Author Topic: MXR Flanger redone (Read 52328 times)

aeroguitar · « **Reply #20 on:** August 10, 2011, 06:49:47 PM »

Hello guys, thanks for the help of all, I'll see if I can copy the daughterboard using a program like Corel Draw, or any other, but I think it will be very difficult, if not I'll try to get pass the Eagle schematic and try to to build a new layout for this purpose!
Thanks for now!

omnitek · « **Reply #21 on:** August 29, 2011, 11:52:05 AM »

Hi everybody,

I'm trying to repair a vintage MXR Flanger with a MN3007 instead of a SAD1024.

I installed the MN3007 on a daughter board and the pedal worked fine but it stopped working when I installed the chip directly on the main board.
Now, I'm trying to troubleshoot it. I only have the clock signal at the output of the MN3007 and it seems pretty weird.

Does anybody knows what the signals should look like at the inputs and outputs of this chip?
Any help would be greatly appreciated!

Thank you!

Nicolas

Govmnt_Lacky · « **Reply #22 on:** August 29, 2011, 11:58:50 AM »

Quote from: omnitek on August 29, 2011, 11:52:05 AM

I installed the MN3007 on a daughter board and the pedal worked fine but it stopped working when I installed the chip directly on the main board.

I don't follow what you are saying here. It worked on the daughterboard but, you decided to install the chip directly on the vintage board?? Exactly how did you accomplish that? Did you try to "hard-wire" the daughterboard? You cannot just plug-n-play the 3007 chip in place of the SAD chip. You need the supporting circuitry of the daughterboard for the 3007 to work.

Maybe some pictures too

omnitek · « **Reply #23 on:** August 29, 2011, 12:29:01 PM »

Hi,

Thank you for replying.

Yes, I installed it on the vintage board by cutting some traces and rewiring. Not an easy job to do. I also added the other small parts.
Here's some pictures:

Govmnt_Lacky · « **Reply #24 on:** August 29, 2011, 12:35:02 PM »

Silly questions BUT.....

1) Did you account for the fact that the SAD chip ran off of V+ power (+15VDC) and the 3007 runs off of V- power (-15VDC) ?

2) Did you include ANY of the daughterboard electronics when you performed the retrofit?

3) I have read that the clocking for the 3007 is A LOT different than the SAD chip and the clock trimmer may be different. Did you account for that?

4) Have you really "dug into" the links in this thread? They have some valuable info on this retrofit.

If you figure out how to get this done, I am sure it would be appreciated if you documented the process step-by-step on this forum under a new thread. I know I would be interested!

Good Luck!

omnitek · « **Reply #25 on:** August 29, 2011, 01:30:46 PM »

Hi,

I took the Fender3D's schematics to use the vintage MXR Flanger with a MN3007
Like I said, it worked fine on a daughterboard but not when I installed the parts on the mainboard.
I included all the same components.
I checked all the information in this thread but couldn't find anything about the signal waveforms (using an oscilloscope).
It would be nice if someone could draw or take a picture of the signal waveforms we should get at the inputs and outputs of the SAD1024 or MN3007 chip.
But you're right, I think i'm gonna start a new thread.

Nicolas

Govmnt_Lacky · « **Reply #26 on:** August 29, 2011, 01:54:49 PM »

After looking at Fender3D's layout and schematic, I found a few "questions" that should be answered:

1) According to the layout, there is a TR2 listed at 100K however, there is NO TR2 in the schematic??

2) It should be noted that the Dist trim had it's value changed. On the original MXR schemo, it is 20K. On Fender3D's schemo, it is 100K (TR1)

I believe that Fender3D also stated that he had made some "tweaks on the fly" to get the circuit working. I think he is going to have to chime in here to clarify.

Fender3D · « **Reply #27 on:** August 29, 2011, 05:43:33 PM »

As per your pictures it seems you connected the Bias trim to ground instead of Vcc (pin 8 of the nearest op amp or 4013 pin 14)
Check 3007 if you have ~1V@ pin 4, 15V@ pin 1, Vbias (it will move trimming bias) @ pin 3

Fender3D · « **Reply #28 on:** August 29, 2011, 06:01:44 PM »

Quote from: Govmnt_Lacky on August 29, 2011, 01:54:49 PM

After looking at Fender3D's layout and schematic, I found a few "questions" that should be answered:

1) According to the layout, there is a TR2 listed at 100K however, there is NO TR2 in the schematic??

2) It should be noted that the Dist trim had it's value changed. On the original MXR schemo, it is 20K. On Fender3D's schemo, it is 100K (TR1)

I believe that Fender3D also stated that he had made some "tweaks on the fly" to get the circuit working. I think he is going to have to chime in here to clarify.

lol
1) I was in hurry with that pedal... I didn't breadboarded it, just drew the schematic and printed a PCB...
While drawing I remembered something about the MN's lesser signal gain (datasheets or forum...dunno), then I add the transistor before the level trimmer, but since I wasn't really sure about it I drew TR2 as a level trimmer to be used when you do not place the tranny on board.

