Dunlop UV-1 Uni-vibe: Common Problems & Fixes

[Dingus]

Hi guys,

         I recently purchased a broken UV-1 with the intention of just sending it to Dunlop for their flat-rate non warranty repair service which is like $50 or $60, since I got the UV-1 for only $15 + shipping it was a deal. So I called Dunlop and they said that they no longer fix those if they are not under warranty. Apparently they came out with the newer model (which has the Vintage switch in the back) and that is the only one that they repair. They must have had some crucial design changes to make such a decision.

Anyway I search around the forums here and saw a couple of responses that people with broken ones had, but I just wanted to put these all in one place, and hopefully be able to fix my broken UV-1 with the knowledge and information all of you wonderful people provide. I'll start mentioning mine and whats wrong with it and I'll reference the other posts I found on here about it, so they can all be in one place.

Symptoms: Unit lights up when powered by correct adapter, and switches work and LED's change color, but no signal passes through the unit what-so-ever. I opened the box up and the first thing I noticed was burned caramel looking marks around this little silver box, which I had not seen in a circuit before, but assumed it was the lamp housing, especially since I couldn't find a lamp anywhere else. Then I read up on the UV-1 some more and the technology behind it, there are some great articles out there on the old one, and we truly are living in the golden age of effects to have this information so readily available. ANYWAY... I also noticed that it appeared that C1 is absent. It doesn't look like there was ever a capacitor soldered into C1, so maybe that was a later decision to leave it out before production began.

So I'm not sure what to do, but here are links to what others have said about the Dunlop UV-1 on this forum. I have checked the Ribbon cables and they are connected fine. I have also tried cleaning the contacts and still no luck.

http://www.diystompboxes.com/smfforum/index.php?topic=44788.0

http://www.diystompboxes.com/smfforum/index.php?topic=42354.0

So I can try: Replacing Footswitches, Replacing Voltage Regulator, Replacing Lamp Drive Tranny, Replace Control Input Jack

I think that's it. Do the burn marks around the lamp housing suggest that I might have to replace some photo resistors or the lamp?

Thanks for any help you guys can provide.

[alderbody]

You could start by carefully removing the light shield, to see if the bulb is flashing.

But in order to do a correct debugging, read the relative sticky for info on what to do when something doesn't work.

btw, if you are not experienced in electronics, i think that the uni-vibe is not the best circuit for you to start...

not exactly for it's complexity, but for the difficulty to fine-tune it in order to sound right.


good luck!

[RedHouse]

Symptoms: Unit lights up when powered by correct adapter, and switches work and LED's change color, but no signal passes through the unit what-so-ever.

The Dunlop "Uni-Vibe" isn't just like the Univibe circuit we see around here, the Dunlopp one uses a bunch of CMOS switching for the signal path that is not present in the normal/standard Univibe.

You could start by carefully removing the light shield, to see if the bulb is flashing.

Since the description of the problem was "no signal passes through" I wouldn't spend too much time looking at the lamp or LFO. When the lamp (or LFO ) is out in a Univibe the signal still passes through, just doesn't phase.

[dosmun]

1st thing I would check is all of the ribbon cable connections.  Then after that check them again.  They break very easy. I repaired one and I had checked them all out and had a few break after I checked them just trying to get it back in the enclosure.

[BDuguay]

Another common problem with these pedals is the pedal input jack. Give the contacts on that jack a good cleaning and that might solve your problem.
B.

[Dingus]

Thanks for the suggestions guys, yes I noted the Ribbon Cables, and they seem fine. I'll have to try cleaning the input jack.

Out of curiosity do you guys know what board revision of the Dunlop Uni-Vibe you worked on?

On my Uni-Vibe's board it says Rev F

I was just wondering if that's the reason its not so easy to get a schematic, because they put out so many revisions of it.

I also just purchased (a working) one of the newer Uni-Vibe's with the Vintage Switch that was manufactured in March '06, I'm gonna open that one up when I get home and see what board Revision that is.

But yes thanks again, and keep the suggestions coming, I havent gotten a chance to try replacing the footswitches, Replacing the Voltage Regulator, Replacing the Lamp Drive Tranny yet.

Do those burn marks mean anything though? I heard that when Electrolytic Capacitors die they sometimes leave a burn mark looking residue.

[dosmun]

I havent gotten a chance to try replacing the footswitches, Replacing the Voltage Regulator, Replacing the Lamp Drive Tranny yet.

For the Voltage regulator just check to see if it is putting out 15v
Most of the stuff you mentioned you should be able to check before replacing.

[Duskb]

Sorry for necroposting here but this thread seemed to be the most appropriate place to post this. I have a univibe that recently stopped working correctly.

Symptoms: no vibrato effect.

Unit power ok. Leds function properly. When I bypass and engage the circuit I hear the tone change also when I switch modes the tone changes as well, this leads me to believe the circuit is fine but whatever drives the vibrato effect is out to lunch. I resoldered/heated all the obvious connections to no avail. I did pull off the silver lamp cover and when the unit is on the lamp is dead (or not doing anything).

Anyone have any suggestions on where to start? I think this one might be salvageable.

(BTW when I got this unit it did the same thing but after reseating some cards and thwacking it a few times it came back to life for many years. That didn't work this time.)

Update: poking around inside I noticed moving my fingers close to the optos caused the tone to change. Of course doing it rapidly made the vibrato com to life. My guess either some of the panels are dead and/or the bulb is dead. How do I source this?

[pinkjimiphoton]

the bulb is dead. or whatever drives it is. the phaser part is working, if it changes, and passes signal as you move your hand over it.
google up a schematic for it, its in the drive part for the lamp i think you have the problem.

lamp is 12v, 40-80ma

check the bd681 transistor, its the biggest one on the board i think

[R.G.]

The univibe is one of the most thoroughly known pedal circuits on the planet. I posted my first layout for reproducing it back in the late 1990s, and it's been hacked on ever since by the community at large.

What you need to do is read "Debugging: what to do when it doesn't work" and follow the instructions there. If you can do that, it is very likely that I or one of the others here can tell you what is wrong, and likely what parts to replace.

[Duskb]

Sorry to continue to be a pain on this but I have had zero luck sourcing a bulb for this device. A Google search for 12v 80ma lamp came up with two possible bulbs in the UK, I ordered one off of Amazon and it was too tiny and small to use, digikey claims to be out of stock. Does anyone have an actual part number or source for a bulb that would work?

[pinkjimiphoton]

https://www.mouser.com/ProductDetail/JKL-Components/7219?qs=Xy34DXS8EhasFVwWUc6rig%3D%3D

60ma, 12v, leaded t-1 34 size

.71$ american a piece. should be fine, i'd think. right in between 40 and 80 ma.

check here too, 14v is likely close enough for rocknroll

https://www.mouser.com/Optoelectronics/Lamps-Holders/Lamps/_/N-5g6r?P=1z0yt47Z1z0ys5r