MOOG Etherwave Plus LED redirect?

Hello. Very excited to be a new Theremin owner and enrolled on the Lydia Kavina master class next month. I have one minor technical issue though with the Theremin….

I have just built up my MOOG Etherwave Plus Kit… All appears to works ok, but unfortunately the job was made incredibly difficult because my soldering iron was horrific. During the build I accidentally fitted the LED on the wrong side of the board. In trying to de-solder I damaged the pcb contacts the LED connects to. So… I now have a light that doesn’t work and nothing to solder it to. Is there somewhere else on the PCB that I can wire it so I can get the light to work?

I can live without a light, but it would be nice to have. Thank you

Simon

Use a glass fiber pencil to eliminate the green varnish from the copper stripes which go to the damaged LED contact points until they are blank. Take a good and fine soldering iron, tin the blank copper first and then solder some 0.3mm diameter silver plated copper wire on it to make new contacts with the LED pins. You can't connect the LED to other points of the PCB since it gets its current limited through a 1k smd resistor somewhere on the PCB.

You'll most probably have to take the Plus board out again to perform the operation. 

I know it's too late, but good irons don't cost that much.  I'd love to own a Metcal, but I'm using a Weller WES51 that I bought for $90 off Amazon that's not bad, and there are similar irons out there for less like the WLC100 for $42, and perhaps some of the off-brands like AOYUE.  I prefer the ones with a manual dial for the temperature, rather than the ones with digital displays and up/down buttons.  The WES51 shows via a blinking LED when it's up to temp (~30 seconds) - I believe it shows directly the PWM going to the element which is kind of neat.  Temperature regulated irons are the best and tend to have fairly short heat up times.

Hi Simon,

I am near Eastleigh / Winchester (SO50 6FX) - about an hour from Oxford (where Lydia is).. Would be more than happy to re-solder your LED or whatever for no charge if you drop bye and wait while I repair it.. If interested, my email is my avatar

(I might even be at Lydias next class if I can make it - Could probably bring an iron etc and fix it there - Depends if I am fit to drive and get a car by then..)

<-----

Fred.

OT - Soldering irons..

ps - I have found Antex soldering irons to be the best low cost (£15 ish) irons for general use - when AND ONLY when fitted with the narrowest bit - They are available from Maplin (30W)

But soldering irons are extremely personal! - Most people love Wellers, but I hate them, Antex is deemed cheap and hobbyist, but I love them - And have their most expensive thermostatic workstation with 2 irons (£150+now - I paid about £50 ).. But for many years was happy with the cheap ones. I have used several other "stations" in the £300+ price range and found them all inferior to the antex. Have had my Antex station for perhaps 30 years now, re-fitted the controller into a new box caus it dropped  - but the original irons are still in use, all I ever need to replace is the bits.. Same is true for the cheap mains irons - still have my originals (40 years old?)... Not sure if theyr made so well these days though.

"I prefer the ones with a manual dial for the temperature, rather than the ones with digital displays and up/down buttons. " - Dewster

Absolutely agree! _ my Antex is exactly as you describe your Weller..

[at present im negotiating design of a thermostatic portable iron using an E-Cig battery - bought this superb E-Cig which has an in-built  MCU controlling charging  and user settable  voltage or wattage, and senses the coil resistance - realised that this could make it ideal for a soldering iron which could normally be run from a 5V supply in "feed through" mode (simultaneously keeping its 1AH lithium battery charged), but would also be portable.. so contacted the manufacturer...] .. The volume of these being made has brought their retail price down to under £30..

Sadly, the inteface is digital, and I wont be able to change that..

Ok.. well thank you everyone. I'll go with the glass fibre approach to get a new contact. Maybe see you there Fred.

P.S I've been to Eastleigh many times. It's where Europe's best corps in the elite marching band world was from  - http://www.senators.org.uk . Great times, although they're rebuilding now so not the power house they once were. Totally the wrong forum for this talk though ;)

"Totally the wrong forum for this talk though ;)" - frysers

LOL ;-) .. After a while at TW you may discover that threads tend to go off topic, and usually this is fine!

