# Pedal Help Needed - MXR Micro Flange



## The Usual

I just finally found a flanger I like. I bought a 1970s MXR Micro Flange off Kijiji and it sounds great. It had a 9v battery in it, and it has no adapter port. So I was using a 1 spot 9v battery clip. I hooked it into a radio shack 9v universal adapter with what I thought was the correct end. Long story short, it was a loud hum, and now it doesn't work, even with the battery. I am very peaved, as I normally don't like flange. Anyone know..

Someone in near London who can fix a pedal
What normally goes in a pedal with the wrong power applied to it? I always thought the wrong adapter, would fry the adapter, not the pedal.

I could really use some help


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## mhammer

PM me, I have a schematic for it.


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## 2manyGuitars

mhammer said:


> PM me, I have a schematic for it.


You know...
you should just make that your sig. :smile:


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## mhammer

2manyGuitars said:


> You know...
> you should just make that your sig. :smile:


As it is, there are plenty who think it IS my sig. I try not to tempt fate *too* much.:smilie_flagge17:


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## shoretyus

mhammer said:


> As it is, there are plenty who think it IS my sig. I try not to tempt fate *too* much.:smilie_flagge17:


Gee Mike you know how to break the stuff too?


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## mhammer

Even better. I know how to break it *while* I'm fixing it.:smile:


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## The Usual

mhammer said:


> PM me, I have a schematic for it.


Pm'd you. Thanks.

Man I am soo bummed out about this. I really like the sound of this pedal. I hope I can get it back. Here are a few pics for those interested.


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## mhammer

I have one of these: http://www.pedalarea.com/images/mxr_flanger_commande_01.jpg which is essentially the same flanger with different (worse) switching, a plastic box, and maybe a few other cosmetic differences. It's actually a nice crisp flanger. Let's hope the SAD512 is not fried because they are hard as hens' teeth to find and generally very expensive when you can land one; easily worth more than the flanger itself. If the BBD is not fried, and we can get it working, I'll point you to some nifty mods.

Here is the schematic.








I'm not seeing the 1N270 diode on the board you show. I'm not seeing the LED either, so it could be that the schematic is labelled as yours but is actually mine. No big whoop, it's the same effect circuit. HOWEVER, I'm not seeing any trace of a protective diode in case of power mishaps like you described. Of course, since there was no power jack, they obviously didn't need to include such a diode....or at least didn't anticipate what you would do.

Step 1, take the SAD512 out of the socket and stick it in conductive foam for safekeeping. Now we can dicker with the rest of the circuit.

The CD4069 chip is a CMOS chip which is static sensitive (although so is the 512), and can fry easily. My own flanger was nonfunctional precisely because of that chip. Once the chip was replaced, it was right as rain.

So, once you have the BBD safely out of the way, you will want to connect a 9v battery and see if you can get 9v (or thereabouts) on pin 8 of the TL062, pin 7 of the TL061, and pin 14 of the CD4069. If you don't get that reading, something is amiss.

In view of how cheap they are to replace, and likely it is that it was fried, get yourself some solder wick and desolder the CD4069. If you can score a low profile socket, install the socket and pop a fresh CD4069 in there. Now re-do your voltage readings. If the read good, then unpower, pop the SAD512D in the socket, cross your fingers, and fire it up.

We'll take it from there.


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## The Usual

mhammer said:


> I have one of these: http://www.pedalarea.com/images/mxr_flanger_commande_01.jpg which is essentially the same flanger with different (worse) switching, a plastic box, and maybe a few other cosmetic differences. It's actually a nice crisp flanger. Let's hope the SAD512 is not fried because they are hard as hens' teeth to find and generally very expensive when you can land one; easily worth more than the flanger itself. If the BBD is not fried, and we can get it working, I'll point you to some nifty mods.
> 
> Here is the schematic.
> 
> 
> 
> 
> 
> 
> 
> 
> I'm not seeing the 1N270 diode on the board you show. I'm not seeing the LED either, so it could be that the schematic is labelled as yours but is actually mine. No big whoop, it's the same effect circuit. HOWEVER, I'm not seeing any trace of a protective diode in case of power mishaps like you described. Of course, since there was no power jack, they obviously didn't need to include such a diode....or at least didn't anticipate what you would do.
> 
> Step 1, take the SAD512 out of the socket and stick it in conductive foam for safekeeping. Now we can dicker with the rest of the circuit.
> 
> The CD4069 chip is a CMOS chip which is static sensitive (although so is the 512), and can fry easily. My own flanger was nonfunctional precisely because of that chip. Once the chip was replaced, it was right as rain.
> 
> So, once you have the BBD safely out of the way, you will want to connect a 9v battery and see if you can get 9v (or thereabouts) on pin 8 of the TL062, pin 7 of the TL061, and pin 14 of the CD4069. If you don't get that reading, something is amiss.
> 
> In view of how cheap they are to replace, and likely it is that it was fried, get yourself some solder wick and desolder the CD4069. If you can score a low profile socket, install the socket and pop a fresh CD4069 in there. Now re-do your voltage readings. If the read good, then unpower, pop the SAD512D in the socket, cross your fingers, and fire it up.
> 
> We'll take it from there.


