Dunlop - UV-1 - Univibe - revision A 1997  [schematic]

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Dunlop - UV-1 - Univibe - revision A 1997  [schematic]

Postby lolbou » 01 Feb 2011, 12:55

Hi all!

Looks like a clean version now. Updates are still to happen, but I've re-checked.

Schematic (rev. 2.3).

Multilayer .svg file: here. You have 3 layers : Bottom side, Top side and Components.

For reference:
- Technology of Univibe on geofex.
- CMOS switching on geofex.
- Using a single pot+vactrol instead of a dual-pot on geofex.
- Univox Univibe LFO details on this board.
- Are you a mod or a rocker?
- Uh, no, I'm a mocker.

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Re: Dunlop - Univibe - UV-1

Postby DrNomis » 01 Feb 2011, 13:30

Just downloaded the schematic,it looks like all the CMOS circuitry is Dunlop's implementation of a pretty convoluted footswitching system,I'm surprised by the complexity of it.... :)
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Re: Dunlop - Univibe - UV-1 - schematic

Postby culturejam » 01 Feb 2011, 21:58

Would it be crazy to just drop all the footswitching stuff and focus on the actual effect circuit? :hmmm:
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Re: Dunlop - Univibe - UV-1 - schematic

Postby lolbou » 01 Feb 2011, 22:04

culturejam wrote:Would it be crazy to just drop all the footswitching stuff and focus on the actual effect circuit?
Not debugging wise I think :wink: . Because this is quite an unreliable unit, you know...

The "vintage" switch that uses a photocoupler to bypass the input buffer is cool to see.

But from a "vibe" point of view, as told in the manual, this is almost the same circuit as the original. Though the mixer differs. And since some logic is involved with it as well, it's better to see it, isn't it?

ps: oh, you mean from a circuit analysis point of view?? There's not much input about the CMOS circuitry anyway (though more than anything else! :lol: )
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Re: Dunlop - Univibe - UV-1 - schematic

Postby Tonetweaker » 02 Feb 2011, 03:07

Great stuff, loubou... I bought this bad boy with the expression pedal a couple of months back and haven't really unplugged it since.

I loved it so much in fact that I also bought the UV1SC too.

I confess... I'm a junkie. :lol:


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Re: Dunlop - Univibe - UV-1 - schematic

Postby lolbou » 02 Feb 2011, 07:01

Tonetweaker wrote:I loved it so much in fact that I also bought the UV1SC too.
Time to open it and take pictures! :wink:
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Re: Dunlop - Univibe - UV-1 - schematic

Postby Dirk_Hendrik » 02 Feb 2011, 08:15

Great work!.
The CMOS stuff is a typical case of overengineering. No clue why. It's not a piece of circuitry that one looks at and immediately detects errors. At least, I don't and especially with sequential state logic is a half analog/half digital application like this one.

First remarks for understandability/readability:

- Get that speed control away from that location. Right now it suggests having to do with the 4-stage phase circuit while all it has in common at that spot is the ground connection.
- Use a "half VCC" or Vbias or whatever label for your virtual ground connection (output of U2-2).

But;
Great work!!!. This pedal is a bitch to reverse. When I had one on the bench and measuered logic 1 on an XOR output with both inputs at logic 1 too I didn't even bother tracing and replaced all IC's straight away (which was a far cheaper jobv than hours of faultfinding)
Sorry. Plain out of planes.

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Re: Dunlop - Univibe - UV-1 - schematic

Postby lolbou » 02 Feb 2011, 09:20

Dirk_Hendrik wrote:It's not a piece of circuitry that one looks at and immediately detects errors.
I was quite confident with the tracing since all logic gates seemed to be place in the good direction, except for the U7-U9 network ("vintage" optocoupler)...


Dirk_Hendrik wrote:hours of faultfinding
Hopefully it will turn to hour_ of faultfinding with that schem! :lol: Thanks for your words and advices! :hug:
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Re: Dunlop - Univibe - UV-1 - schematic

Postby blackbunny » 02 Feb 2011, 16:19

lolbou wrote:Thanks to Dirk_Hendrik for spotting this mistake. That's what makes the difference between a hobbyist and an actual EE I guess!


Big thanks to you both!
This is a valuable resource for UV-1 owners, especially since schematics & service info for Dunlop / MXR products are nearly impossible to get.

I started checking your schematics against my UV-1, which I think must be an earlier version.

It's the same basic circuit, but less CMOS switches, and a different layout .
Most transistors are MPSA18's, IC's are TL071, TL072 & TL074's plus a couple of CMOS switching IC's.

I have never had a problem with it yet, so I never had to fix it or figure out how it works.

The pcb looks like this.
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Re: Dunlop - Univibe - UV-1 - schematic

Postby Dirk_Hendrik » 02 Feb 2011, 18:29

Lolbou,
can you post this schem (or mail it) in a .gif format so I can make some suggestions to be checken in it?
Sorry. Plain out of planes.

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Re: Dunlop - Univibe - UV-1 (Rev.A 1997) - schematic

Postby lolbou » 02 Feb 2011, 19:42

blackbunny wrote:I started checking your schematics against my UV-1, which I think must be an earlier version.

It's the same basic circuit, but less CMOS switches, and a different layout .
Most transistors are MPSA18's, IC's are TL071, TL072 & TL074's plus a couple of CMOS switching IC's.

The same evolution happened to the Rotovibe I think. The early version of the Rotovibe can maybe somehow close to your Univibe version (and the schem for the early Rotovibe is available through google).

I renamed the thread to indicate the PCB rev. number and date. If you do have more pics and some other PCB details, maybe some other thread can be started to make it clear for members looking after a specific unit?
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Re: Dunlop - Univibe - UV-1 (Rev.A 1997) - schematic

Postby lolbou » 03 Feb 2011, 22:45

Update to Rev 2.0 is here!!

HUGE THANKS to Dirk_Hendrik for the help and drawing solutions he provided. :applause: :applause:

Mixer appears more clearly now, so does the switching and speed control.

Some more double checking to come, but this is being quite close now I guess...
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Re: Dunlop - Univibe - UV-1 - schematic

Postby Tonetweaker » 04 Feb 2011, 05:34

lolbou wrote:
Tonetweaker wrote:I loved it so much in fact that I also bought the UV1SC too.
Time to open it and take pictures! :wink:


I'd be happy to. I have a lot of pedals, but I never know which ones are worth the time to pull apart and take gutshots. A lot of the ones I have aren't vintage, and quite a few of them have already been dissected, so unless I get something out of the ordinary, I usually assume it's already been done. I'm also on an exceptionally slow dial-up connection, so it takes quite a while to upload pics (thank God I don't have to use PhotoBucket to host them though!)...

I have another pedal to post some gutshots of tonight, but I'll definitely do that one for you over the weekend. :thumbsup


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Re: Dunlop - Univibe - UV-1 (Rev.A 1997) - schematic

Postby lolbou » 05 Feb 2011, 00:59

Now, in my unit, The two expression pedal jack tip connectors are jumpered with a wire added over the solder side of the PCB. Is it factory done in your opinion? Or is it some kinda mod the previous owner did try on the unit?
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Re: Dunlop - Univibe - UV-1 (Rev.A 1997) - schematic

Postby blackbunny » 05 Feb 2011, 01:37

There's no jumper on my (older) version. You mean the middle jack on the main pcb, where you plug the pedal in?

Maybe your UV-1's previous owner had some trouble with the rate control, caused by dirty or bent contacts in the jack socket.
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Re: Dunlop - Univibe - UV-1 (Rev.A 1997) - schematic

Postby lolbou » 05 Feb 2011, 12:49

blackbunny wrote:You mean the middle jack on the main pcb, where you plug the pedal in?

Maybe your UV-1's previous owner had some trouble with the rate control, caused by dirty or bent contacts in the jack socket.
Yeah, that's the one... I thought about a kinda repair, but the jack contacts seem in very good condition...

Luckily enough, I've repaired one of these Uni-Vibe some years ago (same PCB), and just found the pics no extra jumper, and as far as I know it's working ok with the foot controller: I'll remove it and see.

The missing Q19 is 2N3904 and missing R98 is 10k in Dirk_Hendrik's unit as he stated in the old thread I mentionned. I think these are in place in my friends unit with no noticeable changes...

BTW, comparing the two units, it seems that TP1 is roughly set in the same position (9 o'clock) whereas TP2 is a bit more different (more like 3-4 o'clock for mine, and 1 o'clock for the other one), with 12 o'clock being with wiper in middle position.

I believe these trimpots are for adjusting the optocoupler LED's bias and get a correct speed range?
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Re: Dunlop - Univibe - UV-1 (Rev.A 1997) - schematic

Postby lolbou » 05 Feb 2011, 13:33

Update to rev. 2.2. Bias network arranged at U8-2 inputs.
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Re: Dunlop - Univibe - UV-1 (Rev.A 1997) - schematic

Postby lolbou » 05 Feb 2011, 21:39

blackbunny wrote:Maybe your UV-1's previous owner had some trouble with the rate control, caused by dirty or bent contacts in the jack socket.


Wire desoldered: no contact, as well as for ring contact. This might explain also why I bought this one used for 50 euros with the effect/bypass switch being disabled...

Edit: it vibes again perfectly... 8)
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Re: Dunlop - Univibe - UV-1 - schematic

Postby Tonetweaker » 06 Feb 2011, 04:30

lolbou wrote:
Tonetweaker wrote:I loved it so much in fact that I also bought the UV1SC too.
Time to open it and take pictures! :wink:


lolbou ~ No hijack intended... but I wanted to let you know that I took the UV1SC apart tonight and created a thread for the gutshots. Enjoy! :)

I haven't actually taken my UV1 apart, but I'd suspect the two units share a bit of common circuitry.


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Re: Dunlop - Univibe - UV-1 (Rev.A 1997) - schematic

Postby blackbunny » 06 Feb 2011, 05:27

lolbou wrote:Wire desoldered: no contact, as well as for ring contact. This might explain also why I bought this one used for 50 euros with the effect/bypass switch being disabled...

Edit: it vibes again perfectly...


Great news.

I'm sure you will enjoy playing through it and you can now reap bountiful rewards from your efforts.

Tonetweaker wrote:lolbou ~ No hijack intended... but I wanted to let you know that I took the UV1SC apart tonight and created a thread for the gutshots. Enjoy!

I haven't actually taken my UV1 apart, but I'd suspect the two units share a bit of common circuitry.


Nice shots. It looks like there may be a little less circuitry than the UV-1....have Dunlop changed their approach and re-designed the UV-1 as a less complicated circuit?
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