Hey guys,
I am an audio engineer/musician who is finally wading into the technical electronics side of things. I've been meaning to do this for a while, and the right project has finally come my way.
It is a very early solid state tape echo made by a Japanese company called Elk. The device powers on, capstan runs strong and the pinch roller is in order. So, the mechanics are solid, but, as its 40 years old, the electronics need some work. I turned it on just to check the motor, but I haven't yet tried to pass audio through it, but it came to me because there was obviously some issue with it. Many of the electrolytics look bulged, so I'm going to start with a recap and go from there.
I have a basic understanding of passive electrical components. I have read plenty of articles as well as Craig Anderton's Electronic Projects for Musicians, watched tons of YouTube videos, and at my last studio there was a tech who taught me some of the basics. But, other than this, I am totally new to this world and I have tons to learn. So I'll have many questions along the way.
I need some help identifying a few things. Now, I know a capacitor from a resistor from an inductor and their varieties. But there are a couple of devices in this unit I cannot place.
First of all, what exactly is this green deal and what would it be called? It's coming right from the power transformer, and I am thinking it's just a way to move the tap of the power transformer to the other side of the case; the solenoid and motor are tapped right from the power transformer, and this green unit is where the audio power supply is tapped... I think. Am I correct in assuming the board immediately behind is the power supply board for the audio components?
Second, what is this rather sad looking paper and copper affair? It looks like some sort of rudimentary transformer.
And lastly, a few questions about this capacitor on top of the pinch roller solenoid. First of all, is this actually electrolyte leaking out of the thing??? And second, the point of the leak... well, its physically attached to the pinch roller solenoid via that little arm -- obviously I'm not going to find another cap quite like that -- so what is the work around for this?
Another view.
Yes, I know the belt is currently a rubber band!
Hopefully this post made sense and I gave enough information to answer my questions. I'm excited to be part of the community and look forward to the process! Thank you all for your time and for sharing your expertise!
I am an audio engineer/musician who is finally wading into the technical electronics side of things. I've been meaning to do this for a while, and the right project has finally come my way.
It is a very early solid state tape echo made by a Japanese company called Elk. The device powers on, capstan runs strong and the pinch roller is in order. So, the mechanics are solid, but, as its 40 years old, the electronics need some work. I turned it on just to check the motor, but I haven't yet tried to pass audio through it, but it came to me because there was obviously some issue with it. Many of the electrolytics look bulged, so I'm going to start with a recap and go from there.
I have a basic understanding of passive electrical components. I have read plenty of articles as well as Craig Anderton's Electronic Projects for Musicians, watched tons of YouTube videos, and at my last studio there was a tech who taught me some of the basics. But, other than this, I am totally new to this world and I have tons to learn. So I'll have many questions along the way.
I need some help identifying a few things. Now, I know a capacitor from a resistor from an inductor and their varieties. But there are a couple of devices in this unit I cannot place.
First of all, what exactly is this green deal and what would it be called? It's coming right from the power transformer, and I am thinking it's just a way to move the tap of the power transformer to the other side of the case; the solenoid and motor are tapped right from the power transformer, and this green unit is where the audio power supply is tapped... I think. Am I correct in assuming the board immediately behind is the power supply board for the audio components?
Second, what is this rather sad looking paper and copper affair? It looks like some sort of rudimentary transformer.
And lastly, a few questions about this capacitor on top of the pinch roller solenoid. First of all, is this actually electrolyte leaking out of the thing??? And second, the point of the leak... well, its physically attached to the pinch roller solenoid via that little arm -- obviously I'm not going to find another cap quite like that -- so what is the work around for this?
Another view.
Yes, I know the belt is currently a rubber band!
Hopefully this post made sense and I gave enough information to answer my questions. I'm excited to be part of the community and look forward to the process! Thank you all for your time and for sharing your expertise!
Hi,
1. Selenium rectifier - Wikipedia, the free encyclopedia
2. Could be the bias oscillator inductor.
3. Are any of the fixings 'thread locked'? Looks the right colour, drip gone
astray?
Chris.
1. Selenium rectifier - Wikipedia, the free encyclopedia
2. Could be the bias oscillator inductor.
3. Are any of the fixings 'thread locked'? Looks the right colour, drip gone
astray?
Chris.
Chris, thank you for your reply! I think you may be right about the thread lock solution... There are all sorts of different colors at varying points in the unit. Some threads are white, some are red, some are yellow, and some are the green. They probably represent several decades of several technicians work.
But, back to the little guy sitting on top of the pinch roller solenoid.... After further reading, I'm not sure it is a capacitor at all. The capstan motor is wired straight from the mains, into this guy, then into the motor. It's not labelled like any cap I've ever seen... Here is another pic. And also, on further review, it is not physically connected via the arm as I thought. It's just all of that green makes it seem like it is.
At any rate, all of this seems to be functional so its not tremendously pertinent, I'd just like to know what it is.
Again, thanks for the help. I know my questions are elementary for most of you guys, but you gotta start somewhere!
But, back to the little guy sitting on top of the pinch roller solenoid.... After further reading, I'm not sure it is a capacitor at all. The capstan motor is wired straight from the mains, into this guy, then into the motor. It's not labelled like any cap I've ever seen... Here is another pic. And also, on further review, it is not physically connected via the arm as I thought. It's just all of that green makes it seem like it is.
At any rate, all of this seems to be functional so its not tremendously pertinent, I'd just like to know what it is.
Again, thanks for the help. I know my questions are elementary for most of you guys, but you gotta start somewhere!
It's most likely a start capacitor for the AC motor, the wiring direct to the motor confirms it.
Mr. Chris was right on the rectifier (ancient selenium type - I replaced hundreds of them with silicon ones back when they were in use), and he's also correct about the bias oscillator transformer.
It's a pretty poorly built looking unit though, typical of old Japanese construction methods.
It would be helpful to know the numbers on your mystery motor cap. it may be OK anyway.
Why NOT try to run signal through it? it may help reveal work needing to be done, and it also might reveal things that are working and need no work.
As others said, the green stuff dripped on your mystery cap is just goo, but not from the cap.
If the tape transport works, then check power supply through the audio circuits. See if it passes signal. In order to record - needed to make echo - you heed to have the bias oscillator running, so scope around that sloppy coil to see if there is a STRONG oscillation going on. I don;t know what this one runs at, but I'd expect something in the 100kHz region, give or take a wide margin.
Why NOT try to run signal through it? it may help reveal work needing to be done, and it also might reveal things that are working and need no work.
As others said, the green stuff dripped on your mystery cap is just goo, but not from the cap.
If the tape transport works, then check power supply through the audio circuits. See if it passes signal. In order to record - needed to make echo - you heed to have the bias oscillator running, so scope around that sloppy coil to see if there is a STRONG oscillation going on. I don;t know what this one runs at, but I'd expect something in the 100kHz region, give or take a wide margin.
Enzo, thanks for your reply. I've learned quite a bit already from reading your posts in other threads...
I will pick up an oscilloscope tomorrow and start scopin!
So would this inductor be coupled with a cap as part of an LC Circuit?
Thanks!
I will pick up an oscilloscope tomorrow and start scopin!
So would this inductor be coupled with a cap as part of an LC Circuit?
Thanks!
Yes, it's a transformer (not just an inductor), and it will be part of an oscillator circuit with the value of the transformer and the associated capacitor setting the frequency (which will be supersonic).
Here's a fairly standard type of transistor circuit:
http://www.palsite.com/bias_osc2.gif
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