Danelectro Dan Echo self oscillation problem, no mods on it HELP!

[Jonathan Vortex]

Hi Guys, I need some help, got this Danelectro Dan Echo Delay, the thing is that it has self oscillation, but never made or has mods, can it be fixed?

[vigilante397]

...can it be fixed?

Yes

Welcome to the forum We're going to need a loooooooot more information to get you taken care of, but the short answer is yes, I'm sure it can be fixed.

[Jonathan Vortex]

great! what kind of information do you need?
pictures?
a video?

https://youtu.be/Jel6kr0QDPQ

[Jonathan Vortex]

by the way, how can I insert images? I can't haha

[vigilante397]

This is a very good place to start: http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

If you can get us voltages on the ICs and transistors that will help a lot, a schematic will help, and of course pictures will help. The best way to post them is to upload them to an image hosting site (I personally use imgur) and post the link here using BBCode (which imgur gives you as an option) or by clicking the "Insert Image" button and pasting in your link.

My opinion on the video: I don't really view it as a problem. There are plenty of commercially available delays out there (MXR Carbon Copy, Way Huge Aqua Puss) that can get self-oscillation with the feedback turned up. When I build delays (usually Deep Blue clones) I like to include a switch to get self-oscillation.

So if you like the self-oscillation I would suggest leaving it, if you don't like it there will be a resistor you should be able to swap out (that's why we need the schematic ) that should get rid of it for you.

Hope this helps!

EDIT: I just did a quick google search and couldn't find the schematic, but if you can get a reasonably clear picture of the circuit board we should be able to figure something out for you.

[vigilante397]

Another quick note (because why not? It's only midnight ) it looks like R10 is the resistor in question. Some units have it attached, which should give fairly tame repeats, some owners have reported that one side of it has been clipped or disconnected from the factory, removing it from the circuit, which would allow infinite repeats and self-oscillation. Is your R10 resistor connected to the circuit board on both sides? If not, connect it and see if that fixes the problem. If so, what resistance value is it? We should be able to tweak that resistance to get you into the repeats range you're looking for.

[Jonathan Vortex]

[Jonathan Vortex]

https://www.dropbox.com/s/mnp42vknn9wb61a/Dan%20Echo%20Schematic.pdf?dl=0

[vigilante397]

This is the main one I needed to see. Below the "repeats" pot there is a resistor labeled R10. That's the guy we need. It's hard to tell from the picture whether it's a 1.5k or a 15k, but the schematic says it's supposed to be 15k. Can you make out the colors of the stripes? It should be Brown-Green-Orange, but it kinda looks like Brown-Green-Red.

Either way, the next step is going to be swapping that guy out for a different resistor. Is that something you're comfortable doing?

[Jonathan Vortex]

ok! I'll do that, as soon as I get a multimeter and a soldering iron, thanks very much, I'll let you know what happened