofex.com/Article_Folder...e/uvfrindx.htm

harpamps has full schematics:

http://www.harpamps.com/schematics/

[drewl]

Totally different animal from the newer Dunlop version...but thanks for the interesting links!

[pianoman]

Solution to Uni-vibe repair

This may be way too late, but I just stumbled across this forum. I, too, was in search of a schematic for a Dunlop Uni-vibe as the one I have had exactly the same problem as you are describing. This one would not change functions from vibrato to chorus and the bi-color LED also would not change. After replacing several of the CMOS ICs, I discovered that a defective 4070 was causing this problem. There is only one on the PC board. Changing that chip fixed this pedal. It might also be a good idea to socket the board when you change this/these ICs as this is a very high quality board (near mil spec) and is difficult to repair without damage unless using a professional desoldering station with vacuum.

Hope this helps. Cheers.

Pianoman
Nashville

[qwixzh]

I too have a problematic Dunlop univibe.

Got it used, first the issue was the the speed knob is not functional. Then after opening the pedal several times, the pedal wont function anymore, its always in a bypassed mode.

hope somebody can fill-in.

thanks in advance!

qwixzh

[pianoman]

Possible fix - Dunlop Univibe

They used rather brittle ribbon cabling between the footswitch board and the main PC board in this model. In the course of repairing this one I had, it was necessary to redress the entire end of the cable where it connects to the Main board and is flexed the most. I think 5 out of the 10 wires had broken at the vias on the board. This will certainly cause what you are describing and may also be the original cause of the first failure.

It's best to remove the entire cable (from the Main PC board), strip, tin and reconnect all 10 wires. Doing one at a time will invite more problems.

Hope this helps.

Cheers,

Pianoman
Nashville

[qwixzh]

thanks Pianoman! I'll give it a shot today.

I just emailed Dunlop and they said that my univibe was the first version (PCBs are rev. F) The tech support guy said that they dont repair it anymore but will gladly replace the unit with the latest version if I ship mine to them. They will only charge me a total of $50 for the new unit, shipping cost included (i'm from the Philippines).

Anybody think it's a good deal? Any difference, tone-wise? Is it better for me to just repair my unit? Or nothing has changed from that first version to the latest.

thanks!

[pianoman]

Univibe repair

Actually, since yours is an earlier version (I didn't know that when I replied the first time), you'll probably end up with the 'digital' version in the deal. Probably not a lot of difference in sound as they both use the same quad LDR photocell system. I don't know if the original had a 'Vibrato' feature or not, but the later ones do - effect on/off and Chorus or Vibrato and a provision for plugging in a variable sweep 'volume' type pedal. I'd still check that cabling first. You might save yourself 50 bucks.

pianoman
Nashvegas

[qwixzh]

yup, mine has a vibrato/chorus switch.

although mine doesn't have this additional switch (vintage) on the jack side.



I havent touched the pedal yet, probably later.

thanks again!

[cjlectronics]

I've repaired a few of the older Dunlop Univibes. Its a Pain the butt to get the board out. So far, every unit I had required re-soldering parts on the pc board... even though its a double sided pcb? The jacks are cheap and one had a broken jack. Replaced it and the unit worked fine after that.

[lolbou]

I too have a problematic Dunlop univibe.

Got it used, first the issue was the the speed knob is not functional. Then after opening the pedal several times, the pedal wont function anymore, its always in a bypassed mode.

hope somebody can fill-in.

thanks in advance!

qwixzh

Sorry for the late replying (bump!) but I just repaired one with the same problem. The LED part of the optocoupler was weird, I desoldered it, checked it, and since it was good, I resoldered it properly. It works now!

As for the bypassing, check for broken wires (or better all of them) for the pots and switches boards... Best is to replace them all, it'll work again...

Hope that helps, to bad there ain't any schemo on the internet...

[lolbou]

Bump!

Rev. A schematic is available here...

Hope that can help in the future...

[falcopryor]

Hope someone will still read this.. Dunlop switch issue but different

My pedal works fine until you bypass it at the pedal or footcontroller... then it won't switch back 'on' again unless you unplug it and replug it. Everything else works as it's supposed to... help?

thanks in advance..

Bump!

Rev. A schematic is available here...

Hope that can help in the future...