A buddy of mine brought me a vintage phase 90 (6 single opamp version). I passes signal just fine but the phase signal gives me nothing. I've checked all of the ICs and they each are getting powered properly (9V on pin 7 and 0V on pin 4). I pulled out the audio probe and I noticed that the signal gets attenuated after the first capacitor and then comes out of the input buffer incredibly weak. From their I think the simple filtering in the rest of the audio path kills the signal off. Any phaser folks had experience with this?
I'm getting the appropriate 5.1V off of the Vref so I don't think that's an issue. I've been using the Electrosmash phase 90 analysis page to help me sort through the signal path.
Personal Update: Looks like the caps in the signal path may have drifted so far out of spec that they're filtering out the signal entirely.
I have a diy phaser 90 build that only sounds in the off position?
I used the Audio probe & I get a phased signal from the left side of the board, nothing passes by the green line.. R3, 4, 5, 6, & Q1, 2, 3, &4.
See the pic attached.
Any ideas?
Got pics of your build (both sides) along with voltages?
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As far as voltages, I am new to DIY builds so I need a description of how to do voltages. EX: Do I ground to box & with unit in the on position, touch each component on the board to get the DC voltage reading? Thank you for your assistance.
Did it work before and then not work? Did you try turning the trimmer in mm increments? Did you check to make sure all of the parts are correct and have you reflowed all of the solder joints? Sorry for all of the questions, it's a process starting with the above.
Ground the DMM probe to the main ground, the red probe will check each leg of the ICs and transistors.
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Some of those solder points look highly suspect. You may want to clean that off with some alcohol and a brush and re-flow. In your pic, the lower right corner.... Pin 6 of that Op Amp looks bad :-\
Thanks, Jimilee & Govmnt_Lacky.
I will clean the rear of the board, re-tin the joints & then do the readings, Greatly appreciated! I'll get back to you later.
An update, Jimilee, after I first finished the build it did work, but only in the on position, I got a new push-button from the supplier of the kit for free because he said I was probably too heavy with the heat & melted it. After installing the new switch was when I got the results I originally posted above. I have cleaned & resoldered all the joints, but still have the same results as above. I am now doing the voltage readings & will post them soon.
Looks like there a missed solder joint on the bottom right.
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The open solder joint is for the jumper to use as a script model. Attached are the voltage readings and a copy of the board labels.
(https://uploads.tapatalk-cdn.com/20210210/3157cd34667e45ec8fca2bd9311d6f53.jpg)
Are both of these spots not supposed to be soldered?
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I see these 2 spots not soldered, I will ask the site I bought it from & get back to you.
(It's actually these 2 spots, the lower left one in your pic is soldered.)
Thanks.
Quote from: mgalicki on February 10, 2021, 04:00:57 PM
I see these 2 spots not soldered, I will ask the site I bought it from & get back to you.
Thanks.
Both of those solder points are legs from IC chips. They need to be soldered properly. Those were the points I mentioned in my previous post.
All IC chip solder joints have been soldered. There are 2 large unsoldered holes in the board I am asking the seller about.
Quote from: mgalicki on February 10, 2021, 04:45:20 PM
All IC chip solder joints have been soldered. There are 2 large unsoldered holes in the board I am asking the seller about.
Those 2 large holes are for mounting the PCB in the enclosure by plastic standoffs.
I am guessing that you went through and re-flowed all solder points again since taking the above pictures. If not... you really need to.
In the meantime...cool to have an original board or a copy of it.
So the seller said the 2 holes in the board are to be left open. Nothing gets soldered to them.
From the Seller:
You do have the ICs oriented correctly? ICs 2 3 4 and 5 are facing opposite direction from IC 1 and 6. Let me know.
I think you may be off in following the audio path. The audio splits after IC1 and goes with a clean sound to R27 and the other split goes to C2 and R7 to go thru the 4 stage phasing process.( thru ICs 2, 3 4 and 5), you should hear the phasing warble getting more intense on Pins 2 and output pin 6 of those ICs. Then the clean and warbled sounds are mixed in the pnp transistor stage just before output.
You won't hear any sound anywhere on the FET Pins as they are there for the sole purpose to fluctuate the current going into the phasing ICs at whatever rate the LFO is set to be (LFO being the circuitry around IC6 and controlled by pot R21). SO...if you are not getting any sound on the left side, not even to pin 2 of IC2, you would need to find out what's happening to the sound between pin 6 of IC 1 and pin 2 of IC2
So, great news! I guess resoldering all the joints fixed it! Praise to you all for your comments. My first DIY has become a success thanks to madebeenpedals Guru's.
Woohoo!! Congratulations. That fixes about 98% of your issues.
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So what's the other 2% of my issues??
Quote from: mgalicki on February 11, 2021, 04:44:28 PM
So what's the other 2% of my issues??
He meant to say "Re-soldering your joints will fix your issue 98% of the time."
But... it's more like 50% ;)
Gotcha, so now that it's workin I'm thinkin about adding the script mod with a mini push button. Where would I get that?
Thanks
Quote from: Govmnt_Lacky on February 11, 2021, 05:20:38 PM
Quote from: mgalicki on February 11, 2021, 04:44:28 PM
So what's the other 2% of my issues??
He meant to say "Re-soldering your joints will fix your issue 98% of the time."
But... it's more like 50% ;)
I guess it's subjective. Either way, it's a good starting point for troubleshooting.
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Quote from: jimilee on February 11, 2021, 10:10:30 PM
I guess it's subjective. Either way, it's a good starting point for troubleshooting.
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Agreed! As your skills with the iron progress from Padawan to Jedi, your chances of solder joints being the issue greatly decrease. Then, it becomes dumb mistakes like connecting Input and Output wires to the wrong sides of jacks.... take it from me ;D
So could I put a potentiometer instead of an on/off switch on R28?
Well I did it, the effect does soften when dialed down about 25%. But I can only dial it back about 25% before the volume starts to drop along with the effect. cool stuff.
Welcome to diy man. I love me some phasery goodness.
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