Build Your Own Clone Message Board

I have a problem with a phaser similar to what Mantas had described a while back. I'm not getting any auto-sweep but do get a sweep when I turn the trimpot. It sounds to me like the LFO is not quite working.

This is my 4th phaser but the first with any issues. It's a 2006 board, I sourced the board and JFETs from BYOC (matched set), and added a depth and feedback control. The feedback is working fine. I have a 16uF tantalum cap in the 15 uF position, polarity is correct.

I know the drill but haven't ripped it apart to freshen up the solder connections yet.

My question is: what are the components of the LFO - other than the 15uF capacitor? I think that is where my problem is and I'd like to concentrate there first.



Thanks,
Morgan

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

bump

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

Morgan,

Double check the orientation of your tantalum caps. I put mine in backwards and had the exact same problem. If you put them in backwards, there may be a good chance that you also fried them

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Keep 'yer tips tinned, 'yer sponges wet, and TELL THEM KIDS TO SHUT THE HELL UP!!!

Thanks Mantas. That was the first thing I checked after reading your post. They're in the right way.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

Bump.

Can anyone point out the components of the LFO in the phaser?

Thanks.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

I know after experimenting with my phaser I found a few resistors that when cut off killed the lfo. Unfortunately this wasn't what I was looking for, so I didn't mark them. But there's a good chance your problem lies within a few resistors.

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Pfft, what kind of loser takes the time to make a signature?

So you don't have an idea of which few resistors those were?

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

So I went in and re-flowed solder, doubled checked component layout and checked continuity for as many connections as I could with no change.

When the pedal is engaged, I get the phaser tone without oscillation. If I manually sweep the trimpot, I get phaser oscillation through about 30% of the pot rotation. You might notice that I did the vibe mod with a 4PDT. That seems to be working fine - when I flip the switch, the tone changes noticably. The feedback pot works fine. Neither the depth nor speed controls affect anything.

Any ideas?

Thanks,
Morgan

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

Oops - double post...

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

Morgy,
If I am correct, R11 should be 3.9m ......is it?

Geek

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Everyone likes sausage. Nobody wants to see how it's made.

Yeah it is. Those 3.9 meg resistors are the only carbon film resistors I have, so they stand out to me.

I appreciate you taking a look though. Any idea what makes the thing oscillate?

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

10% carbon film resistors? I didn't know they still made those.

There's a scheme for the phaser stickied at the top of this lounge. Even if you don't know how to to read a scheme, I think ifyou look at it for a few minutes it will start to make sense. The LFO consists of the op amp (triangle shaped thing) in the lower right hand corner and all the componens that are directly connected to it, including the rate pot.

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*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Right on - thanks Keith, I'll have a look. LFO's don't make sense to me. I just can't wrap my mind around why those few components would make the signal sweep like that.

Gold stripe at the end means 5%, don't it?

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

Yes. Brown = 1%, Gold = 5% and Silver = 10%

I meant to say "20%"! red stripe means 20% right. the colors look really weird, but the 10k resistors look like they are 20%

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*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Damn! I thought you were onto something there - hoping I misread the code and put in the wrong values. Red Stripe = good Jamaican beer and 2% tolerance (I'm a sucker for those brown resistors). The brown resistors are metal film by Vishay, I was talking about the loner carbon film 3.9 meg before.

Still no disco. But I haven't started replacing components yet.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker