Dynacord Echocord tape delay problem

[junkmanistan]

HELLO!

I just picked up a Dynacord Echocord Mini on eBay but need some help getting this thing to work properly. Anyone have any experience with these things?

After reconnecting the wires to the motor fuse and replacing the power jack with the standard 3-pin computer cord type, I thought I was ready to go. The motor runs, I can get a nice, clean guitar sound thru both inputs and I can here the echo functioning on some level when I turn the echo feedback pot to the right of the power button all the way up; this gives a lot of feedback, the speed of which (time between echoes) can be altered by sliding the playback head along the bar (much like an echoplex I assume?).

HERE'S MY PROBLEM: for some reason the incoming signal from either input is not being sent to the echo effect, as in even when I turn the echo volume up, all I get is increased background noise (I'm guessing this knob works in a 'send signal to echo' type routing?) but no taps or echo of what's being played!? Since I can get echo feedback I'm at a loss as to where the system has broken down...

Lemme just say that I'm not overly technically inclined, I don't have the schematic (though I may order a copy) and I'm not too good with a multi-tester.

Any help would be greatly appreciated!

[junkmanistan]

no one, huh?

[junkmanistan]

damn....

[junkmanistan]

Weeeelllllllllllllll, I've made a little headway with this and have run into an issue that I'm hoping someone who's a little more electrically inclined could help with.

After cleaning and demagnetizing the heads AND replacing the tape loop (shiny side out) I realized that the signal from the input IS reaching the record head. THe problem is that the echo is only audible when the input volume for the instrument is jacked up really high. Since this pot acts as a kind a preamp, the signal gets real distorted, which sounds pretty cool, but I'd like to be able to get a clean signal to hit the echo as well.

What I don't know is whether, when the input volume is set low enough to keep the instument signal clean, the signal is actually hitting the tape enough to create an audible echo BECAUSE THERE'S SO MUCH NOISE WHEN i TURN THE ECHO VOLUME UP! With the echo volume all the way down (and even with the instrument volume all the way up) there is very little noise. The overwhelming amount of noise in the echo volume doesn't sound to me like just tape noise; it sounds like there's something amiss in the circuit....

Any idea what this might be? I've heard that in guitar amps failing or 'leaking' capacitors can cause a lot of noise. My noise is crackly and generally pretty nasty....

[???????]

Your record level is too low. Not enough signal is getting onto the tape.

On the echoplexes, there is a little trimpot that allows you to set the record level.

It looks like there might be a trimmer next to the red DIN jack on the back (little screwdriver head). Try cranking that all the way to the right (or left) and seeing if that makes any difference.

Also, make sure the tape is traveling right over the appropriate spot on the record head. Sometimes something is out of alignment and the record head is only recording on the very edge of the tape.

But i'd bet a dollar it's the record level trim adjust, and I'd bet an additional 50 cents that it's right there to the right of that red DIN jack.

[junkmanistan]

Strangely enough, I've played with that little echo level knob a lot and it doesn't seem to have any effect....

After working a little more with this machine I realized that the effect IS working even at low instrument levels. It's just that the noise is so loud and overpowering that I couldn't tell at first. It sounds to me like the noise is actually being put to tape as well. Like I said before, the noise is introduced as you turn up the echo volume, but disappears if you turn the motor off. This would seem to indicate that the tape mechanism is making the noise, but it's just so much noise that I can't see how it could just be the noise of the tape running over the heads.

[???????]

what kind of noise is it, hiss, buzz, hum?

You might consider re-capping it. Have you cleaned the tape heads and travel path?

Does this thing have dark brown carbon composition resistors in it? It probably does (most old audio gear does). Sometimes those will get humidity in them and make a hissing noise if they are in the audio path.

If you have played with the trimpot (screw head next to the red DIN jack) and it didn't do anything, it might be tech time unless you are comfortable opening it up on your bench to check out the problems.

[???????]

if you can post a clip of the noise I might be able to tell you if it sounds like carbon-comp resistor noise.

[djimbe]

What is your signal chain? Lotta these old tape delays are instrument level devices, meant to go between a guitar and an amplifier. If you're using them as effects devices during mixing, make sure you feed them an instrument level signal. An impedence matching device will help send mixing board outputs to the delay in an appropriate fashion so you don't overload the input side. Sounds like you just plugged a guitar into it, so you're good there.
They output side of old delays often like to hit a line amplifier of some kind before a console. Any mic preamp that has a good DI will work fine. The outboard amp brings up that missing echo level of yours without freaking the machine electronics out.

How you trying to use that thing? Could be the source of some of your problems...

[junkmanistan]

My chain is just guitar straight into the input (same results with both inputs) and out the black DIN on the back into a solid state practice amp. I don't get any audible signal coming out of the red DIN...?

Anyway, this thing is really starting to piss me off, cuz here I am about ready to record this awful noise when something strange started to happen: the noise started to vanish in slow, weak waves. The only problem was that the echo effect went with it! So now I'm back to where I started: little to no audible echo no matter how high I jack the instrument input level and the echo level, and no matter what I do with the little "level control for echo" pot on the back. The only echo effect I get at all will be described below....

First, just to reiterate, I just thoroughly cleaned the heads and tape path the other night and demagnetized the heads. I also replaced the tape loop with a barely used piece of tape. After doing all this I was actually able to hear the echo for the first time, but it was buried under a large amount of whooshing noise that got louder as I turned the echo volume up (the knob to the left of the power and motor buttons).

One thing I notice, now that the noise is gone, that might be relevant to this mystery is the effect that the connecting tape that holds the splice together is having on the echo signal. Because it's not a perfect splice, every time it runs over the head on the far left (when looking down on the machine a la the pic above) it gives off an audible bump sounds that gets the echo treatment. This is all pretty quiet even with the echo volume jacked all the way up. The echo time can be changed by sliding the other head (the one on the slider of course). Also, if you crank the echo feedback knob (to the right of the buttons) you can get tons of feedback that can be changed by sliding the head.

WHAT COULD ALL THIS MEAN! Let me say again that I really don't understand tape machines. What head does what? Maybe if I could wrap my brain around that I could figure out what the problem is!!!

[???????]

what kind of tape is on there? Like what formulation? Is it high output tape like 456, or what? If it's a formulation that wasn't around when the thing was designed it might not work properly.

Sounds like you might be in need of a cap job my friend. If you shake the unit around does it have any effect? If so, it might just be a loose connection somewhere.

[junkmanistan]

I'm using old but unused Ampex 341. Basically NOS. I shook shook shook the thing but I didn't hear any change at all....

Here's a link to me chopping at my guitar at different settings on the Echocord:

download

It starts out with the instument level and the echo volume all the way up, hence the guitar is distorted. You can hear the echo very faintly in the background. I change the echo times around a little bit here. I had to keep the recording level pretty low here due to the high instrument level.

Next, I turned the instrument level down to around '2' so the guitar was still clean and I turned the echo volume all the way up. The echo pot inroduces all the hum. I turned the recording level up a good deal for this. As you can hear, there's no audible echo effect. I turned the echo volume on and off so you can hear the amount of noise it introduces.

Then, I turned the echo feed back all the way up and the echo volume down (not fast enough, as you can hear the clips) and played with the echo time slider so you could hear the feedback.

Lastly, I turn the feedback off and take the echo volume up and down in a sullen reprise of that crappy echoless hum....

SOOOOOOOooooooo, any ideas?

[???????]

That hum sounds like a 60 hz. hum. That indicates to me that something is weird in the power supply. Somehow a DC ripple current isn't getting properly filtered, I would guess. CAP JOB TIME.

Then get back to us.

[junkmanistan]

WHAT I FEARED MOST! Unfortunatly, I've never actually jumped into something like this, schematic in hand. I wouldn't even know what caps to test or replace. Any advice on where to even begin looking, maybe using the pics up top as a reference? When you say 'power supply' would that have anything to do with the power cord jack I replaced? Something with the tranny?

Thanks again!

[???????]

I think that the caps in question are probably the gold foil-encased ones that are off on their own board, the ones that the twisted yellow/black pair of wires is running across in the pics. These things can pack a whallop, as in store a charge after the unit is unplugged and shock the shit out of you. Even kill you if the voltage they store is high enough (probably isn't anywhere close in the case of this solid-state device, but still dangerous). You should do some reading about 'how to discharge electrolytic capacitors' before you mess with it. It's really easy to do a cap job, just a few connections... but make sure you use quality caps and install them with correct polarity, and adhere to all safety guidelines (though, as I said, I would bet that the risk is relatively low of getting hurt with this unit, especially if you were to leave it unplugged for several days before starting).

If you're new to this and doing work yourself, I recommend you take digital pictures of all components you are going to replace BEFORE YOU START so you have a guideline in case you forget what goes where (cap polarities, etc). To replace those caps, you probably wouldn't need a schematic. Just get the correct values and drop 'em in.

It may fix your problem, and may not. In either case, it's definitely time to do it (routine maintenence is considered a cap job ever 10-15 years for amps, echo units, and the like) and it will probably improve performance, and maybe even clear up that hum problem.