Thanks so much. First queston. What is conductive foam? Can I not use any foam.


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## The Usual

Starting to wonder if I am out of my league. Or rather, realize.
How do I know pin is which? I can't read schematics. 
I assume that the SAD512 is the BBD?


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## geckodog

Out of curiosity, was the adaptor you used an AC Adapter or DC?


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## keeperofthegood

The Usual said:


> Thanks so much. First queston. What is conductive foam? Can I not use any foam.












Conductive foam is just that, foam that conducts electricity. It is a static safeguard. You can do a couple things in case you don't have any, 1 being using tinfoil and pushing the pins into a piece of that so they are all shorted. I am not 100% (Mark may know) but if you have one of the silvery grey plastic bags like what video and sound cards come in, you can also put the chip in that.


When dealing with static parts, you also want yourself grounded. Usually just putting a hand onto a water tap is a good quickie to use too, just be sure to put the drain plug in the sink when you do this 




The Usual said:


> Starting to wonder if I am out of my league. Or rather, realize.
> *How do I know pin is which?* I can't read schematics.
> I assume that the SAD512 is the BBD?


I will assume you mean pin 1. Pin 1 is always indicated differently from all the other pins. In the pic I put up there, pin 1 is the dimple. The pins are numbered in order from 1 down that side, then up the other so:

1o--- 8
2 --- 7
3 --- 6
4 --- 5


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## mhammer

Yes, the SAD512D is the BBD.

A few words about it. Normally, delay chips require inputting complementary clock signals. That is, one line is tic when the other is toc, and vice versa. This requires either using a specialized clock generator chip like the MN3101 or MN3102 (used with all the MN3xxx delay chips that Panasonic/Matsushita used to make), or another - usually 4xxx-series CMOS - chip to produce a "flip-flop" action. That is, the clock-generator circuit will output two complementary clock pulses to step the delay chip through its actions.

The SAD512D was "special" in that it contained the circuitry to derive the complementary pulses by dividing down a single high-frequency clock pulse (kind of like an octave divider, only much much higher). This is part of what allows it to provide such a compact board. The CD4069 chip (and only part of it is even used) provides the high-frequency clock pulse, and the SAD512D does the rest.

The Matsushita chips, like the venerable MN3101/MN3007 pair or MN3102/MN3207 pair used to produce countless thousands of flangers, had an inherent flaw. And that is that at the sort of clock frequencies needed to produce really dramatic flanging, their interaction would sort of crap out, such that it was near impossible to get delay times of under 1 msec with any real fidelity or reliability. If one stuck a "buffer" chip between the MN310x and MN3x07, it was possible to overcome this hurdle and generate ultra-high clock frequencies that worked, but this meant another chip and a bigger board footprint. The Reticon chips (SAD512, 512D, 1024 and 4096) came already prepared to handle much higher clock frequencies, so it is no surprise that many of the most desirable flangers use Reticon chips. The Matsushita chips (and their subsequent replacements) are excellent chips, but their Achilles heel is that they don't do ultra-short delays particularly well without a lot of help.

Unfortunately, what all of this has meant is that if the 512D chip is blown, there is really no other chip on the market that would substitute for it easily. And we're not even talking about a pin-for-pin sub here. We're talking about something that could be put on a "daughterboard" with some pin reroutings, some header pins, and stuffed into the existing socket. Nope, replacing the 512D with anything else on the market that might conceivably sub for it in terms of function would require several chips and basically an overhaul of the Micro-Flanger clock circuit. Which is an awful lot of work and would not even guarantee the same sound for all that work.
*
DO NOT LET THIS DETER YOUR EFFORTS TO RESTORE THIS PEDAL*. It is entirely possible that the problem may be minor and the fix relatively trivial and well within your capabilities with a bit of on-line guidance.

