Dreamy Creamer debug help

solarplexus · December 15, 2008, 04:33:58 PM

Hi guys,

I'm building another Dreamy Creamer (lost my old one). I built it using Markm's layout (same as the old one) but I'm having problems with it. I only have an audio probe to test it. It sounds farty, and at the middle of the tone pot, there is no sound (or barely audible) at all when plugged in my amp. With the audio probe, Q4 is what is giving me the problem. I have replaced it, same thing. It is the top pin (if you look at the layout... sorry I forgot what is the exact pinout) that gives the fartiness. I used 4 2N5089 and I replaced the 561pf with 330pf (that's the only thing I had available). The rest is all regular parts. I believe it is somewhere in the tone stage that gives me problems.... could you help me out plz??

http://www.aronnelson.com/gallery/main.php/v/MarkMs-Gallery/album15/album76/Dreamey_Creamer_LAYOUT.gif.html

Thank you soooo much!

Matt

oskar · December 15, 2008, 04:56:13 PM

Check R17, and a schemo would be nice...

solarplexus · December 15, 2008, 06:52:45 PM

I replaced R17 with another, same problem again. Sorry I don't have any schem and can't find one anywhere. What could it be?

oskar · December 15, 2008, 07:22:08 PM

Don't go changing components you brute!
Finesse, s'il vous plait!

You first FIND the error, and then you correct it!

When I say check it means...

1. Look at it
2. Meditate upon it
3. Cup of coffe
4. Wiggle it... perhaps
5. While at it go over resistance values ( for instance R19 )

You can temporarily hook up another resistor in parallel to see if you can get some action from it.
Like the tone pot. It's fishy right? When it's in one of it's extreme positions the resistance should be 0R so short two lugs with some wire. Just wrap thin, bare wire around them. If it's still the same then it wasn't the tone pot.

Get a multimeter! They're so cheap...

R.G. · December 15, 2008, 07:28:18 PM

There is really little else you can do except easter-egging in parts and re-re-re-re-inspecting solder joints, wiring and parts values.

It's essentially impossible to debug any further without a voltage measuring device of some kind.

solarplexus · December 15, 2008, 07:41:36 PM

Gotta find my multimeter then.... where the heck did I put it

solarplexus · December 15, 2008, 07:44:40 PM

When I switched the 470K resistor with a 330K resitor, I had to strum real hard to get a sound out of it.

Where should I look (along with the Q4 of course) with the multimeter?

bean · December 15, 2008, 07:56:48 PM

I've built that and had the same issue. I haven't gotten around to debugging it. I did trace the layout and it seemed to be okay compared to the schematic its based on. I think there was an extra cap in somewhere around Q3...I'd have to look at it again.

oskar · December 15, 2008, 10:06:27 PM

Sounds "Farty"?
http://www.geofex.com/fxdebug/bias_prob.htm

drewl · December 15, 2008, 10:29:12 PM

Quote from: solarplexus on December 15, 2008, 07:41:36 PM
Gotta find my multimeter then.... where the heck did I put it

You lost the other pedal, now you can't find your meter?

Maybe try building a GPS in this one.

Any caps in backwards? (electrolytics of course)

solarplexus · December 15, 2008, 10:36:27 PM

No electrolytic caps in this one...

If I read right from RG's article... it would mean that the base is getting too much voltage with R17 (470K) so I should increase the resistance?

oskar · December 15, 2008, 11:55:59 PM

Quote from: solarplexus on December 15, 2008, 10:36:27 PM
No electrolytic caps in this one...

If I read right from RG's article... it would mean that the base is getting too much voltage with R17 (470K) so I should increase the resistance?

Well, didn't it just get worse when you decreased it?

solarplexus · December 16, 2008, 06:39:56 AM

Could it be that Q4 is backwards on the layout?

oskar · December 16, 2008, 06:45:47 AM

No, they all have the same pin to ground.

oskar · December 16, 2008, 06:56:11 AM

Quote from: solarplexus on December 15, 2008, 10:36:27 PM
If I read right from RG's article... it would mean that the base is getting too much voltage with R17 (470K) so I should increase the resistance?

Did you try increasing R17?

petemoore · December 16, 2008, 11:21:48 AM

DMM: Clip black lead to Gnd.
Red lead on
Emitter [note Voltage
Base [voltage
Collector [V
might as well look at all four transtors biases...

DougH · December 16, 2008, 11:34:17 AM

Pete, I think you have missed that there is no DMM...

These guys are basically trying to debug a circuit problem over the internet with no voltage measurements, via trial & error.

Oh well, it's fun to watch...

petemoore · December 16, 2008, 11:48:11 AM

..yep , I saw RG's post so decided not to cast my vote.
I saw something about voltage on a resistor and figured maybe a reading was taken..
@@ rate..clippin' that black to Gnd. and testing out your EBC bias's on all four Q's...always good to check the score potential with your new team.
Hafta say DMM.
Close in light and mag glass arent' bad, good when they find 'it', with connections required, and no ability to test connections or potentials...it's like playing "find the one red ball in the ballroom with the lights out.

oskar · December 16, 2008, 02:08:34 PM

Quote from: DougH on December 16, 2008, 11:34:17 AM
Pete, I think you have missed that there is no DMM...

These guys are basically trying to debug a circuit problem over the internet with no voltage measurements, via trial & error.

Oh well, it's fun to watch...

-Yeah, I know. Way to much spare time!

DougH · December 16, 2008, 03:42:44 PM

Well, you don't have near as much apparent spare time as someone like me who is just watching... HA!

News:

Dreamy Creamer debug help