Dropped it. Solder joints look fine. Don't know where to start. Any suggestions?
Broken Gakken Theremin
Posted: 4/27/2010 9:34:17 AM
Make sure the battery is in place and that the leads from the battery connector are in place.
Make sure the speaker leads have not broken off.
Take a magnifying glass and check the circuit board for any broken solder joints or broken traces.
A broken gakken is a sad thing. Hope that you can bring it back to life.
Make sure the speaker leads have not broken off.
Take a magnifying glass and check the circuit board for any broken solder joints or broken traces.
A broken gakken is a sad thing. Hope that you can bring it back to life.
Posted: 4/27/2010 12:18:38 PM
already tried all that. i have a multimeter, is there anything i can test?
Posted: 4/27/2010 8:37:59 PM
Unfortunatly, no. No noise, nothin. None of the components seem that delicate. All the solder joints are glued. It stumps me b/c it looks like it was built well.
Posted: 4/28/2010 8:02:49 AM
Well, I'd start with the power supply. I'd just follow the traces on the PCB and make sure that power is being delivered. Make sure that the on/off switch is working ok. The other technique would be to use the continuity tester on your DVM and check every trace and connection for continuity.
It is possible that the coils' internal leads broke -- they are very thin. If the coils are broken, then the oscillators won't work and, of course, no sound will come out.
You might be able to use a frequency-counter (if your DVM has one) to see if the oscillators are working (you probably can detect oscillation at one of the coils' leads).
It is possible that the coils' internal leads broke -- they are very thin. If the coils are broken, then the oscillators won't work and, of course, no sound will come out.
You might be able to use a frequency-counter (if your DVM has one) to see if the oscillators are working (you probably can detect oscillation at one of the coils' leads).
Posted: 4/28/2010 11:18:52 AM
Bringing an AM radio in close proximity and tuning it close to the theremin's frequency is an easy thing to try.
At the theremin's carrier freq, the AM radio will be very silent ... since the theremin's carrier is much stronger than any radio stations far away.
The usual culprit on, shall we say, "inexpensive Asian-made" gear, is cold soldering connections. The classic cold solder connection is dull and lumpy ... but not all cold solder connections look like that.
Try "touching up" all the solder connections ... or try a section at a time. Don't over do it! You may need to add a tiny bit of new solder to get good flow. Also too much flux can cause weird problems ... particularly in high impedance circuits like LC oscillators. Take a cotton swab dipped in isopropyl alcohol (the 90% rubbing alcohol variety)and clean off all the flux around all the soldering connections. Then dry this off by patting with a dry cloth. It may take a few tries to get it all off.
At the theremin's carrier freq, the AM radio will be very silent ... since the theremin's carrier is much stronger than any radio stations far away.
The usual culprit on, shall we say, "inexpensive Asian-made" gear, is cold soldering connections. The classic cold solder connection is dull and lumpy ... but not all cold solder connections look like that.
Try "touching up" all the solder connections ... or try a section at a time. Don't over do it! You may need to add a tiny bit of new solder to get good flow. Also too much flux can cause weird problems ... particularly in high impedance circuits like LC oscillators. Take a cotton swab dipped in isopropyl alcohol (the 90% rubbing alcohol variety)and clean off all the flux around all the soldering connections. Then dry this off by patting with a dry cloth. It may take a few tries to get it all off.
You must be logged in to post a reply. Please log in or register for a new account.