For now, we simply need to know if the power from a battery is still going where it was supposed to and how it was supposed to.


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## The Usual

mhammer said:


> Step 1, take the SAD512 out of the socket and stick it in conductive foam for safekeeping. Now we can dicker with the rest of the circuit.
> 
> The CD4069 chip is a CMOS chip which is static sensitive (although so is the 512), and can fry easily. My own flanger was nonfunctional precisely because of that chip. Once the chip was replaced, it was right as rain.
> 
> So, once you have the BBD safely out of the way, you will want to connect a 9v battery and see if you can get 9v (or thereabouts) on pin 8 of the TL062, pin 7 of the TL061, and pin 14 of the CD4069. If you don't get that reading, something is amiss.
> 
> We'll take it from there.


So I took out the BBD carfely, grounded on the sink and into an electrostatic bag. I had one that one of my computer parts came in.

I put a 9v battery in, and set the multimeter to DCV. Black probe went to the black - socket on the battery, and the red probe went to the positions you listed above. I assumed pin 14 on the CD4069 was across form the pin with the 1 in front of it. No dimple on this one. I got the same reading on all pins. 7.08, which I assume is a half dead 9v battery. 

So, am I jumping ahead to assume that the BBD is fried? Hope not, because I looked on line all day, with not a lot of luck.


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## mhammer

Well, again, before we accept some bitter truth about the BBD, let's consider other options. If your meter will do AC voltages under, say, two volts, then plug your guitar in to the pedal (with the SAD512D still removed), strum, and measure the AC voltage at pin 1 of the TL062. It should probably be around maybe 500-800mv or so. Now measure the AC voltage at pin 7 of that same chip. It should also be around the same level as pin 1.

Now measure the DC voltage at the junction of R30 and R31. Really and truly, it is an AC voltage, because it changes, but since the change is rather slow, we'll use DC to be able to note its changes. You should see the voltage rising and falling as the LFO sweeps back and forth.


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## keeperofthegood

The Usual said:


> So I took out the BBD carfely, grounded on the sink and into an electrostatic bag. I had one that one of my computer parts came in.
> 
> I put a 9v battery in, and set the multimeter to DCV. Black probe went to the black - socket on the battery, and the red probe went to the positions you listed above. I assumed pin 14 on the CD4069 was across form the pin with the 1 in front of it. No dimple on this one. I got the same reading on all pins. 7.08, which I assume is a half dead 9v battery.
> 
> So, am I jumping ahead to assume that the BBD is fried? Hope not, because I looked on line all day, with not a lot of luck.



This site lists one version available http://www.vintageplanet.nl/semiconductors.html

Not sure if it is the chip you need, or not though. I used ctrl-f to find it on the page.


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## The Usual

mhammer said:


> Well, again, before we accept some bitter truth about the BBD, let's consider other options. If your meter will do AC voltages under, say, two volts, then plug your guitar in to the pedal (with the SAD512D still removed), strum, and measure the AC voltage at pin 1 of the TL062. It should probably be around maybe 500-800mv or so. Now measure the AC voltage at pin 7 of that same chip. It should also be around the same level as pin 1.
> 
> Now measure the DC voltage at the junction of R30 and R31. Really and truly, it is an AC voltage, because it changes, but since the change is rather slow, we'll use DC to be able to note its changes. You should see the voltage rising and falling as the LFO sweeps back and forth.


You guys are awesome. How do I know the pedal is on? Do I plug it into the amp and leave it on the dead setting? Unplug it from the amp, then do the test? Or is there a way to use the mm to figure out the on position? And do I need a cable in the out jack during the test? There's no LED on this bad boy. Also, where are R30 and R31 physically located?


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## mhammer

keeperofthegood said:


> This site lists one version available http://www.vintageplanet.nl/semiconductors.html
> 
> Not sure if it is the chip you need, or not though. I used ctrl-f to find it on the page.


There were two SAD512 chips: the D and the not-so-D. The D version (used in the Micro-Flanger and a number of other commercial products from both MXR and DOD, to name a few) was 8-pin and included the flip-flop dividing circuitry on-board. The not-D version was 16 pins and was actually an SAD1024 with only one half of it guaranteed to work. It did NOT include the on-board dividing circuitry and had to be fed a pair of complementary clock signals. The one will not sub for the other, and sadly, the linked-to site lists the D version as out of stock.

