MXR Micro Flanger Debugging

[seten]

I have a mxr micro flanger that passes signal whether its on or bypassed but its completely dry either way. All my previous experience debugging has been with pedals that just dont pass signal so I'm not sure where to start. I briefly poked around with an audio probe and couldnt find a wet signal anywhere but I didnt check every single component on the board. Checked to make sure all four IC's had power where the schematic said V+ but I'm not sure what the other pins on the ICs should be at to see if theyre operational or if thats even where I should be focusing on.

Also, might have blown something up - I was checking to see if the transistors had power and when I put the red lead on my dmm on one of the pins I heard a pop and smelled a electrical burning smell. Any ideas what that wouldve been and how I could avoid it in the future?

Also, heres the schematic but I cant find a picture of where all the components are on the actual circuit board so if anyone has one that would be wonderful.

https://s304.photobucket.com/user/candletears/media/Micro20Flanger-11_zpsc45ce547.jpg.html

IC Voltages:

U1 (TL062)
1 - 4.1v
2 - 4.1v
3 - 3.5v
4 - 0v
5 - 3.8v
6 - 4.1v
7- 4.1v
8- 9.4v


U2 (MC14069UB)
1- 0v
2- 6.9v
3- 0v
4- 9.2v
5- 0v
6- varies consistently (i think from 0.01-0.4v? hard to tell but I can try harder if its necessary)
7- 0v
8- 9.3v
9- 9.4v
10- 6.9v
11- 9.3v
12- 9.3v
13- 9.3v
14- 9.4v


U3 (SAD152) - written on schematic as A3? Upside down V3?


1- 6.8v
2- 0v
3-
4-


each time i check 3 and 4 theyre at a different voltage i think between .5 and 1 volt, and its changing very very slowly.


5- 9.4v
6- 1.9v
7- 0v
8- 9.4v


U4(TL061CP)
1- 0-0.05v (seems to be inconsistent)
2- 2.5-6.5v (varies consistently)
3- jumps between 2.5v and 6.6v
4- 0v
5- 0v
6- 8.6v
7- 9.2v
8- varies around 0v (goes a little negative up to about 0.1v)


had a hard time locking down the results for U4. might just be incomptency but for example I couldve sworn I was consistently getting 2.5v on pin 7 but now its giving me consistently 9.2v so I went with that.

[seten]

Added IC voltages

[Fender3D]

4069 is not working ok...
pins 2-4-6 should be ~Vcc and pins 8 to 12 should have clock for BBD (then ~1/2Vcc)

[Govmnt_Lacky]

4069 is not working ok...
pins 2-4-6 should be ~Vcc and pins 8 to 12 should have clock for BBD (then ~1/2Vcc)

Perhaps the 4069 is installed the wrong way?

[Mark Hammer]

I have two Micro-Flangers.  One of them went belly-up and Mike Irwin was able to diagnose it for me and restore it to good health by installing a new 4069.

I will also note that the plastic-enclosure Commande series used lousy PCB-mount switches.  So if yours is one of that generation, keep an eye out for the switch.

[seten]

Thanks yall! I'll try getting a new one in there and see if thats the ticket.

[seten]

are all hex inverting chips with 4069 in the name interchangeable? mine says MC14069UB, what do the mc1 and ub mean?

[Mark Hammer]

I may be wrong but I don't think there are buffered and unbuffered types, as there is with 4049 invertors.

[duck_arse]

"MC1" would indicate that it was a motorola part, or a manuf using the motorola part numbering style - UB indicates nothing at all in this case, as all 4069's are unbuffered. well, we are yet to find an example of a datasheet claiming a buffered part.


[edit :] "MC5" would prolly indicate it came from Michigan.

[Mark Hammer]

My bad.  When I said I didn't think there were buffered and unbuffered types, what I meant was that I didn't think there were buffered 4069s, distinct from the unbuffered variety.  Thanks for clearing that up, duck.  Always good to prevent wild goose chases wherever possible!

[seten]

Gotcha - thanks so much yall! Kick out the jams.

[seten]

Got a whole new set of voltages on the new 4069 but still doesnt work. Same thing, always passes signal but its always dry.