My personal attitude is that a thread like this, dealing with a narrow topic which is resolved in a few posts, is free game - To me, one of the really nice things about TW is that threads which would otherwise be "closed" tend to wander off in all sorts of interesting directions..

The above is my personal opinion, I dont know the opinion of other members or moderators - But I think Jason is inclined to let things wander more than is tolerated by many forums, and that he shares at least some of my feelings with regard to the value of the diversity this relaxed attitude encourages.

Im fairly sure that if he didnt, he would let me know - I certainly hope he would! ;-)

Fred.

" You can't connect the LED to other points of the PCB since it gets its current limited through a 1k smd resistor somewhere on the PCB." - Thierry

This is true - but there is nothing to stop one from adding a series 1k resistor to a LED lead, and connecting it to any on-board supply point..... But I do agree that leaving it as it should be is by far the best route.. 

BTW: You'll find your Etherwave Plus operating more stable without the LED... Yes, it "only" draws 10mA which will not raise the circuit's power consumption above the limited output current of the integrated voltage regulators, BUT it will drive their power dissipation much closer to their limits! Normally you have around 19V at their input and 12V at their output, thus the 78L12 will have to eat up 7V... times 10mA that makes additional 70mW to transform into heat. Thus the 78L12 will heat much more up and the theremin will need a longer time to become stable after powering on. And I observed that even when fully heated up, the tuning of the Plus is much more sensitive to the ambient temperature.

There is a simple fix: Don't connect the LED there where it should, but take the +19V at the big capacitor before the integrated voltage regulator, let it go through a 1k8 resistor to the anode of the LED and connect its cathode to ground (the other wire of the big capacitor). You can pull the needed two wires twisted below the main PCB between the fixed pitch and the volume oscillator without affecting their tuning. This will give you the advantage of a power indicator LED without the resulting problems of the Plus circuit design.

There is a simple fix: Don't connect the LED there where it should, but take the +19V at the big capacitor before the integrated voltage regulator, let it go through a 1k8 resistor to the anode of the LED and connect its cathode to ground (the other wire of the big capacitor). You can pull the needed two wires twisted below the main PCB between the fixed pitch and the volume oscillator without affecting their tuning. This will give you the advantage of a power indicator LED without the resulting problems of the Plus circuit design. - Thierry

Thierry, does this apply also to the Etherwave Standard?

I was thinking of adding a power LED to my Etherwave: it's good to have an indication of when it's on or off and my first thought would have been to connect it to ground and an on board supply point via a load resistor as Fred suggested above.

"And I observed that even when fully heated up, the tuning of the Plus is much more sensitive to the ambient temperature."  - Thierry

Oh lord, this is making me seriously rethink using Bourns 6300 parts in my stuff.  I suppose it's time to somehow characterize them in terms of temperature with the stone age equipment I've got laying about.  *Sigh*

There is a simple fix: Don't connect the LED there where it should, but take the +19V at the big capacitor before the integrated voltage regulator, let it go through a 1k8 resistor to the anode of the LED and connect its cathode to ground (the other wire of the big capacitor). You can pull the needed two wires twisted below the main PCB between the fixed pitch and the volume oscillator without affecting their tuning. This will give you the advantage of a power indicator LED without the resulting problems of the Plus circuit design. - Thierry

Thierry, does this apply also to the Etherwave Standard?

I was thinking of adding a power LED to my Etherwave: it's good to have an indication of when it's on or off and my first thought would have been to connect it to ground and an on board supply point via a load resistor as Fred suggested above.

It's basically the same in the Etherwave Standard, but thanks to the missing Plus circuitry, an additional LED will not drive everything onto the limits, thus reducing thermal and stability impact. It's nonetheless a good idea to use the unregulated voltage for the LED and keep the regulated one for the oscillators.

The  procedure is the same, it's just from another point of the circuit board and with a resistor of a little higher value.

Personally, I prefer replacing the power switch with one which has an integrated LED. They are available for around 4€ and you can choose between a red or a green LED. This is easier to install and does not require drilling an additional hole in the front panel.