How will you know the pedal is "on"? I can't see the photos each of us posted at the moment because they are blocked at work, so I have to work from memory of the schematic. The stompswitch is wired up such that the common lug goes to the output jack. One of the outside lugs takes its feed from a couple of passive componentas traceable back to pin 1 of the TL062 (a so-called "buffered bypass"), and the other takes its feed from a couple of passive components traceable back to pin 7 of that same chip, after the wet and dry have been mixed together. 

In a sense, the pedal is always "on", but the bypass switch selects its feed from one of two different points in the circuit. This means that what you need to measure can always be measured, regardless of the status of the switch. That's a good thing.


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## The Usual

Got it. I will test away tonight after work, and post the results.


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## The Usual

mhammer said:


> If your meter will do AC voltages under, say, two volts, then plug your guitar in to the pedal (with the SAD512D still removed), strum, and measure the AC voltage at pin 1 of the TL062. It should probably be around maybe 500-800mv or so. Now measure the AC voltage at pin 7 of that same chip. It should also be around the same level as pin 1.
> 
> Now measure the DC voltage at the junction of R30 and R31. Really and truly, it is an AC voltage, because it changes, but since the change is rather slow, we'll use DC to be able to note its changes. You should see the voltage rising and falling as the LFO sweeps back and forth.


Took a crack it this last night. I set the MM to ACV and put the black probe on the black part of the battery clip, and the red on pin 1 and 7 on the TL602. They both read .001 v. I don't know if that is usefull. 

I didn't measure the junction of R30 and R31 because I don't know where that is on the board. I know it's hard to do, but can you describe which resistors these are?


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## keeperofthegood

Hey oh

-1 on that site listing chips eh  bummer that, but maybe there is still hope out there.

If you did get the pins 1 and 7 correct, then you should have power across them or from the battery to them.

As to R30 and R31, going by the schematic Mark posted, R30 is a 1 meg resistor, and R31 is 150 k. Looking it all over, it appears there are only two 1m and two 150k resistors and only the one point where they tie together. They are also drawn beside the TL061 so that is where I would suggest starting to look for them, or following from pin 2 of that chip. Helps in sorting them out, the photo is too off for colour and texture to make seeing them easy (photos of pc boards are not easy to take). The colour code for them are:

1 Meg is Brown Black Green tolerance_band
150 K is Brown Green Yellow tolerance_band

I cannot see the tolerance_bands in your photos, they are either Silver or Gold (actually looks like both may have been used), this band is usually offset a little bit and is on the right of the rest of the bands.

http://www.csgnetwork.com/resistcolcalc.html these kinds of tools are handy until you can just look are read off the values.


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## The Usual

Do you think they would typically orient all the resistors the same way? The ones that are parallel of course? It seems like mine have gold and silver bands on them. But the all definatley have gold.


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## The Usual

Actually if you can zoom in on the photo, the 2 resistors under the caps labelled 103 and 151 next to TL061 are the only ones that have a green band next to a gold one. If gold is my tolerance band (as it seems to be common to all of them) then these can only be the ones that are 1 meg. Am I on the right track so far?


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## The Usual

The Usual said:


> Actually if you can zoom in on the photo, the 2 resistors under the caps labelled 103 and 151 next to TL061 are the only ones that have a green band next to a gold one. If gold is my tolerance band (as it seems to be common to all of them) then these can only be the ones that are 1 meg. Am I on the right track so far?


Scrap that. There are 2 others I just noticed. This blows.


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## The Usual

Here's not much better photo


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## keeperofthegood

North of the two transistors on the right, there is a tantalum cap bent over a resistor. Is that resistors colours

RED BLACK YELLOW GOLD

It looks to me there is only one 200K resistor on the schematic, and one side of that ties to R30/R31


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## mhammer

I'd participate at this point, but I can't see the pictures.


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## keeperofthegood

mhammer said:


> I'd participate at this point, but I can't see the pictures.


It's ok I think Mark, work restrictions are just life 

I am wondering how true the schematic you posted is to the circuit being worked on? Well, the evening is only a few hours away


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## mhammer

As near as I can tell, the principal difference between the two pedals is the inclusion of a status LED and the use of a different switch and box. The kind pictured here - http://www.effectsdatabase.com/model/mxr/commande/stereoflanger - is the one I have and it uses a small soft-touch DPDT switch on the board itself that is actuated by a plastic plunger. The one shown here - http://www.effectsdatabase.com/model/mxr/m152 - would appear to be the one in the schematic, and for whatever reason, the one owned by The Usual lacks the DPDT switch and accompanying status LED, and seemingly the protection diode.. I gather it is the model just before the 152. The 2000 series - http://www.effectsdatabase.com/model/mxr/2000/flanger - is a slightly different circuit.


