OSCar - mine hums and is contaminating the other synths!

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OSCar - mine hums and is contaminating the other synths!

Post by fletriste » Wed Jan 02, 2008 12:55 pm

My OSCar doesn't like to be turned up - it has a low level hum similar to a missing ground loop on a record player - but a lot quieter....

running it through a pre-amp doesn't seem to effect the signal to hum ratio......

Any ideas? I've tried as best I can moving the OSCar around so it is away from other electrical devices (but it is rather large!)...

maybe a noise gate is the only solution but it seems a bit of a cheat.....

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Post by Solderman » Wed Jan 02, 2008 6:54 pm

I don't know if the Oscar has a headphone output, but if it does and you cannot hear hum with only the headphones(no other audio output cable attached) then it's probably just an isolation problem.

A GLI: http://www.radioshack.com/sm-more-produ ... 62214.html
plus the adapters for the sockets would be all you'd need in this case. Sometimes if it's related to ground lift on the chassis, you can use a three prong to two prong adapter on the power cable, but this is generally regarded as making the device a shock hazard under certain conditions.

If isolation isn't the problem, then most likely part of the OSCar's power supply is defective and will need repair.
Last edited by Solderman on Thu Jan 03, 2008 8:01 pm, edited 1 time in total.
I am no longer in pursuit of vintage synths. The generally absurd inflation from demand versus practical use and maintenance costs is no longer viable. The internet has suffocated and vanquished yet another wonderful hobby. Too bad.
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Post by insky » Thu Jan 03, 2008 10:48 am

Teach Oscar the words, maybe he won't hum anymore.
Stuff I own:
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Post by Altitude » Thu Jan 03, 2008 12:08 pm

hum is usually a symptom of electrolytic capacitors drying out which results in higher ripple current (hence the hum) you can get it repaired or if you want to DIY, just change all the ones on the power supply first and work your way back from there

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