New voltages:
1- 0v
2- 9.4v
3-  0v
4- 9.4v
5- 0v
6- 9.4v
7- 0v
8- 0v
9- 9.4v
10- 0v
11- 9.4v
12- 9.4v
13- 0v
14- 9.4v

Any ideas? I put it in the same way as the original one - I didnt socket it unfortunately so I cant easily see if its in the wrong way but the original did not looked replaced/messed with at all so I doubt that was the case.

Actually, just remembered - i thought the little indent and the dot are supposed to be on the same side and thats pin 1/pin14. On the 4069 I got from tayda the indent is on the opposite side as the dot so I assumed the indent takes priority as the pin 1 side. Was that correct?

[duck_arse]

please to be humouring me, and post some photos of the offending circuit board.

also, so it is here for next time, please be observing:


the "half moon" is the pin 1 end notch. pin 1 is to its left. also note the pin 1 pip, next to pin one. can also be seen on that body, two moulding indents/ejector pin marks - these are indicative of nothing, except that the part has come from an injection moulding process.

old mate:


here see above: pin 1 end notch [right thru], pin 1 pip, and moulding mark, of no interest.

the ti way:


no pin 1 end notch, no uninteresting moulding marks, only a single shallow pin 1 pip, which might look like an ejector mark, but isn't.

here's a trick:


showing an uninteresting moulding indent where pin 1 should be, and a pin 1, part thru, end notch where you might expect an uninteresting etc.

so, perhaps also post a photo of your part, see if we can identify all the dings. hope something here is helpful.

[Fender3D]

4069 is not working ok...
pins 2-4-6 should be ~Vcc and pins 8 to 12 should have clock for BBD (then ~1/2Vcc)

[seten]

please to be humouring me, and post some photos of the offending circuit board.

also, so it is here for next time, please be observing:


the "half moon" is the pin 1 end notch. pin 1 is to its left. also note the pin 1 pip, next to pin one. can also be seen on that body, two moulding indents/ejector pin marks - these are indicative of nothing, except that the part has come from an injection moulding process.

old mate:


here see above: pin 1 end notch [right thru], pin 1 pip, and moulding mark, of no interest.

the ti way:


no pin 1 end notch, no uninteresting moulding marks, only a single shallow pin 1 pip, which might look like an ejector mark, but isn't.

here's a trick:


showing an uninteresting moulding indent where pin 1 should be, and a pin 1, part thru, end notch where you might expect an uninteresting etc.

so, perhaps also post a photo of your part, see if we can identify all the dings. hope something here is helpful.

Will post pics when I get home from work - so in that last picture the end notch is marking the pin 1 / pin 28 side correct?

I guess I'll just replace 4069 again but I'm gonna wait until I get these sockets in. Is tayda known for stocking unreliable 4069's / IC's in general?

[seten]

Pics : http://imgur.com/gallery/U0oYo2N

[duck_arse]

here's a trick:



showing an uninteresting moulding indent where pin 1 should be, and a pin 1, part thru, end notch where you might expect an uninteresting etc.

- so in that last picture the end notch is marking the pin 1 / pin 28 side correct?

ahh, possibly that last was a gag gorn rong - if you rotate the IC in that pic by 180 degrees, yes, pin 1 / pin 14 notch.

I'm not sure the problem is with your 4069, as it seems to be doing what it's been told. the problem may well be further back, perhaps the oscillator IC or one of the transistors between that and the 4069.

[Govmnt_Lacky]

Unless you are trying to resell this pedal, I would recommend that you remove the 4069 and put a socket in there. When you add the socket, leave the 'new' 4069 out and read out the contacts with a DMM. Make sure there are no shorts.

Seems to me that your problem is either a shorted contact -OR- like Fender3D said before.... a run of bad IC chips. 

[Fender3D]

4069 in your pics is placed correctly...
Yet, you do not get any clock on pins 8-9-10-11-12-13 as per your voltage chart.
Check you didn't broke the small 50pF cap....

[Govmnt_Lacky]

Check you didn't broke the small 50pF cap....

Or.. possibly shorted/bad. Would explain why you have Vcc on Pins 9, 11, and 12.