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## The Usual

Sorry guys but I'm at work too, and I need to go home to check those colours. Mine does not have an LED and the switch in it is the same Carling one from a regular Dunlop wah pedal if that helps.


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## The Usual

OK so I am back at home looking at this. Can I use a mm on either side of the resistors and find 150 and 1megs, or is this an improper way of measuring resistors in a circuit? I'm a little lost on mine, because nothing is connected to pin 2 on TL061. Entirely possible I'm reading this wrong, but I am taking pin 2 as to the right of the pin next to the dimple. It is soldered to the board with no trace over/under the board.


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## keeperofthegood

Well, this is in part how I do this:










Definitely need a clearer photo to list them all, and I am SO not sure on some of the colours in the photo too. However, this is where I suggest starting from.

And it may look that the 61 and 62 chips are reversed? Maybe? Or there was production run changes to the values?? OR someone loaded the wrong values in when making it? OR I am just not seeing it too 

OH YEA I put a Red Dot on every IC pin 1


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## The Usual

You are the man. How do you type over a photo? Did you do it in paint, or photobucket? I can use your legend and just give you them all if that helps.


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## keeperofthegood

HAHAHAHA

Thanks XD Photoshop yea, I started off in IrfanView but it was too imprecise for this.


What would be needed is a photo with the disk capacitors set upright so the resistors are not blocked under them. Then all the resistors can be listed off. Because of the nature of light and colour I expect visual errors but those can be checked against listing with the colour legend. I didn't make Green Gn or Grey Gy because I should have >.< it was a "oh d'oh" moment but I have the original all in layers so Grey bands can be used and distinguished from Green later. 

HOWEVER:

I am hoping Mark will be able to have a look at the board at this point and spot either similarities or differences. Certainly pin 2 of the TL061 suggests some difference from the schematic. It just could be that there was some design changes from your model to the model commonly encountered on-line and you have the dubious distinction of adding information to the Internet that did not previously exist


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## keeperofthegood

MARK!

Ok, I found the data sheets and I see, the D designation has the internal D-Flip-Flop ok!

http://en.wikipedia.org/wiki/Flip-flop_(electronics)#D_flip-flop

http://www.experimentalistsanonymous.com/diy/Datasheets/SAD512-1024.pdf

http://www.experimentalistsanonymous.com/diy/Datasheets/SAD512D.pdf

It could be doable with an smt d-flipflop and the SAD512 with a daughter board as you have said. Placement would be the hard part, I would mount it upside down, chip facing circuit board and use a surface mount Dff to save space. Other than grounding out unused inputs and sections, I don't see any side parts needed (no resistors or capacitors) otherwise.  need someone with circuit cad to lay it out.


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## The Usual

Does this help at all?


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## The Usual

or this


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## keeperofthegood

lol

The first worked ok. There are still colour points in question and a covered part or two but we are closer on this first level of mapping:


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## The Usual

Thanks for all the work! Any ideas on where to measure this thing? I can't read schematics, but something isn't lining up for me. 061 pin 2 goes nowhere. 062 pin 2 goes to some Rs and Cs and ends up at pin 7 of 061. On the schematic, I don't see pin 7 062 anywhere. In short, I am lost.


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## mhammer

Actually, now that I have a better picture to work from (thanks!), pin 2 does go somewhere. It just does so out of plain sight. The trace from pin 2 to the .01uf feedback cap comes out from under the chip on the component side. You can see a trace escape out from between pins 1 and 8 to the .01uf cap. That cap connects back to pin 6, as per the schematic.

Tucked under the .01uf cap that was laid down flat in the first picture you posted is a 150k resistor. You can see in the better picture that the 150k has a trace that runs out to near the edge of the board, and just under the end of those two electrolytics sits a 200k resistor. Anywhere along the trace between the 150k and 200k we should be able to measure the LFO output.

The only problem is that, with .001v on pin 7, it seems you aren't getting any supply voltage to the chips. Just to be absolutely certin, did you measure the voltage with a good battery in and a plug inserted into the input jack? Remember that no power will be supplied to the circuit until there is something plugged in to the input jack.


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