The Mesmerizer ( weird pedal )

I also have no oscillation with XR2206 marked F0919. I got them off eBay from some guy in the Fiji islands.

I just ordered two from Jameco.

This is the same chip the signal generator I ordered off Amazon uses. I am paying as much for the chip as for an assembled and boxed signal generator.

Todd D.
 
Got mine from China. No good! Ordering from jameco is not an option for me. I am from Manila, Philippines. $18 just for shipping.

Apparently F0919s needs to be tweaked for it to work. Anyone has any idea on how to do this?
 
Hello, I bought my second chip off Ebay, this time from a US seller that seemed to be pretty reputable. It was also a FO919 which was different from the picture, and there's no oscillation. Makes for a fantastic sounding boost, but not a tremolo, haha

Before I complain to them though, I want to make sure I haven't done anything wrong--there's like a million jfets in there, and I initially had shorted two of the legs of one of them because I forgot to trim them before I tested the PCB. Also, there is one SMD jfet, and who knows maybe I soldered that wrong.

I can post pic of pcb but is there any way to check if the IC is bad? Should I just assume that the 0919s do not work?
 
Just because the 0919s reported on here were bad does not mean that all of the 0919s are bad. maybe the bad ones we have seen are counterfeit copies of good 0919 chips.

but no easy way to test it except by putting it into a working project.

the two jeft transistors at Q5 and Q6 were the key to getting my build working. I only had 3 transistors that would work in either of those spots and that is from over a dozen or so transistors that should have worked in them.
 
I had everything working in my build except the modulation, and I knew my xr2206 chip was good because it worked in another project. The mesmerizer is a bit picky for Q5 and Q6, but I can't tell you what the magic sauce was for the ones that worked. I have since used some of the transistors that would not work in the mesmerizer in another project where they work fine.

Here is the thread where I was discussing the issues I had: https://forum.pedalpcb.com/threads/not-so-mesmerizing-mesmerizer.1225/

From your other thread, when you have the xr2206 output on the oscilloscope, does the waveform change shape when you are adjusting the rate and depth controls? You can also open the connection betwen pins 13 and 14 to turn the sine wave output into a triangle wave that has a higher output, so you could check that on your scope too.
 
zgrav said:
Here is the thread where I was discussing the issues I had: https://forum.pedalpcb.com/threads/not-so-mesmerizing-mesmerizer.1225/

From your other thread, when you have the xr2206 output on the oscilloscope, does the waveform change shape when you are adjusting the rate and depth controls? You can also open the connection betwen pins 13 and 14 to turn the sine wave output into a triangle wave that has a higher output, so you could check that on your scope too.
Click to expand...

Thanks! I'll look at your other thread and see if it helps. I don't get a shape change with rate and depth, but the frequency and magnitude do vary.
 
seems like your 0919 chip might be working.you can try opening up the connection between pins 3 and 14 to see if you get a higher magnitude triangle wave shape. my suggestion other than that would be to try multiple transistors in Q5 and Q6. You can hear a difference immediately when even one of them is working correctly.

I had a couple of J201s that worked the best, but even then most of my J201s did not work.
 
zgrav said:
seems like your 0919 chip might be working.you can try opening up the connection between pins 3 and 14 to see if you get a higher magnitude triangle wave shape.
Click to expand...
I have already swapped the 0919 for a 0918 I got from Jameco. With the 0919 there was no flickering of the LED and the wave at pin 2 was completely flat. I don't remember the voltage, but it wasn't a sine wave.
 
Do you have more transistors you can try out in Q5 and Q6? You also can order some J201 smds soldered onto an adapter board from pedalpcb for $2 each. I have some of the adapter boards on their way in the mail and plan to see if the smd 201s work in the mesmerizer.
 
zgrav said:
Do you have more transistors you can try out in Q5 and Q6? You also can order some J201 smds soldered onto an adapter board from pedalpcb for $2 each. I have some of the adapter boards on their way in the mail and plan to see if the smd 201s work in the mesmerizer.
Click to expand...

I have 6 more 2n5485 that look like they came from tayda. I have 2 more 2n5457 that came from who knows where, probably eBay. I would have to look through the rest of my transistors to see if there is anything similar, but I think they are mostly bjt. I bought some J201 recently from mammoth, but I have already used them in the Son of Ben.

I ordered some transistor sockets. I figure if I am going to be swapping out, I don't want to lift a pad re-soldering over and over.
 
Last edited:
I have read somewhere that the key to making the 0919 work is to change the input voltage(?). Oddly, when my JFET leads were shorting, I did get tremolo output from the pedal, but I also got endless honking feedback (also with tremolo effect). When I trimmed the leads, it went back to being a boost pedal ?

If there is a fix to get the 919 to work (aside from testing a million JFETs, which I don't have) I'd love to hear it!
 
Use your scope and check to see what waveform you are getting at pin 7 on IC1. Also see if it changes when you are moving the depth and rate pots. You should also be able to tell the voltage range between the bottom and top of the wave form.

that info might help others make suggestions about tweaking something for Q5 and Q6.
 
Sorry I just jumped onto an old thread, but yeah troubleshooting.

So I don't have a scope, but I am pretty sure that the 0919 from Nooelectric has pretty much the same problem as the other 0919 (but they wouldn't take it back). Anyhoo, does anyone have a good source for a 0918? I saw Jameco as one, but that's $8 plus a $5 processing fee, possibly plus shipping. Any other options? Thanks!
 
Wow ..... you guys are beating this thread into submission ... lol

I must say ... since I switched to the 0918's from Jameco this pedal has become a quick favorite of mine .... very very cool pedal .
 
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