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 (http://www.aronnelson.com/gallery/main.php/v/MarkMs-Gallery/album15/album76/Dreamey_Creamer_LAYOUT.gif.html)
Thank you soooo much!
Matt
Check R17, and a schemo would be nice...
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?
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...
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.
Gotta find my multimeter then.... where the heck did I put it :icon_redface:
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?
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.
Sounds "Farty"?
http://www.geofex.com/fxdebug/bias_prob.htm (http://www.geofex.com/fxdebug/bias_prob.htm)
Quote from: solarplexus on December 15, 2008, 07:41:36 PM
Gotta find my multimeter then.... where the heck did I put it :icon_redface:
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)
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?
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?
Could it be that Q4 is backwards on the layout?
No, they all have the same pin to ground.
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?
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...
Pete, I think you have missed that there is no DMM... :icon_wink:
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... (http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=22046&g2_serialNumber=1)
..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.
Quote from: DougH on December 16, 2008, 11:34:17 AM
Pete, I think you have missed that there is no DMM... :icon_wink:
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... (http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=22046&g2_serialNumber=1)
::) -Yeah, I know. Way to much spare time!
Well, you don't have near as much apparent spare time as someone like me who is just watching... HA! :icon_mrgreen: :icon_wink:
Ok well guys just forget it instead of being blastered just because I happen to have lost my DMM I'll just stay quiet. :icon_rolleyes:
Thanks for those who helped.
Dude look. Without a DMM there's very little anyone can do for you. That's just a basic tool you need for debugging electronics. It's like trying to work on your car without a wrench, or build a house without a hammer. You will only be able to go so far.
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=90899
Sometimes they go on sale for even less. Good to have a few one in the car or truck and one in the house. You might not want to leave a fluke DMM etc in the car.
Yupp...I get 'em for 3.88 at Marcs Discount stores, best deal ever on anything AFAICT.
Just set it aside until you can aquire the absolutely necessary tool...
I tried to build a (close to) CD spec'ed Muff once and had the same problem. But I, having a DMM, was able to check the transistor bias. :) It went something like this:
Q1: ~4.5V
Q2: ~4.5V
Q3: ~4.5V
Q4: ~0.7V ???
After triple checking that everything was the correct value and that there were no bad solder joints I did the math and this did make sense. Maybe it was because I was using BC239s instead, but the 390 emitter resistor was just way too low. I replaced it with a 3.3K I think and it ended up working fine. Then again since 390 is in the schematic and I'm sure tons of people have built this successfully I may be compensating for a different error I made.