Author Topic: Noise help with a flanger  (Read 1993 times)

Govmnt_Lacky

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Re: Noise help with a flanger
« Reply #15 on: August 22, 2019, 10:50:01 AM »
You need a 7815 or 78L15 regulator after the charge pump, whatever you're powering it with, put that in and see how you get on before doing anything else.

Sweep is Speed so yes it should be C500k.

To add to Scruffie's post... and to clear up any possible confusion...

You need to install a LM7815 onto your Road Rage PCB. The pictures you provided do not show one being installed. So, you are NOT getting 15VDC regulated from that board. You need to install one of these:


TNblueshawk

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Re: Noise help with a flanger
« Reply #16 on: August 22, 2019, 12:29:19 PM »
It finally hit me after Scruff's second post. The word "Doh" came to mind with a forehead slap. I plan to do all these things on my long weekend. I'm off work tomorrow.

Thanks to both of you and I'll report back.
John

TNblueshawk

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Re: Noise help with a flanger
« Reply #17 on: August 26, 2019, 09:16:36 AM »
So as it turns out, I should never rely on memory at work, I was running it at 18v and that is the reason I didn't put in a regulator. I'm using an old Road Rage board which corresponds with Bean's 2012 build doc.

So I figured let me rewire for 15, add a regulator and see what happens. Well. when I did that all I got was this huge hum and the pedal pretty much didn't work any longer or I could just barely make out an audible swoosh but he hum is so loud, even with guitar volume off, I have to shut the pedal off or something like my speaker might blow! So because of this hum and my lack of time this weekend apparently I didn't bother with shielding the wire yet. I did put in a C500k Speed pot though.

So, I ran out of time to fiddle around. How about if I punt and start from scratch here and I'll work up a new RR board to power this thing.

If you were me would you run this thing at 18v no reg per the RR BOM or 15 with reg? Also, the correct orientation of the 7815 was where the metal backing would lay flat on the RR board (I made sure it didn't so as not to touch the SAG control eyelets), correct?

Out of curiosity, would running it at 9v be such a bad idea I wonder?
John

Govmnt_Lacky

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Re: Noise help with a flanger
« Reply #18 on: August 26, 2019, 12:26:30 PM »
The original MXR Flanger ran at 15VDC (regulated internally)

According to the datasheet for the SAD, the MAX operating voltage is 20VDC however, the MAX clock voltage is 17VDC  :-\ Now, I do not know if that means 17V for EACH clock input or 17V to be split in half for each individual clock input or 8.5VDC

Either way, I would recommend that you go for the 15VDC option to stay true to the original design.

TNblueshawk

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Re: Noise help with a flanger
« Reply #19 on: August 26, 2019, 01:07:23 PM »
The original MXR Flanger ran at 15VDC (regulated internally)

According to the datasheet for the SAD, the MAX operating voltage is 20VDC however, the MAX clock voltage is 17VDC  :-\ Now, I do not know if that means 17V for EACH clock input or 17V to be split in half for each individual clock input or 8.5VDC

Either way, I would recommend that you go for the 15VDC option to stay true to the original design.

So with the RR board I just want a second opinion on this. When installing the regulator I want to make sure I have the right pinout. I read the data sheet on the 7815 but I'm not settled on where pin 1 is on the RR board. My reading of it is that when installing the metal back of the 7815 would lay flat (again I won't flatten it) on the RR board, correct? As opposed to the plastic 'box' laying flat on the board.
John

Govmnt_Lacky

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Re: Noise help with a flanger
« Reply #20 on: August 26, 2019, 01:13:15 PM »
So with the RR board I just want a second opinion on this. When installing the regulator I want to make sure I have the right pinout. I read the data sheet on the 7815 but I'm not settled on where pin 1 is on the RR board. My reading of it is that when installing the metal back of the 7815 would lay flat (again I won't flatten it) on the RR board, correct? As opposed to the plastic 'box' laying flat on the board.

If you have a multimeter, just make sure the 15V out on the RR board is connected to Pin 3 of the 7815 regulator (Vout)

EDIT: From what it looks like in the build doc, you can add the regulator tab down on the component side of the PCB (I would add a buffer material so the tab does not touch any exposed pads) and you will also have to install C6 (10uF)
« Last Edit: August 26, 2019, 01:22:29 PM by Govmnt_Lacky »

TNblueshawk

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Re: Noise help with a flanger
« Reply #21 on: August 28, 2019, 06:32:35 AM »
Just to update the thread I replaced the Road Rage board and the pedal worked with minimal or I guess normal noise. While I can't pinpoint why in looking at the old RR board as it looks good apparently there was an issue on that board. But in a comical moment, one has to laugh at times, I had 2 of the SAD chips so I wanted to test the second one. I pulled the chip out and noticed that pin 16 of the socket pulled up. Never had that happen before. I pushed it back down wondering if the socket was buggered up. I put the chip back it and of course nothing works. Dead quiet when I kick the pedal on. I said one has to laugh right?

So I guess I'll desolder a 16 pin socket. This should be fun. Hope I don't jack up the board doing this. I suppose I could attempt to solder in the pin that is not connecting but then all kinds of bad crap could happen. I could solder it in with of course chip in there and it still doesn't work. I could burn out the chip maybe, dunno.

Who says this hobby isn't fun  :o
John

TNblueshawk

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Re: Noise help with a flanger
« Reply #22 on: September 01, 2019, 10:41:31 AM »
Well it was going so well desoldering the socket for the SAD then pin 16 I lifted the trace. Or, that was the issue the whole time as that was the pin in the socket that got all floppy jawed on me. So, per the data sheet it calls this pin NC and says it should be connected to ground.

If you guys were me and you wanted to make this work as opposed to tossing the board what might you rig for this lifted trace?
John

Govmnt_Lacky

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Re: Noise help with a flanger
« Reply #23 on: September 01, 2019, 12:21:17 PM »
So, per the data sheet it calls this pin NC and says it should be connected to ground.

Well, if you want to get literal... there are several pins on that board that are NC and should be connected to ground according to the datasheet. Best advice would be to look at the schematic for the original and see what they did with those pins. From what I can see of original PCB pics from the MXR, it looks like they did tie NC pins to GND.

TNblueshawk

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Re: Noise help with a flanger
« Reply #24 on: September 01, 2019, 01:45:22 PM »
In the body of the data sheet it says the NC's should go to ground. I'm just trying to figure out how I could rig something to where the IC works and Ive tied that pin to ground. I was thinking I could solder a wire in on pin 16 with the socket and the IC but then that IC will have to stay there given I'm soldering it in. The down side, assuming that would even work, is I can't test the other chip. Of course I do have a second board as Haberdasher etched me two but I hate to ditch this board if somone has a more ingenious way of saving it.

Question. I assume I can ground that anywhere or do I have to tie it into the board?
John

Govmnt_Lacky

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Re: Noise help with a flanger
« Reply #25 on: September 01, 2019, 02:00:06 PM »
If it were me...

I would use my Dremel to drill a hole into the large ground plane closest to Pin 16 and another hole right next to Pin 16. Install a jumper on the component side of the board. Solder one side of the jumper into the ground plane. Solder the other side of the jumper directly to Pin 16.

You are still leaving Pins 4, 13, and 16 as NC though...  :-\