Mesmerizer doesn't work

[stevtron]

No tremolo efx, the XR2206 LFO is veeery slow, even with max potentiometer position … What are the correct values for VDD,VCC and VREF ? I checked every part and soldering . It seems the charge pump does not work correctly. No 18V , no matter where I measure … On Vcc only 1.67 V,
on Pin4 of the XR2206 8.66 V …

 

[stevtron]

Can anyone confirm the PCB, does it work generally ?

 

[JetFixxxer]

You double check the resistor values? I had an issue with the PHASE II. After a week or so t/s w/ help from everyone here. I notice I put a 470k where a 4.7k should have been. Installed the correct value and it worked like a charm.

https://www.sparkfun.com/datasheets/Kits/XR2206_104_020808.pdf

 

[stevtron]

Sure, everything checked, double checked … thanx . I think there is something wrong with the board connections ... esp. around the TC1044 . I hope there'll some comments from the builder asap ...

 

[Robert]

Hey sorry for not chiming in sooner, it's been a chaotic week so far.

This one has definitely been built and verified. There were some quirks with an earlier revision but those should have all been canned and replaced long ago. Something definitely isn't right here though, your measurements concern me.

Do you mind pushing this one aside for a few days until I get some more PCBs in so I can check it out? If it turns out to be a PCB problem I'll send you a replacement (and credit for another one for your trouble).

 

[stevtron]

OK, sounds very fair … thank you

 

[dubelectro]

I also suffered from the same problem.
I looked at the schematic and found the cause. The anode of D6 should be connected to pin 8 of IC3 rather than pin 7.
I changed it myself and it worked properly.

 

[stevtron]

Good catch. I changed it and it solved the voltage problem. Unfortunately mine have still a lfo problem.
No tremolo/vibrato efx at all, just boosting the volume all the time. No matter where the pots are tweaked.
If yours working than I guess my XR2206 is not working properly. I ordered another one, fingers crossed .
Can you measure the voltage on pin2,3 and 4 of the XR2206 ? would be extremly helpful for me . Thanx in advance ...

 

[dubelectro]

I measured all the knobs counterclockwise. The values of pin 2 and pin 3 were slowly fluctuating.
pin2 4.10-4.76v
pin3 4.04-4.70v
pin4 8.72v

I hope this is useful for you.

 

[stevtron]

Very helpful , tusen takk ... have the same values ... so, I have the same board as yours, my IC has the same values ... whats wrong ... my search goes on ... thank you very much

 

[stevtron]

btw, the fluctuation goes up when you tweak the speed knob and the leds pulsating faster too ?

 

[dubelectro]

btw, the fluctuation goes up when you tweak the speed knob and the leds pulsating faster too ?

Yes.
The speed of the blinking seems to be in the appropriate range, and it is synchronized with the sound.
The LED is written in the Build Document as Common Anode, I think that it is a mistake of Common Cathode.
So I use Common Cathode.

Are you using TC1044SCPA?
When I made Duo-Pahse, another Charge Pump IC did not work properly.
It may be good to see using another kind of IC.

 

[stevtron]

Problem solved : It was not a wrong or defect XR2206 . It was another wrong pin connection. I changed the connection from
pin7 to pin8 and everything was fine. Strange that it works for you … case closed

Only thing is, my board looks after this mistreat like sh …

 

[dubelectro]

That’s good for you.

My XR 2206 was purchased long ago. Is it something different ...
I will review again.

 

[Robert]

I changed the connection from pin7 to pin8 and everything was fine.

Just so I understand, you did this on the XR2206 IC? If so that is quite strange!

The original definitely connects to Pin 7, but both pins are timing resistor outputs so I suppose that makes sense that it worked. I wonder why pin 7 didn't work on your IC?....

 

[zgrav]

possibly a bad chip on just the pin 7 output, but certainly a rare failure if that is the case. glad it is working now.