525 build thread

[janczmok]

Okay, i need some help on debugging this baby.

It's powered up, the LED is green and i am getting audio thru the module (when IN/OUT is not pushed).
As soon IN/OUT switch is pushed, LED is red and i have a lot of static noise, literally it sounds like an Amp, but without input signal.
None of the controls have effect in either in/out. when powering up the Module (or power down) i get a short burst of signal on the LED's, so
i can assume i soldered them correctly.

Jumper set on TERM and on the MODE.

Any idea where to start debugging ?

 

[benlindell]

Check for voltage getting to the 2520s.

 

[peter purpose]

Any idea where to start debugging ?

Did you do the A4 mod?

 

[janczmok]

Did you do the A4 mod?

which mod is this ? I did add the C3 in between the attack pot. Also i added the small wire on the add-on board
and also cut the two tracks and rewire the resistor on output.

 

[Sredna]

I think he means the mod described on page 3, posting nr 43.

The PCB of the small upright DOA had an error, its an easy fix....

 

[peter purpose]

I think he means the mod described on page 3, posting nr 43.

The PCB of the small upright DOA had an error, its an easy fix....

Datsdawunn

 

[janczmok]

Dawunn was made. Loong ago.
so... i'll try to check the 2520's then.

 

[duantro]

Good new is that I've got my pair built and squashing!
Still debugging a few things though.... ???
First: It appears that I have my switch wired up incorrectly. When I look at the Schematics in the BOM it appears that r64 goes from sw5B pos20 to ground. On this other wiring diagram that was posted Later in this thread, it states that r64 goes between ground and sw5A pos 20. I'm assuming that since my switch isn't behaving and I wired it up blindly by the second diagram, that it is indeed incorrect? Should ground go to SW5A pos 0, and r64 go from SW5A pos 0 to SW5B pos 20?

Here's the second diagram that I'm referring to:

Quick wiring dagram.
This does not mean I'm back..!!

Large version...
http://www.twin-x.com/groupdiy/albums/userpics/525wiring.jpg

 

[peter purpose]

Do it as in the schematic and you'll be dandy.

 

[duantro]

Thanks, I think I have it squared away now. I just nailed r64 from SW5b pos 20 to SW5a pos 0 (ground). seems hunky dory
Now just have to figure out why the led meters aren't lighting.

I wanted to add that this thing sounds amazing! Pretty versatile unit from the small amount of use that I've had with it so far.

I also Highly recommend the attack mod that DMP posted. It gives you plenty of adjustment range.

 

[Sredna]

I also Highly recommend the attack mod that DMP posted. It gives you plenty of adjustment range.

Hmmm, so it does work after all?

 

[duantro]

Yes it works great with plenty of adjustment. You can even get it to pump pretty good for an aggressive sound. I'm using the Omeg 1 Meg pots (thanks kazper).

I also Highly recommend the attack mod that DMP posted. It gives you plenty of adjustment range.

Hmmm, so it does work after all?

 

[JBVries]

Anybody have a Mouser project built with this the BOM?

 

[duantro]

Can anyone verify that the LED meters actually work to some degree with this design? I can't get any of them to light up with normal audio signal, but can with more voltage applied. It seems that there is too much resistance somewhere.
It appears that I have a bad Omeg input pot on one as it bypasses the compression if you futz with the pot shaft. Anyone source these in the states or is this only over seas?
Everything else is working great.

 

[dmp]

The LED meters definitely work and can be adjusted to be very sensitive. Have you adjusted R55? This trimmer sets the level going to the meter.

 

[duantro]

The LED meters definitely work and can be adjusted to be very sensitive. Have you adjusted R55? This trimmer sets the level going to the meter.

Yes I have adjusted r55 all the way up and still no LED's. I'm not sure what is going on.....

I'm very interested in your mod that you recommended from the "new" 525 thread:

About adding a FET to the meter circuit, I had this in mind. I didn't try it on a breadboard (which would have to be done) but it looks good when I plotted out the voltages.
Similar to a 1176, a second FET mirrors the one in the audio path. Both FETs would share the same cv, so you wouldn't need the meter path on the original schematic anymore (cr3, cr4, r53, r55, c12, r54,r68,cr6).
Since the resistance of the FET is loglinear with cv, the meter voltage from this divider has to go to a log scaled (dB) LED driver. Since you want to see GR steps, something like the LM3915 since it gives even dB increments.
I couldn't figure out how to change the fullscale range on the LM3915 this morning, however. 30dB fs is more than needed. Maybe it could be adjusted or a different chip would give the range you want...

I've ordered all of the parts to try this, just waiting on the LM3915's to show up. Hopefully this will fix my issues along with being an improvement with the LED scaling.
Thanks again for your input DMP, I'm appreciating the attack mod along with the audio ground mod's. : thumbs:

 

[JBVries]

I like to order extra Parts and there may be some completely unrelated parts on here, but here is an already existing, mostly built mouser order.

Just check it against your BOM right quick and it should have you a little closer to being on your way to a 525..... ;D

http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=2fdd070592

 

[peter purpose]

duantro,
Maybe daft, but is the chip fitted on the underside?

 

[dmp]

And maybe the LEDs are in backwards, try flipping one and see if it goes on.

 

[dmp]

I've ordered all of the parts to try this, just waiting on the LM3915's to show up. Hopefully this will fix my issues along with being an improvement with the LED scaling.

Cool! Good luck experimenting.