2) TR1 is 100K

omnitek · « **Reply #29 on:** August 30, 2011, 02:46:27 PM »

Quote from: Fender3D on August 29, 2011, 05:43:33 PM

As per your pictures it seems you connected the Bias trim to ground instead of Vcc (pin 8 of the nearest op amp or 4013 pin 14)
Check 3007 if you have ~1V@ pin 4, 15V@ pin 1, Vbias (it will move trimming bias) @ pin 3

Hi,

The bias trim is connected to Vcc.
The voltages are exactly like you described.

What is weird is the clock signal (looking with an oscilloscope). It is a triangle wave with varying frequency but the amplitude is also varying a lot. Is this normal?
Thanks!

Nicolas

Govmnt_Lacky · « **Reply #30 on:** August 30, 2011, 02:54:38 PM »

Quote from: omnitek on August 30, 2011, 02:46:27 PM

What is weird is the clock signal (looking with an oscilloscope). It is a triangle wave with varying frequency but the amplitude is also varying a lot. Is this normal?

No.

Make sure that you are checking your clock signal with the Manual and Width pots fully CCW. If those pots are not all the way "off" then your clock will change.

If you have the pots set correctly, then you SHOULD see a SQUARE WAVE coming from the 4013 clock generator.

Be sure you are checking the clock at the correct pins (4013 Pins 1, 2 and 5 I believe) it should be a square wave.

Fender3D · « **Reply #31 on:** August 30, 2011, 03:23:03 PM »

Watch out, 2 wires twisted-paired kinda like your red and blue, will act like a small capacitor (few pF), maybe this capacitance adds to MN's CLin capacitance and run weird...
Try with 2 "squared" resistor "legs" or smaller wires running each other as away as possible

omnitek · « **Reply #32 on:** August 30, 2011, 07:14:04 PM »

Quote from: Govmnt_Lacky on August 30, 2011, 02:54:38 PM

Quote from: omnitek on August 30, 2011, 02:46:27 PM
What is weird is the clock signal (looking with an oscilloscope). It is a triangle wave with varying frequency but the amplitude is also varying a lot. Is this normal?

No.

Make sure that you are checking your clock signal with the Manual and Width pots fully CCW. If those pots are not all the way "off" then your clock will change.

If you have the pots set correctly, then you SHOULD see a SQUARE WAVE coming from the 4013 clock generator.

Be sure you are checking the clock at the correct pins (4013 Pins 1, 2 and 5 I believe) it should be a square wave.

Ok. Now what I've got is almost like a square wave. But the frequency is quite low. What should be the frequency of that clock?
Thank you!

Nicolas

Govmnt_Lacky · « **Reply #33 on:** August 30, 2011, 07:17:11 PM »

Quote from: omnitek on August 30, 2011, 07:14:04 PM

Ok. Now what I've got is almost like a square wave. But the frequency is quite low. What should be the frequency of that clock?

This can be adjusted to taste.

Original units (with SAD1024s) were measured by oldschoolanalog as being from 29-32KHz.

Fender3D adjusted his to around 54KHz.

It is up to you.

oldschoolanalog · « **Reply #34 on:** August 30, 2011, 08:28:24 PM »

Yes; "season to taste". After all, you are the one that has to use, play and live with it...

Govmnt_Lacky · « **Reply #35 on:** August 30, 2011, 08:41:59 PM »

Quote from: oldschoolanalog on August 30, 2011, 08:28:24 PM

Yes; "season to taste". After all, you are the one that has to use, play and live with it...

Congrats on #1000

omnitek · « **Reply #36 on:** September 02, 2011, 10:54:20 AM »

I finally found out that one trace was making contact between the clock and the output of the MN3007.
I cutted that trace and now the flanger is alive again.

It sounds great but it is a bit noisy.
There's a high pitched whine especially when the regen is at the maximum.
Is there something that can be modified to reduce the noise?
Thank you!

Govmnt_Lacky · « **Reply #37 on:** September 02, 2011, 10:59:06 AM »

Quote from: omnitek on September 02, 2011, 10:54:20 AM

There's a high pitched whine especially when the regen is at the maximum.
Is there something that can be modified to reduce the noise?

Set your REGEN to fully CW (full on) then adjust R48 (Level trim) until the point JUST BEFORE the "whine" starts to occur.

Fender3D · « **Reply #38 on:** September 02, 2011, 11:11:36 AM »

Whine will arise from:
1) too low clock freq. (check whether it happens with manual CCW, adjust clock trimmer for a higher freq.)
2) too much gain in regen path (adjust level trimmer to stop it)

Whether it is a clock noise you might add a "null" trimmer, connecting its wiper to 47k "pull up" resistor/Q1 Base and the other 2 leads, one to pin 7 and the other to pin 8 (you must separate these 2 pins first)

Govmnt_Lacky · « **Reply #39 on:** September 02, 2011, 11:20:31 AM »

Someone just asked me about MXR Flanger bloodlines

I know the Original M-117s had no LEDs on them.

I also know that the M-117Rs do have LEDs

So, my question is.... were there ever any M-117s (no R) that had LEDs?

News:

Author Topic: MXR Flanger redone (Read 52328 times)